Incidence of Childhood Cancer in Finland Lyly leppo,';! luula Salonen," and limo Hakulinen
1
2
The Finnish Cancer Registry was established in 1952; regular reporting began in 1953 (1) 2). The registry covers the whole country (population, ;::::;4.6 million). In 1974, a special Childhood Cancer Registry was established in connection with the Finnish Cancer Registry. Its purpose is to provide material and data for epidemiologic and clinicopathologic investigations. We now describe material from the Finnish Cancer Registry during 1953-70. MATERIALS AND METHODS
Data for all malignant tumors in children under 15 years of age reported to the Finnish Cancer Registry between 1953 and 1970 are included. "Brain tumors" also comprise benign neoplasms of the brain and the intracranial meninges. The category "lymphomas" concerned only tumors originating in the lymph nodes; if a definite primary site other than lymph nodes had been mentioned, the lymphomas were included as neoplasms of the stated organ (e.g., pharynx or intestines). Neuroblastomas have been grouped regardless of anatomic site. TABLE
Histologic confirmation of the tumor (including study of a bone-marrow or blood smear in leukemia) was obtained in 87% of cases (in 1966-70, 90%). Death certificates provided the only information in 6% of cases (in 1966-70, 3.5%). The tumor's histologic type was noted from the original reports entered at the Registry and not reclassified. The incidence rates were calculated per million and adjusted for age to the "world standard population" (3). In the analyses of incidence trends, we used the mean annual incidence rates of 6 consecutive 3-year periods from 1953-55 to 1968-70. The statistical significance of the trends was tested by linear regression and normal approximation (4). In 1953, males under 15 years of age constituted 32.5% of the total male population of Finland; the corresponding figure in 1970 was 26.0%. A similar decrease in the proportion of children also occurred among females: 28.7% in 1953,23.3% in 1970. RESULTS Leading Sites
New cancer cases in children under 15 years of age totalled 2,605 (1,440 males; 1,165 females). The mean annual age-adjusted incidence rates per million were 128 in males and 108 in females (male/female ratio, 1.2: I). The leading cancer type was leukemia, which constituted one-third of all cases in both sexes (table I). The incidence of leukemia in males (43.7) clearly exceeded that in females (34.7). One-fifth of all tumors were in the brain (table I); again, the incidence in males was higher than that in females. Received March 25, 1975; accepted July 14, 1975. Finnish Cancer Registry, Liisankatu 21 B, 00170 Helsinki 17. Finland. 3 Third Department of Pathology, University of Helsinki. 00290 Helsinki 29, Finland. 1
2
I.-Adjusted rates for leading primary sites of cancer in Finnish children under 15 years of age during 1953-70, by sex
Primary site (Males)
Number of cases
Primary site (Females)
Percent Rate/lO l
Leukemia _______________________ Brain __________________________ Lymphoma (including Hodgkin's disease). Kidney _________________________ Bone___________________________ Soft tissues _____________________ Eye ____________________________ Neuroblastoma__________________ Skin (melanoma) ________________ Other nervous system ____________ Mediastinum (including thymus) __ Skin (other) _____________________ Testis __________________________ Intestines _______________________ Pharynx ________________________ Others _________________________
486 306 129
33.8 21.3 9.0
43.7 26.4 10.8
103 67 52 50 46 19 19 17 16 16 14 13 87
7.2 4.7 3.6 3.5 3.2 1.3 1.3 1.2 1.1 1.1 1.0 0.9 6.0
10.0 5.3 4.7 4.8 4.5 1.7 1.7 1.4 1.5 1.5 1.1 1.0 7.9
TotaL _________________________
1,440
100
128.0
Number of Percent Rate/lO l cases
Leukemia ______________________ Brain __________________________ Kidney _________________________ Bone ___________________________ Lymphoma (including Hodgkin's disease). Eye____________________________ Neuroblastoma__________________ Soft tissues _____________________ Ovary__________________________ Skin (other) ____________________ Intestines ______________________ Other nervous system ____________ Skin (melanoma) ________________ Adrenal gland (excluding neuroblastomas). Thyroid gland __________________ Others _________________________
370 255 90
Total __________________________
1,165
JOURNAL OF THE NATIONAL CANCER INSTITUTE, VOL. 55, NO.5, NOVEMBER 1975
31.8 21.9 7.7 5.5 5.2
34.7 22.8 9.1 5.1 5.3
9
4.5 3.5 3.3 2.7 2.2 1.6 1.5 0.9 0.8
5.4 4.2 3.6 2.5 2.3 1.6 1.6 0.8 0.9
8 74
0.7 6.4
0.7 7.0
64
60 53 41 38 31 26 19 17 10
100
107.6
1065
Downloaded from https://academic.oup.com/jnci/article-abstract/55/5/1065/951993 by Tulane University Medical Library user on 17 January 2019
SUMMARY-Between 1953 and 1970, 2,605 malignant tumors in children under 15 years of age were reported to the Finnish Cancer Registry, a population-based registry that covers the whole country (population, 4.6 million). The mean annual ageadjusted incidence rates per million were 128 in males and 108 in females. The most common neoplasms were leukemia (age-adjusted incidence rates, 43.7 in males; 34.7 in females), brain tumors (26.4 in males, 22.8 in females), renal tumors (10.0 in males, 9.1 in females), lymphomas (10.8 in males, 5.3 in females), and bone tumors (5.3 in males, 5.1 in females). This distribution is roughly the same as that observed in many other white populations. However, the incidence rates of leukemia, lymphomas, neuroblastomas, and soft-tissue tumors were somewhat lower than the figures reported in the Third National Cancer Survey of the United States.-J Natl Cancer Inst 55: 1065-1067, 1975.
1066
TEPPO, SALONEN, AND HAKULINEN
Cell Type of Tumors
Of the leukemias, 77% (622/856) were classified as "acute". Evidently, a definite proportion of cases classified as unspecified were, in fact, acute blast leukemias. The distribution of the 189 lymphomas was: Hodgkin's disease, 87; lymphosarcoma, 50; reticulum-cell sarcoma, 20; others or unspecified, 32. The largest group within the brain tumor category was glioma (56/224, or 40%). There were 80 medulloblastomas and 56 ependymomas; neoplasms of other or unknown histologic types constituted 36%. of all brain tumors (20 cases). Of the 193 tumors of the kidney, 151 (77%) were reported as nephroblastomas: probably, many of the remaining tumors were also nephroblastomas, though the histologic type was not mentioned in the reports to the Cancer Registry. The 103 eye tumors included 79 retinoblastomas, 7 melanomas, 7 gliomas, and 10 other or unspecified tumors. Osteosarcoma comprised the largest single group of bone tumors (73/131); Ewing's sarcomas numbered 10. Tumors of the soft tissues varied greatly in histologic diagnoses, with fibrosarcoma forming the largest group (24/90). The distribution of the 16 testicular tumors was as follows: endodermal sinus tumor (yolk-sac tumor), 10; teratocarcinoma, 2; sarcoma or lymphoma, 4. Ten of the 31 tumors of the ovary were dysgerminomas; 11 were teratomas. Lymphomas constituted the largest group among tumors of the pharynx (11/18) and intestines (15/33). In addition to the 29 melanomas listed in table 1, there were 8 basal cell carcinomas, 2 epidermoid carcinomas, 8 lymphomas, and 24 sarcomas of the skin. Age-Specific Incidence Rates
The age-specific incidence of cancer of all sites displayed a peak in the fourth year of life in males and in the third year in females; the incidence declined toward puberty (text-fig. 1). In the largest single group, leukemia, the age-specific incidences exhibited a similar course: In both sexes the peak occurred during the fourth year of life (text-fig. 1). The curve for brain tumors showed a minimum incidence in the age group under 1 year; no definite peak was observable (text-fig. 1). The age-specific incidence rate of 3 embryonal tUM mors-nephroblastomas, neuroblastomas, and retinoblastomas-was highest among the youngest groups; very low figures were observed in the age group 10-14 years. Bone tumors and lymphomas, particularly Hodgkin's disease, had a different pattern: The incidence was low in small children, with a notable increase by age. The incidence of soft-tissue sarcomas was lowest at 5-9 years, and that of testicular tumors at 10-14 years. Incidence Trends
During the study period (1953-70), the increase of the total cancer incidence was statistically significant in females (P
1
2
The Finnish Cancer Registry was established in 1952; regular reporting began in 1953 (1) 2). The registry covers the whole country (population, ;::::;4.6 million). In 1974, a special Childhood Cancer Registry was established in connection with the Finnish Cancer Registry. Its purpose is to provide material and data for epidemiologic and clinicopathologic investigations. We now describe material from the Finnish Cancer Registry during 1953-70. MATERIALS AND METHODS
Data for all malignant tumors in children under 15 years of age reported to the Finnish Cancer Registry between 1953 and 1970 are included. "Brain tumors" also comprise benign neoplasms of the brain and the intracranial meninges. The category "lymphomas" concerned only tumors originating in the lymph nodes; if a definite primary site other than lymph nodes had been mentioned, the lymphomas were included as neoplasms of the stated organ (e.g., pharynx or intestines). Neuroblastomas have been grouped regardless of anatomic site. TABLE
Histologic confirmation of the tumor (including study of a bone-marrow or blood smear in leukemia) was obtained in 87% of cases (in 1966-70, 90%). Death certificates provided the only information in 6% of cases (in 1966-70, 3.5%). The tumor's histologic type was noted from the original reports entered at the Registry and not reclassified. The incidence rates were calculated per million and adjusted for age to the "world standard population" (3). In the analyses of incidence trends, we used the mean annual incidence rates of 6 consecutive 3-year periods from 1953-55 to 1968-70. The statistical significance of the trends was tested by linear regression and normal approximation (4). In 1953, males under 15 years of age constituted 32.5% of the total male population of Finland; the corresponding figure in 1970 was 26.0%. A similar decrease in the proportion of children also occurred among females: 28.7% in 1953,23.3% in 1970. RESULTS Leading Sites
New cancer cases in children under 15 years of age totalled 2,605 (1,440 males; 1,165 females). The mean annual age-adjusted incidence rates per million were 128 in males and 108 in females (male/female ratio, 1.2: I). The leading cancer type was leukemia, which constituted one-third of all cases in both sexes (table I). The incidence of leukemia in males (43.7) clearly exceeded that in females (34.7). One-fifth of all tumors were in the brain (table I); again, the incidence in males was higher than that in females. Received March 25, 1975; accepted July 14, 1975. Finnish Cancer Registry, Liisankatu 21 B, 00170 Helsinki 17. Finland. 3 Third Department of Pathology, University of Helsinki. 00290 Helsinki 29, Finland. 1
2
I.-Adjusted rates for leading primary sites of cancer in Finnish children under 15 years of age during 1953-70, by sex
Primary site (Males)
Number of cases
Primary site (Females)
Percent Rate/lO l
Leukemia _______________________ Brain __________________________ Lymphoma (including Hodgkin's disease). Kidney _________________________ Bone___________________________ Soft tissues _____________________ Eye ____________________________ Neuroblastoma__________________ Skin (melanoma) ________________ Other nervous system ____________ Mediastinum (including thymus) __ Skin (other) _____________________ Testis __________________________ Intestines _______________________ Pharynx ________________________ Others _________________________
486 306 129
33.8 21.3 9.0
43.7 26.4 10.8
103 67 52 50 46 19 19 17 16 16 14 13 87
7.2 4.7 3.6 3.5 3.2 1.3 1.3 1.2 1.1 1.1 1.0 0.9 6.0
10.0 5.3 4.7 4.8 4.5 1.7 1.7 1.4 1.5 1.5 1.1 1.0 7.9
TotaL _________________________
1,440
100
128.0
Number of Percent Rate/lO l cases
Leukemia ______________________ Brain __________________________ Kidney _________________________ Bone ___________________________ Lymphoma (including Hodgkin's disease). Eye____________________________ Neuroblastoma__________________ Soft tissues _____________________ Ovary__________________________ Skin (other) ____________________ Intestines ______________________ Other nervous system ____________ Skin (melanoma) ________________ Adrenal gland (excluding neuroblastomas). Thyroid gland __________________ Others _________________________
370 255 90
Total __________________________
1,165
JOURNAL OF THE NATIONAL CANCER INSTITUTE, VOL. 55, NO.5, NOVEMBER 1975
31.8 21.9 7.7 5.5 5.2
34.7 22.8 9.1 5.1 5.3
9
4.5 3.5 3.3 2.7 2.2 1.6 1.5 0.9 0.8
5.4 4.2 3.6 2.5 2.3 1.6 1.6 0.8 0.9
8 74
0.7 6.4
0.7 7.0
64
60 53 41 38 31 26 19 17 10
100
107.6
1065
Downloaded from https://academic.oup.com/jnci/article-abstract/55/5/1065/951993 by Tulane University Medical Library user on 17 January 2019
SUMMARY-Between 1953 and 1970, 2,605 malignant tumors in children under 15 years of age were reported to the Finnish Cancer Registry, a population-based registry that covers the whole country (population, 4.6 million). The mean annual ageadjusted incidence rates per million were 128 in males and 108 in females. The most common neoplasms were leukemia (age-adjusted incidence rates, 43.7 in males; 34.7 in females), brain tumors (26.4 in males, 22.8 in females), renal tumors (10.0 in males, 9.1 in females), lymphomas (10.8 in males, 5.3 in females), and bone tumors (5.3 in males, 5.1 in females). This distribution is roughly the same as that observed in many other white populations. However, the incidence rates of leukemia, lymphomas, neuroblastomas, and soft-tissue tumors were somewhat lower than the figures reported in the Third National Cancer Survey of the United States.-J Natl Cancer Inst 55: 1065-1067, 1975.
1066
TEPPO, SALONEN, AND HAKULINEN
Cell Type of Tumors
Of the leukemias, 77% (622/856) were classified as "acute". Evidently, a definite proportion of cases classified as unspecified were, in fact, acute blast leukemias. The distribution of the 189 lymphomas was: Hodgkin's disease, 87; lymphosarcoma, 50; reticulum-cell sarcoma, 20; others or unspecified, 32. The largest group within the brain tumor category was glioma (56/224, or 40%). There were 80 medulloblastomas and 56 ependymomas; neoplasms of other or unknown histologic types constituted 36%. of all brain tumors (20 cases). Of the 193 tumors of the kidney, 151 (77%) were reported as nephroblastomas: probably, many of the remaining tumors were also nephroblastomas, though the histologic type was not mentioned in the reports to the Cancer Registry. The 103 eye tumors included 79 retinoblastomas, 7 melanomas, 7 gliomas, and 10 other or unspecified tumors. Osteosarcoma comprised the largest single group of bone tumors (73/131); Ewing's sarcomas numbered 10. Tumors of the soft tissues varied greatly in histologic diagnoses, with fibrosarcoma forming the largest group (24/90). The distribution of the 16 testicular tumors was as follows: endodermal sinus tumor (yolk-sac tumor), 10; teratocarcinoma, 2; sarcoma or lymphoma, 4. Ten of the 31 tumors of the ovary were dysgerminomas; 11 were teratomas. Lymphomas constituted the largest group among tumors of the pharynx (11/18) and intestines (15/33). In addition to the 29 melanomas listed in table 1, there were 8 basal cell carcinomas, 2 epidermoid carcinomas, 8 lymphomas, and 24 sarcomas of the skin. Age-Specific Incidence Rates
The age-specific incidence of cancer of all sites displayed a peak in the fourth year of life in males and in the third year in females; the incidence declined toward puberty (text-fig. 1). In the largest single group, leukemia, the age-specific incidences exhibited a similar course: In both sexes the peak occurred during the fourth year of life (text-fig. 1). The curve for brain tumors showed a minimum incidence in the age group under 1 year; no definite peak was observable (text-fig. 1). The age-specific incidence rate of 3 embryonal tUM mors-nephroblastomas, neuroblastomas, and retinoblastomas-was highest among the youngest groups; very low figures were observed in the age group 10-14 years. Bone tumors and lymphomas, particularly Hodgkin's disease, had a different pattern: The incidence was low in small children, with a notable increase by age. The incidence of soft-tissue sarcomas was lowest at 5-9 years, and that of testicular tumors at 10-14 years. Incidence Trends
During the study period (1953-70), the increase of the total cancer incidence was statistically significant in females (P
