RISK OF CANCER IN RELATIVES OF PROSTATE-CANCER PROBANDS

Background: It is estimated that there will be more than 244000 new pr ostate cancer cases diagnosed and that more than 40000 men will die of this disease during 1995, Evidence exists for a hereditary predisposi tion to prostate cancer, but the proportion of cases attributable to t he inheritance of a specific gene or genes is not large, Some heredita ry cancer syndromes involve more than one tumor site, and some studies have reported a familial association between prostate cancer and othe r cancers, The presence of other cancers in prostate cancer families m ay indicate a specific type of hereditary predisposition, Purpose: We studied families that were selected because of the presence of prostat e cancer to determine whether hereditary prostate cancer is associated with cancers at other sites and possibly with other heritable cancer syndromes, Methods: Data from two distinct study populations were stud ied retrospectively. The first population consisted of 690 case patien ts undergoing radical prostatectomy who were not selected for family h istory of prostate cancer and 640 control subjects who were the spouse s or female companions of the case patients, The second population con sisted of 75 multiplex families (i.e., families with multiple cases of prostate cancer) referred because they fulfilled the criteria for her editary prostate cancer, A comparison between case and control populat ions for the occurrence of 14 aggregated groups of cancer was performe d, Data were analyzed using Poisson regression, and relative risks (RR s) and their 95% confidence intervals (CIs) were calculated, Results: Brothers and fathers of prostate cancer probands have a statistically significant higher risk of prostate cancer than the male first-degree relatives of control subjects (RR = 1.76; 95% CI = 1.28-2.43), Therefo re, the risk for prostate cancer is 76% higher among first-degree rela tives of prostate cancer patients compared with first-degree relatives of control subjects. This higher risk was not modified by an occurren ce of breast cancer in the pedigree, Also, a statistically significant higher risk was found for tumors of the central nervous system in her editary families (RR = 3.02; 95% CI = 1.08-8.41), Statistically signif icant higher risks of cancer at other major sites, such as breast, ova ry, or endometrium were not observed in these families, Conclusion: Ev en among families that were specifically selected because of the prese nce of prostate cancer, risks for cancer at other sites appeared not t o be increased, Therefore, hereditary prostate cancer appears to be a relatively site-specific disease, and it does not seem to be a part of other hereditary cancer syndromes.