The Journal of International Medical Research 1990; 18(suppl 1): 3 - 7

Epidemiology of Prostatic Cancer B. Debre, M. Geraud, T. Flam and A. Steg Urological Service, Hopital Cochin, 75674 Paris, France

The worldwide incidence of prostatic cancer derived from data published by the Union Internationale contre Ie Cancer and the International Red Cross Committee has been estimated to be 200 000 new cases each year. Cases occur predominantly in the USA (75 per 100 000) and in northern Europe (40 per 100 000), whereas the incidence is low in Asia. Comparison of clinical series and autopsies confirms the high incidence of cancer in older age groups, although not all cases are seen clinically. Mortality increases more slowly than the incidence of the disease, indicating that diagnosis and treatment are increasingly effective. Aetiological factors remain the subject of much discussion, without any criteria appearing to be dominant. L'incidence du cancer prostatique dans Ie monde, selon les publications de I'Union Internationale contre Ie Cancer et Ie Comite International de la Croix-Rouge (International Red Cross Committee) a ete estimee a200 000 nouveaux cas par an avec une predominance aux EtatsUnis (75 par 100 000) et en Europe du nord (40 par 100000), les pays asiatiques se voyant epargnes. La comparaison de series cliniques et d'autopsies confirme la haute incidence de ce cancer chez les personnes plus agees, bien que tous les cas n'aient pas ete verifies en pratique c1inique.La mortallte croit moins vite que I'incidence de la maladie, ce qui traduit une meilleure performance du diagnostic et du traitement. Les donnees etiologiques restent tres controversees sans critere dominant. L'incidenza del cancro prostatico su scala mondiale, sulla base dei dati pubblicati dalla Union Internationale contre Ie Cancer e dal Comitato della Croce Rossa Internazionale, estata stimata in circa 200.000nuovi casi all'anno. La maggiore incidenza di casi si riscontra negli USA (75 su 100.000) e nell'Europa Settentrionale (40 su 100.000), mentre si registra un'incidenza minore in Asia. Il confronto delle cartelle cliniche e dei risultati delle autopsie conferma I'elevata incidenza del Address for correspondence: Professor B. Debre, Service d'Urologie, Hopital Cochin, 27 Rue du Faubourg Saint Jacques, 75674 Paris Cedex 14, France. © Copyright 1990 by Cambridge Medica! Publications Ltd

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B. Debre, M. Geraud, T. Flam et al.

cancro nei gruppi di soggetti di eta pin avanzata, sebbene non tutti i casi siano stati considerati clinicamente. II tasso di mortalita registra un incremento pin lento rispetto all'incidenza della malattia, it che indica che Iemetodologie diagnostiche e terapeutiche divengono sempre pin efficaci. I fattori eziologici rimangono I'oggetto di notevoli discussioni, senza che sia stato ancora individuato aleun criterio predominante. KEY WORDS: Prostatic cancer; epidemiology.

INTRODUCTION

denocarcinoma of the prostate is rare before the age of 50 years but thereafter it occurs at an increasing rate with age, reaching peak incidence during the eighth decade. The disease occurs in many forms and includes tumours with widely different activities. Its incidence and repercussions are not easily discernible from the statistical data.

A

INCIDENCE

Incidence is an expression of the number of new cases of the cancer occurring per year per 100 000 inhabitants. Data are published in volumes I - IV of Cancer Incidence in Five Continents, produced by the Union Internationale contre Ie Cancer and the International Red Cross Committee! for a period covering on average the years 1958 - 1977 for all countries. The incidence for France has been derived from the registers for the departments Bas Rhin, Doubs and Isere.' - 5 Based on those data, it has been estimated that approximately 200 000 new cases ofclinicalprostatic cancer occurred worldwide in 1975, thus making this the fifth most common cancer in men in the world and the second most common in industrialized countries. Incidence was highest in the USA (75 per 100000),6 the tumour being particularly prevalent in the Black populations with Alameda County, California having an exceptionally high incidence of 100.2 per 100 000. The incidence among Caucasians in the same region was about 40 - 60

per 100000. A similarly high incidence has been observed in Australia and in northern Europe, especially Scandinavia. In general, the incidence in Europe is in the region of 10 - 40 per 100 000, e.g. France 23 per 100000, FRO 28.7 per 100 000. Incidence was lowest in Asian countries, e.g. India 6.2 - 6.8 per 100000, Japan 3.1 per 100 000 and Shanghai, People's Republic of China only 0.8 per 100 000. When considering the incidence in Africa, there is a striking contrast between the relatively low incidence of 4.3 per 100 000 in Senegal and the high incidence of 32.4 per 100 000 found in the Black population of Bulawayo. This may be explained by the fact that an especially high percentage of autopsies were performed in Bulawayo during the period when the survey was carried out.' PREVALENCE

Prevalence denotes the .total number of cases of a disease in existence at a certain time in a designated area. The actual prevalence of prostatic cancer is not known but it can be considered to be widely prevalent if it is assumed that between 5% and 40% of patients over 50 years have carcinoma of the prostate - confirmed on adenomectomy or at autopsy - then prostatic cancer might actually be the most frequent cancer encountered; in France, for example it represents 18% of all cases of male cancer. In particular, the prevalence of prostatic cancer has been studied in two important investigations: one involved results from autopsy, and the other was based on clinical

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Epidemiology of prostatic cancer results. In a series of autopsies performed on patients over 50 years of age who had died from causes other than prostatic cancer, Franks" discovered that the prevalence of adenocarcinoma of the prostate was 30% between 50 and 59 years, 40% between 70 and 79 years and 67% between 80 and 89 years. Scheldon et al? established the prevalence of prostatic cancer in patients who had undergone transurethral resection was 6.4% in patients between 50 and 59 years, 18.5% in those between 60 and 69 years, and 28.7% in those between 70 and 79 years. It has been estimated that 90% of cases of prostatic cancer that occur in men over 70 years of age are not diagnosed. MORTALITY

Data for mortality due to prostatic cancer have the advantage that they do not tend to be distorted by latent carcinoma which does not generally appear on death certificates.'? Mortality statistics, therefore, seem to be more reliable than data concerning incidence but the underlying cause of death reported in death certificates may in fact be much more debatable as far as the older age groups are concerned where prostatic cancer occurs most frequently. There were 80 000 new cases of adenocarcinoma of the prostate in the USA in 1983, with 24 100 deaths. Prostatic cancer, therefore, represents the third most frequent cause of death from cancer in men in the USA, carcinoma of the lung and colorectal carcinoma being the two most common, and represents 10% of all deaths from cancer in men. Of the 7172 deaths due to cancer registered in France in 1987,prostatic cancer was ranked as the second most common cause of death from cancer, after pulmonary carcinoma, in men. 11 It accounted for 9.4% of all cancer deaths in men, compared with 20.8% for pulmonary carcinoma and 9.8% for colorectal carcinoma. The unadjusted mortality rate for prostatic cancer is 15 per 100 000 men per year. The trend estimated for the period 1955 - 1980

showedamoderateincreaseofl1.5%, which is less than that recorded for the same period for pulmonary carcinoma (102%) or carcinomas of the bladder (75%). For the period 1973- 1977, France was ranked 12th on average internationally with a mortality rate of 15 per 100000 inhabitants. It was again the Scandinavian countries which provide the highest figures for the mortality rate: 20.5 per 100 000 for Sweden and 17.7 per 100000 for Norway. In the case of Japan, the mortality rate was very low at 2.3 per 100 000; Thailand and Singapore also had low mortality rates. The incidence of prostatic cancer has been increasing progressively in the Western world since the beginning of the 20th century but seems to have become stable since about 1960. Mortality has also been increasing for the last few years but less than the incidence. This may be due to an improvement in diagnosis, particularly of the early forms, or even the latent disease as well as an improvement in treatment. AETIOLOGICAL FACTORS

Genetic factors There are very wide differences in mortality from prostatic cancer in various parts of the world. Overall, this cancer is frequent in western Europe and the USA, and is far more rare in Asia, particularly in Japan. It is obvious that epidemiological data must be viewed with caution, since the quality of the medical infrastructure, median age of survival and maintenance of a cancer register are all factors that can influence any analysis. In the USA, adenocarcinoma of the prostate occurs earlier and more frequently in the Black population than among those of Hispanic or Asian origin; incidence and mortality are both 50% higher in Blacks than in Caucasians. There is an increase in the incidence of prostatic cancer in relatives of patients with the disease but no particular histocompatibility locus antigen haplotype has been demonstrated. It is dif5

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B. Debre, M. Geraud, T. Flam et al.

ficult to differentiate the roles played by a possible genetic factor and environmental factors. It should be noted, however, that the incidence of prostatic cancer is intermediate in immigrants from areas of low risk who go to live in high-risk areas: for example, Japanese immigrants living on the west coast of the USA.12 Other factors Until recently, epidemiological studies have provided conflicting results for risk factors associated with the disease." There is no correlation between the incidence of in situ carcinoma detected histologically and the size of an adenoma, any more than there is a correlation between the incidence of cancer of the glandular envelope remaining in patients who have undergone adenomectomy or resection and the incidence of cancer in patients without any previous history of prostatic disorders. Tobacco and dietary factors have not been shown to have a statistically significant effect. Cancer and sexual behaviour. Numerous studies have been made concerning marital status, precocity, and frequency and duration of sexual activity, as well as the number of partners, venereal diseases and fertility.?,14 The results of these investigations are very contradictory and none of the factors can be singled out as having a dominant influence. Several studies, however, have emphasized that there is an increased risk in the case of extramarital sex. The carcinogenic role played by small calculi inside the prostate and by infections of the prostate parenchyma remains hypothetical.

induced in certain strains of rats by the chronic administration of oestrogens and androgens. In addition, carcinoma is frequently associated with atrophy of the prostate found on histological examination. Differences have been found between normal subjects and patients with carcinoma of the prostate as far as plasma testosterone, dihydrotestosterone cortisol, growth hormone, oestradiol and oestrone concentrations are concerned. In fact, it seems that androgens may help to support the prostatic epithelium and any malignant transformation must be related to some other cause. Furthermore, carcinoma of the prostate might be more frequent in patients showing greater sexual activity and increased fertility. It is interesting to note that prostatic cancer is less frequent in patients with cirrhosis who have increased oestrogen levels. It is postulated, in fact, that the likelihood of an individual developing prostatic cancer is determined early in life when his 'hormonal profile' is constituted. Viral factors. Paulson et al:" showed that the DNA virus Simian 40 can induce malignant transformation in cultured hamster prostate cells, although an equivalent effect has not been proven in man. Similarly, one strain of Herpes simplex virus (HSV -7) has been shown to induce prostatic cancer in embryonic hamster cells in vitro,17 whereas cytomegalovirus induced carcinomas of the prostate in human cells in vitro. In addition, RNA viruses and reverse transcriptase activity have been found in certain cases of the disease. CONCLUSION

Hormonalfactors. The influenceof hormones has been widely studied because of the abundance of clinical and experimental data available. 15 It has been shown that most causes of prostatic cancer are androgendependent, that prostatic cancer does not occur in eunuchs and that the cancer may be

A review of the aetiological factors involved in prostatic cancer suggests that there is no known positive risk factor. Adequate prophylactic measures are impossible and the field is wide open in the future for the application of epidemiological, metabolic and biochemical studies.

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Epidemiology of prostatic cancer REFERENCES 1. Waterhouse J, Doll R, Payne P, et al: Cancer Incidence in Five Continents UICC et CIRCe.

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tal carcinoma of the prostate: a review of literature and critical reappraisal of classification. J Uro/1980; 124: 626-631. Segi M, Kurihara M. Cancer Mortality for Selected Countries 1973 - 1978. Nagopa: Japan Cancer Society, 1984. Hatton F. Statistiques definitives des causes medicales de deces, Annee 1982. Service commun No 8. Le Vesinet: Inserm, 1984. Haenszel W. Studies of migrant populations. Am J Public Health 1985; 75: 225 - 226. Yu H: Case control study of prostate cancer and socioeconomic factors. Prostate 1988; 13: 317 325. Krain L: Epidemiologie variable in prostatic cancer. Geriatrics 1973; 93: 28. Prick J, Bartsch G: Hormonal Status in Prostatic Disease. New York: Alan R. Liss, 1976; pp143158. Paulson OF, Rabson AS, Fraley EE. Viral neoplastic transformation of hamster prostate tissue in vitro. Science 1968; 159: 200. Herbet IT, Birkhoff JO, Feorino PM, et al: Herpes simplex virus type 2 and cancer of the prostate. J Uro/1976; 116: 611- 612.

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Epidemiology of prostatic cancer.

The worldwide incidence of prostatic cancer derived from data published by the Union Internationale contre le Cancer and the International Red Cross C...
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