Prostate cancer : epidemiological studies

Abstract: Prostate cancer is a large and increasing medical problem both in Sweden and in the rest of the developed world, with about 300.000 new cases diagnosed world wide annually. Despite the high incidence of this disease, little is known about the aetiology of prostate cancer. The aim of this study was to try to understand more about the natural history and to find possible a etiological risk factors for this tumour.In a population based study of prostate cancer cases in northern Sweden it was found that the large increase in prostate cancer during the last two decades was mainly caused by well (Gl) and moderately (G2) differentiated tumours. However, the incidence of poorly differentiated (G3) tumours remained unchanged. The introduction of new diagnostic methods is the most plausible explanation for the increase of these low grade tumours.The relative survival in prostate cancer was found to be independent of patient age at diagnosis, indicating that tumour proliferation and the aggressiveness of this disease is equal in all ages. However, due to the increasing occurrence of concurrent diseases with growing age the number of lost years caused by prostate cancer decreases dramatically in older age groups. The overall cause specific mortality for prostate cancer was found to be around 50%. In accordance with most other cancer tumours, the annual mortality rate decreased with longer survival also for prostate cancer patients.In a study from the Swedish Twin Register it was found that the proband concordance rates for prostate cancer were 4,5 time greater among monozygotic compared to dizygotic twins. In a large nation-wide cohort study of men who had a father with prostate cancer, the overall standardised incidence ratio (SIR) was 1.70 for prostate cancer. Younger age at diagnosis among the fathers were associated with an increased risk among sons. This cohort study and the twin study indicates that both inherited and familial factors are of importance in a subgroup of prostate cancer patients.In a prospective case-control study, both a high body mass index (BMI) and a high food intake were found to be independent risk factors for prostate cancer. Both BMI and a high food intake might be indicators of a high fat diet, which so far is the most consistent exogenous risk factor for prostate cancer. The use of tobacco or alcoholic beverages were not associated with prostate cancer risk.