Journal of Genetic Counseling, Vol. 6, No. 2, 1997
Knowledge of Breast Cancer Genetics Among Breast Cancer Patients and First-Degree Relatives of Affected Individuals Aimee L. Wonderlick1,2 and Beth A. Fine1
The cloning of BRCA1, a susceptibility gene for inherited breast cancer, has made genetic screening possible for individuals and families whose medical histories are suggestive of an inherited predisposition to breast cancer. To date, few systematic attempts have been made to determine the level of knowledge about breast cancer genetics among women who are likely to seek BRCA1 screening when it becomes widely available. The present study attempted to assess the general knowledge about BRCA1 mutations in two groups: (1) first-degree relatives (FDRs) of breast cancer patients; and (2) women with a previous diagnosis of breast cancer. A self-administered, thirty-item questionnaire was developed through a pilot study. Ten of the items were objective, factual questions about breast cancer genetics. Responses to these questions were used to generate an overall knowledge score for each respondent. The study population was moderately knowledgeable about breast cancer genetics, with an average score of 5.35 out of 10. Counselors should not underestimate the importance of evaluating each counselee's existing knowledge about breast cancer, which can affect the provision and reception of genetic information. In particular, specific areas of knowledge that may be confusing or misunderstood were identified and these topics are discussed in detail. KEY WORDS: breast cancer; BRCA1; knowledge; susceptibility testing; genetic counseling.
1
Section of Reproductive Genetics, Department of Obstetrics and Gynecology, Northwestern University Medical School, Chicago, Illinois. Correspondence should be directed to Aimee Wonderlick, Section of Reproductive Genetics, Prentice Women's Hospital, 333 East Superior St. Suite 1543, Chicago, Illinois 60611.
2
111 1059-7700/97/0600-Om$12.50/l C 1997 National Society of Genetic Counselors, Inc.
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Wonderlick and Fine
INTRODUCTION The cloning of BRCA1, a susceptibility gene for inherited breast cancer, has made genetic screening possible for individuals and families whose medical histories are suggestive of an inherited predisposition to breast cancer. Several issues must be addressed before BRCA1 testing becomes widely available, including the risks of developing cancer associated with specific mutations, the effectiveness of monitoring and preventive strategies in mutation carriers, the assurance of quality control among laboratories performing BRCA1 testing, the possibility of discrimination based on genetic testing results, and determination of the optimal approach to educating the public and professionals about the complexities of genetic testing for cancer risk (Collins, 1996; National Advisory Council for Human Genome Research, 1994; American Society of Human Genetics Ad Hoc Committee on Breast and Ovarian Cancer Screening, 1994). As progress is made in addressing these issues, genetic testing for breast cancer susceptibility is likely to become an increasingly important component of medical evaluation for certain individuals. Female BRCA1 mutation carriers have an 80-90% lifetime risk of breast cancer and a significantly increased lifetime risk of ovarian cancer (Easton et al., 1993; Ford et al 1994). Additionally, BRCA1 mutation carriers have a relative risk (RR) >4 for colon cancer and >3 for prostate cancer (males) (Ford et al., 1994). The general population incidence of BRCA1 mutation carriers is estimated to be between 1 in 500 and 1 in 2000 (Easton et al, 1994). It is estimated that 5% of all breast cancers and approximately 25% of breast cancer cases diagnosed before age 30 are due to inherited genetic mutations (Claus et al,, 1991). To date, few systematic attempts have been made to determine the level of knowledge about breast cancer genetics among women who are likely to seek genetic screening. Research in this area is critical to the development of counseling protocols for BRCA1 testing. Furthermore, an assessment of an individual's prior knowledge and beliefs about breast cancer contributes to effective genetic counseling, while permitting the counselor to address and clarify any misconceptions (Hoskins et al., 1995; Richards et al., 1995). Genetic counseling for breast cancer may be inherently different from that for most Mendelian disorders. For example, the majority of breast cancer cases are not due to an inherited gene mutation (Lerman, 1994). Therefore, a critical component of obtaining informed consent will be ensuring that counselees understand the limitations of BRCA1 screening (Lerman, 1994; Peshkin, 1996). Finally, while many genetic tests are performed almost exclusively to learn about the risk of disease in future generations,
Knowledge of Breast Cancer Genetics Among Patients and First-Degree Relatives
113
women seeking BRCA1 screening will obtain results that directly affect their own health. For these reasons, a careful consideration of the approach to, and manner of, delivering information will be required to develop optimal strategies for breast cancer genetic counseling (Rowell et al., 1994). A more complete understanding of the precounseling knowledge about cancer genetics among women who are possible candidates for BRCA1 screening will facilitate developing counseling protocols and creating educational materials for participants. Studies concerning the anticipated interest in genetic testing for breast cancer susceptibility have found that 87-96% of women surveyed indicated that they would undergo such testing (Lerman et al., 1994, 1995; Struewing et al, 1995; Chaliki et al., 1995; Beeman et al., 1995). These studies provided a standardized statement about the availability of genetic screening for breast cancer susceptibility and then assessed participants' attitudes about being tested. However, these studies did not assess how well the participants actually understood the facts of inherited breast cancer. Recent information obtained from women voluntarily attending focus groups about BRCA1 screening found, "that when women are given information about the test itself, and not merely about its availability, their interest in testing wanes" (Geller et al., 1995). The present study attempted to assess the general knowledge of BRCA1 mutations in two groups: (1) first-degree relatives (FDRs) of breast cancer patients; and (2) women with a previous diagnosis of breast cancer. FDRs may be more likely to seek genetic screening for breast cancer than women without a family history of breast cancer. Breast cancer patients may seek such testing in order to help other relatives determine their risks of breast cancer. These two populations are likely to be the first to come forward when BRCA1 screening is widely available.
MATERIALS AND METHODS Questionnaire A self-administered questionnaire was developed through a pilot study based on individual interviews conducted with six female breast cancer patients (two African-American, two Caucasian, and two Hispanic) identified through Northwestern Memorial Hospital's Radiation Oncology department. The women were asked about their estimate of the general population risk for breast cancer, their two main sources of information about breast cancer, their understanding about the causes of breast cancer, and their beliefs about the role of heredity in the development of breast cancer.
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The women responded in an open-ended manner. All interviews were taperecorded and later transcribed. Responses from the interviews indicated that the women had different ideas about the causes of breast cancer. Overall, the women knew little about the specifics of breast cancer genes and none mentioned the term "BRCA1." However, all women seemed to be comfortable with the word "gene" and understood it to be related to heredity. The questionnaire, developed based on the interviews described above, consisted of 30 items (Appendix). The first two items addressed women's sources of knowledge about breast cancer and their perception of the population risk for breast cancer. The second section of the questionnaire, the "genetics" section, consisted of thirteen items concerning the relationship between breast cancer and genetics. Short descriptions of genes and gene mutations were provided in a preamble to the questions. Ten questions in the "genetics" section were objective, factual questions about breast cancer genetics. Responses to these questions were used to generate an overall knowledge score for each respondent. The last section consisted of questions concerning each respondent, including family history of breast cancer, frequency of breast self-examination and mammography, and demographic data. Study Population The study was approved by the Institutional Review Board at Northwestern University. The final sample consisted of 47 unaffected women with a family history of breast cancer in at least one first-degree relative (FDR) and 27 women who had a prior diagnosis of breast cancer. The FDRs were derived from women who were previously identified through Northwestern Memorial Hospital's participation in the National Surgical Adjuvant Breast and Bowel Project (N.S.A.B.P). In 1993, these women attended an informational meeting about the N.S.A.B.P Breast Cancer Prevention Trial that was advertised in the local media. The presentation at this meeting did not include information about breast cancer genetics. The women identified for the present study consisted both of women participating in the N.S.A.B.P. trial and those that were ineligible. A questionnaire was mailed to the 157 women along with a cover letter explaining that the questionnaire concerned "women's thoughts about the causes of breast cancer and their knowledge about specific breast cancer issues" and required approximately 15 minutes to complete. The cover letter also explained that some items on the questionnaire concerned genetics and that participants were not expected to know the correct answer to each
Knowledge of Breast Cancer Genetics Among Patients and First-Degree Relatives
115
question. A pre-addressed stamped envelope was included in the mailing and the name and phone number of the investigator (ALW) was provided. Respondents were asked to return the survey within 1 month. Women previously diagnosed with breast cancer were identified through the Northwestern Medical Faculty Foundation Section of Hematology/Oncology, the Radiation Oncology Department, and the Lynn Sage Breast Center at Northwestern Memorial Hospital. Prospective participants were approached either immediately before or after they were examined by their physician. Patients who were undergoing daily radiation treatment for breast cancer were approached in the waiting room before their treatment. Prospective participants were provided a questionnaire and cover letter and given a brief verbal description of the study. The cover letter contained the same information as the letter received by the FDRs. A preaddressed, stamped envelope was provided and the women were asked to return the questionnaire as soon as possible. Questionnaires were mailed to 157 potential FDRs. Fifteen questionnaires were returned by the post office as undeliverable. Of the remaining 142 questionnaires, 67 were returned, giving a response rate of 47%. However, 20 of the returned questionnaires were completed by women who reported no first-degree relatives with breast cancer, and their responses were excluded from analysis. Therefore, the sample of FDRs consisted of 47 completed questionnaires. Questionnaires were distributed to 43 women with a previous diagnosis of breast cancer (hereafter referred to as "patients"). Twenty-seven completed questionnaires were returned, giving a response rate of 63%.
RESULTS Characteristics of the Study Population The majority of respondents were Caucasian (94%) and employed (77%). Only four of 74 respondents were non-Caucasian (two AfricanAmerican, one Asian, and one Hispanic). All non-Caucasian respondents were breast cancer patients, and thus all FDRs were Caucasian. The respondents were generally well-educated, with approximately 70% having, at minimum, a Bachelor's degree. Sixty-two percent of the women had children. There were no significant differences between the two groups for the variables of marital status, employment, college education, or having children. Among FDRs, 81% reported having one FDR with breast cancer, 13% reported having two affected FDRs, and 6% reported having three affected
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FDRs. Among breast cancer patients, 89% reported no history of breast cancer in a FDR, while 11% (n=3) reported at least one affected FDR. The majority (92.5%) of patients had been diagnosed with breast cancer within the last 5 years, and a large proportion had been diagnosed within the last year (44%). The number of years since diagnosis ranged from 1 to 12. Ninety-six percent of patients had unilateral breast cancer and 70% were currently undergoing breast cancer treatment. Fifty-nine percent of breast cancer patients were under the age of 50 (range: 32-73). General Breast Cancer Information The majority of FDRs and patients indicated that physicians were one of their two most important sources of information. FDRs were more likely to obtain information from newspapers and friends or relatives, while patients were much more likely to consult books. FDRs and patients were similar in their estimation of the general population lifetime risk of breast cancer. The mean for FDRs was 1 in 14 and the mean for patients was 1 in 13.5. The latest estimate of the lifetime probability for breast cancer in American women, using age 95 as a cut-off, is 1 in 8 (Parker et al., 1996). Although the means for both groups underestimated a woman's lifetime risk of breast cancer, approximately 60% of respondents in both groups provided an answer of 1 in 8, 9, or 10, all very close to the correct figure. There were no significant differences in estimates of the general population risk between women with and without a family history of breast cancer, between women with and without a college education, or between breast cancer patients under the age of 50 and age 50 and above. When asked about environmental and genetic contributions to the cause of breast cancer, 48% and 58.7% of patients and FDRs, respectively, responded that both were important. For patients, the second most frequent response was that environmental factors were more important in the development of breast cancer (28%), while the second most frequent response among FDRs was genes (26.1%). Although women at increased risk for breast cancer were more likely than women who have had breast cancer to choose genetic factors as causative in the development of the disease; the difference was not statistically significant. Breast Cancer Genetics The majority of respondents had heard of a gene mutation that causes a woman to have a higher chance of developing breast cancer. Eighty-three percent of FDRs and 63% of patients responded "yes" when asked this
Knowledge of Breast Cancer Genetics Among Patients and First-Degree Relatives
117
question (p = 0.05; chi-square). When specifically asked if they had ever heard of a gene called BRCA1, 36.2% of FDRs and 38.5% of patients responded, "yes." Overall Knowledge Score An overall knowledge score was computed for each respondent by summing the number of correct responses to the ten items in Tables I and II. Questions in Table I were categorical, i.e., respondents were provided choices and asked to mark their answer. Questions in Table II were continuous, i.e., respondents answered as a percentage. For the question, "What percentage of all breast cancer cases are caused by a gene mutation?" responses of 10% or less were counted as correct, as up to 10% of cases may be attributable to an inherited gene mutation if other genes are considered in addition to BRCA1 (Hoskins et al, 1995). Tables I and II summarize the responses of FDRs and patients to the ten questions comprising the knowledge score. Figure 1 stratifies respondents by score. The average overall knowledge score among all respondents was 5.35 out of 10 (SD = 1.88), with a range of 0-9. There were no significant differences in the average scores between FDRs and patients, between married and unmarried women, between women with and without a college education, between women who were employed and unemployed, between patients who were currently undergoing treatment and those that were not, between patients under the age of 50 and those age 50 and above, or between women who had a FDR with breast cancer and those who did not. The most significant differences in average scores were between women who had heard of a gene mutation associated with breast cancer and those who had not (5.6 vs. 4.4, p = 0.02; two-tailed t-test), and between women who had heard of BRCA1 and those who had not (6.2 vs. 4.9, p = 0.003; two-tailed t-test). Respondents generally overestimated the percentage of breast cancer cases that are caused by an inherited susceptibility gene such as BRCA1. The average of all responses to the question, "What percentage of all breast cancer cases are caused by a gene mutation?" was 39.2% (SD = 22.9). There were no significant differences in the average of responses between women with and without a family history of breast cancer, between women with and without a college education, or between breast cancer patients under the age of 50 and age 50 and above. Table II shows the percentage of responses to this question that fell into three categories, less than or equal to 10% (considered the "correct" response), 11-50%, and 51-100%.
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Knowledge of Breast Cancer Genetics Among Patients and First-Degree Relatives
119
Table II. Responses to Continuous Knowledge Questions"
What percentage of all breast cancer cases are caused by a gene mutation?
FDRs Patients
50%
Knowledge of Breast Cancer Genetics Among Breast Cancer Patients and First-Degree Relatives of Affected Individuals Aimee L. Wonderlick1,2 and Beth A. Fine1
The cloning of BRCA1, a susceptibility gene for inherited breast cancer, has made genetic screening possible for individuals and families whose medical histories are suggestive of an inherited predisposition to breast cancer. To date, few systematic attempts have been made to determine the level of knowledge about breast cancer genetics among women who are likely to seek BRCA1 screening when it becomes widely available. The present study attempted to assess the general knowledge about BRCA1 mutations in two groups: (1) first-degree relatives (FDRs) of breast cancer patients; and (2) women with a previous diagnosis of breast cancer. A self-administered, thirty-item questionnaire was developed through a pilot study. Ten of the items were objective, factual questions about breast cancer genetics. Responses to these questions were used to generate an overall knowledge score for each respondent. The study population was moderately knowledgeable about breast cancer genetics, with an average score of 5.35 out of 10. Counselors should not underestimate the importance of evaluating each counselee's existing knowledge about breast cancer, which can affect the provision and reception of genetic information. In particular, specific areas of knowledge that may be confusing or misunderstood were identified and these topics are discussed in detail. KEY WORDS: breast cancer; BRCA1; knowledge; susceptibility testing; genetic counseling.
1
Section of Reproductive Genetics, Department of Obstetrics and Gynecology, Northwestern University Medical School, Chicago, Illinois. Correspondence should be directed to Aimee Wonderlick, Section of Reproductive Genetics, Prentice Women's Hospital, 333 East Superior St. Suite 1543, Chicago, Illinois 60611.
2
111 1059-7700/97/0600-Om$12.50/l C 1997 National Society of Genetic Counselors, Inc.
112
Wonderlick and Fine
INTRODUCTION The cloning of BRCA1, a susceptibility gene for inherited breast cancer, has made genetic screening possible for individuals and families whose medical histories are suggestive of an inherited predisposition to breast cancer. Several issues must be addressed before BRCA1 testing becomes widely available, including the risks of developing cancer associated with specific mutations, the effectiveness of monitoring and preventive strategies in mutation carriers, the assurance of quality control among laboratories performing BRCA1 testing, the possibility of discrimination based on genetic testing results, and determination of the optimal approach to educating the public and professionals about the complexities of genetic testing for cancer risk (Collins, 1996; National Advisory Council for Human Genome Research, 1994; American Society of Human Genetics Ad Hoc Committee on Breast and Ovarian Cancer Screening, 1994). As progress is made in addressing these issues, genetic testing for breast cancer susceptibility is likely to become an increasingly important component of medical evaluation for certain individuals. Female BRCA1 mutation carriers have an 80-90% lifetime risk of breast cancer and a significantly increased lifetime risk of ovarian cancer (Easton et al., 1993; Ford et al 1994). Additionally, BRCA1 mutation carriers have a relative risk (RR) >4 for colon cancer and >3 for prostate cancer (males) (Ford et al., 1994). The general population incidence of BRCA1 mutation carriers is estimated to be between 1 in 500 and 1 in 2000 (Easton et al, 1994). It is estimated that 5% of all breast cancers and approximately 25% of breast cancer cases diagnosed before age 30 are due to inherited genetic mutations (Claus et al,, 1991). To date, few systematic attempts have been made to determine the level of knowledge about breast cancer genetics among women who are likely to seek genetic screening. Research in this area is critical to the development of counseling protocols for BRCA1 testing. Furthermore, an assessment of an individual's prior knowledge and beliefs about breast cancer contributes to effective genetic counseling, while permitting the counselor to address and clarify any misconceptions (Hoskins et al., 1995; Richards et al., 1995). Genetic counseling for breast cancer may be inherently different from that for most Mendelian disorders. For example, the majority of breast cancer cases are not due to an inherited gene mutation (Lerman, 1994). Therefore, a critical component of obtaining informed consent will be ensuring that counselees understand the limitations of BRCA1 screening (Lerman, 1994; Peshkin, 1996). Finally, while many genetic tests are performed almost exclusively to learn about the risk of disease in future generations,
Knowledge of Breast Cancer Genetics Among Patients and First-Degree Relatives
113
women seeking BRCA1 screening will obtain results that directly affect their own health. For these reasons, a careful consideration of the approach to, and manner of, delivering information will be required to develop optimal strategies for breast cancer genetic counseling (Rowell et al., 1994). A more complete understanding of the precounseling knowledge about cancer genetics among women who are possible candidates for BRCA1 screening will facilitate developing counseling protocols and creating educational materials for participants. Studies concerning the anticipated interest in genetic testing for breast cancer susceptibility have found that 87-96% of women surveyed indicated that they would undergo such testing (Lerman et al., 1994, 1995; Struewing et al, 1995; Chaliki et al., 1995; Beeman et al., 1995). These studies provided a standardized statement about the availability of genetic screening for breast cancer susceptibility and then assessed participants' attitudes about being tested. However, these studies did not assess how well the participants actually understood the facts of inherited breast cancer. Recent information obtained from women voluntarily attending focus groups about BRCA1 screening found, "that when women are given information about the test itself, and not merely about its availability, their interest in testing wanes" (Geller et al., 1995). The present study attempted to assess the general knowledge of BRCA1 mutations in two groups: (1) first-degree relatives (FDRs) of breast cancer patients; and (2) women with a previous diagnosis of breast cancer. FDRs may be more likely to seek genetic screening for breast cancer than women without a family history of breast cancer. Breast cancer patients may seek such testing in order to help other relatives determine their risks of breast cancer. These two populations are likely to be the first to come forward when BRCA1 screening is widely available.
MATERIALS AND METHODS Questionnaire A self-administered questionnaire was developed through a pilot study based on individual interviews conducted with six female breast cancer patients (two African-American, two Caucasian, and two Hispanic) identified through Northwestern Memorial Hospital's Radiation Oncology department. The women were asked about their estimate of the general population risk for breast cancer, their two main sources of information about breast cancer, their understanding about the causes of breast cancer, and their beliefs about the role of heredity in the development of breast cancer.
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Wonderlick and Fine
The women responded in an open-ended manner. All interviews were taperecorded and later transcribed. Responses from the interviews indicated that the women had different ideas about the causes of breast cancer. Overall, the women knew little about the specifics of breast cancer genes and none mentioned the term "BRCA1." However, all women seemed to be comfortable with the word "gene" and understood it to be related to heredity. The questionnaire, developed based on the interviews described above, consisted of 30 items (Appendix). The first two items addressed women's sources of knowledge about breast cancer and their perception of the population risk for breast cancer. The second section of the questionnaire, the "genetics" section, consisted of thirteen items concerning the relationship between breast cancer and genetics. Short descriptions of genes and gene mutations were provided in a preamble to the questions. Ten questions in the "genetics" section were objective, factual questions about breast cancer genetics. Responses to these questions were used to generate an overall knowledge score for each respondent. The last section consisted of questions concerning each respondent, including family history of breast cancer, frequency of breast self-examination and mammography, and demographic data. Study Population The study was approved by the Institutional Review Board at Northwestern University. The final sample consisted of 47 unaffected women with a family history of breast cancer in at least one first-degree relative (FDR) and 27 women who had a prior diagnosis of breast cancer. The FDRs were derived from women who were previously identified through Northwestern Memorial Hospital's participation in the National Surgical Adjuvant Breast and Bowel Project (N.S.A.B.P). In 1993, these women attended an informational meeting about the N.S.A.B.P Breast Cancer Prevention Trial that was advertised in the local media. The presentation at this meeting did not include information about breast cancer genetics. The women identified for the present study consisted both of women participating in the N.S.A.B.P. trial and those that were ineligible. A questionnaire was mailed to the 157 women along with a cover letter explaining that the questionnaire concerned "women's thoughts about the causes of breast cancer and their knowledge about specific breast cancer issues" and required approximately 15 minutes to complete. The cover letter also explained that some items on the questionnaire concerned genetics and that participants were not expected to know the correct answer to each
Knowledge of Breast Cancer Genetics Among Patients and First-Degree Relatives
115
question. A pre-addressed stamped envelope was included in the mailing and the name and phone number of the investigator (ALW) was provided. Respondents were asked to return the survey within 1 month. Women previously diagnosed with breast cancer were identified through the Northwestern Medical Faculty Foundation Section of Hematology/Oncology, the Radiation Oncology Department, and the Lynn Sage Breast Center at Northwestern Memorial Hospital. Prospective participants were approached either immediately before or after they were examined by their physician. Patients who were undergoing daily radiation treatment for breast cancer were approached in the waiting room before their treatment. Prospective participants were provided a questionnaire and cover letter and given a brief verbal description of the study. The cover letter contained the same information as the letter received by the FDRs. A preaddressed, stamped envelope was provided and the women were asked to return the questionnaire as soon as possible. Questionnaires were mailed to 157 potential FDRs. Fifteen questionnaires were returned by the post office as undeliverable. Of the remaining 142 questionnaires, 67 were returned, giving a response rate of 47%. However, 20 of the returned questionnaires were completed by women who reported no first-degree relatives with breast cancer, and their responses were excluded from analysis. Therefore, the sample of FDRs consisted of 47 completed questionnaires. Questionnaires were distributed to 43 women with a previous diagnosis of breast cancer (hereafter referred to as "patients"). Twenty-seven completed questionnaires were returned, giving a response rate of 63%.
RESULTS Characteristics of the Study Population The majority of respondents were Caucasian (94%) and employed (77%). Only four of 74 respondents were non-Caucasian (two AfricanAmerican, one Asian, and one Hispanic). All non-Caucasian respondents were breast cancer patients, and thus all FDRs were Caucasian. The respondents were generally well-educated, with approximately 70% having, at minimum, a Bachelor's degree. Sixty-two percent of the women had children. There were no significant differences between the two groups for the variables of marital status, employment, college education, or having children. Among FDRs, 81% reported having one FDR with breast cancer, 13% reported having two affected FDRs, and 6% reported having three affected
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FDRs. Among breast cancer patients, 89% reported no history of breast cancer in a FDR, while 11% (n=3) reported at least one affected FDR. The majority (92.5%) of patients had been diagnosed with breast cancer within the last 5 years, and a large proportion had been diagnosed within the last year (44%). The number of years since diagnosis ranged from 1 to 12. Ninety-six percent of patients had unilateral breast cancer and 70% were currently undergoing breast cancer treatment. Fifty-nine percent of breast cancer patients were under the age of 50 (range: 32-73). General Breast Cancer Information The majority of FDRs and patients indicated that physicians were one of their two most important sources of information. FDRs were more likely to obtain information from newspapers and friends or relatives, while patients were much more likely to consult books. FDRs and patients were similar in their estimation of the general population lifetime risk of breast cancer. The mean for FDRs was 1 in 14 and the mean for patients was 1 in 13.5. The latest estimate of the lifetime probability for breast cancer in American women, using age 95 as a cut-off, is 1 in 8 (Parker et al., 1996). Although the means for both groups underestimated a woman's lifetime risk of breast cancer, approximately 60% of respondents in both groups provided an answer of 1 in 8, 9, or 10, all very close to the correct figure. There were no significant differences in estimates of the general population risk between women with and without a family history of breast cancer, between women with and without a college education, or between breast cancer patients under the age of 50 and age 50 and above. When asked about environmental and genetic contributions to the cause of breast cancer, 48% and 58.7% of patients and FDRs, respectively, responded that both were important. For patients, the second most frequent response was that environmental factors were more important in the development of breast cancer (28%), while the second most frequent response among FDRs was genes (26.1%). Although women at increased risk for breast cancer were more likely than women who have had breast cancer to choose genetic factors as causative in the development of the disease; the difference was not statistically significant. Breast Cancer Genetics The majority of respondents had heard of a gene mutation that causes a woman to have a higher chance of developing breast cancer. Eighty-three percent of FDRs and 63% of patients responded "yes" when asked this
Knowledge of Breast Cancer Genetics Among Patients and First-Degree Relatives
117
question (p = 0.05; chi-square). When specifically asked if they had ever heard of a gene called BRCA1, 36.2% of FDRs and 38.5% of patients responded, "yes." Overall Knowledge Score An overall knowledge score was computed for each respondent by summing the number of correct responses to the ten items in Tables I and II. Questions in Table I were categorical, i.e., respondents were provided choices and asked to mark their answer. Questions in Table II were continuous, i.e., respondents answered as a percentage. For the question, "What percentage of all breast cancer cases are caused by a gene mutation?" responses of 10% or less were counted as correct, as up to 10% of cases may be attributable to an inherited gene mutation if other genes are considered in addition to BRCA1 (Hoskins et al, 1995). Tables I and II summarize the responses of FDRs and patients to the ten questions comprising the knowledge score. Figure 1 stratifies respondents by score. The average overall knowledge score among all respondents was 5.35 out of 10 (SD = 1.88), with a range of 0-9. There were no significant differences in the average scores between FDRs and patients, between married and unmarried women, between women with and without a college education, between women who were employed and unemployed, between patients who were currently undergoing treatment and those that were not, between patients under the age of 50 and those age 50 and above, or between women who had a FDR with breast cancer and those who did not. The most significant differences in average scores were between women who had heard of a gene mutation associated with breast cancer and those who had not (5.6 vs. 4.4, p = 0.02; two-tailed t-test), and between women who had heard of BRCA1 and those who had not (6.2 vs. 4.9, p = 0.003; two-tailed t-test). Respondents generally overestimated the percentage of breast cancer cases that are caused by an inherited susceptibility gene such as BRCA1. The average of all responses to the question, "What percentage of all breast cancer cases are caused by a gene mutation?" was 39.2% (SD = 22.9). There were no significant differences in the average of responses between women with and without a family history of breast cancer, between women with and without a college education, or between breast cancer patients under the age of 50 and age 50 and above. Table II shows the percentage of responses to this question that fell into three categories, less than or equal to 10% (considered the "correct" response), 11-50%, and 51-100%.
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Wonderlick and Fine
Knowledge of Breast Cancer Genetics Among Patients and First-Degree Relatives
119
Table II. Responses to Continuous Knowledge Questions"
What percentage of all breast cancer cases are caused by a gene mutation?
FDRs Patients
50%
