Nationwide cancer family ascertainment using Finnish Cancer Registry data on family names and places of birth for 35,761 prostate cancer patients

Abstract

Identification of predisposition loci to complex diseases, such as prostate cancer, requires high-quality family material, the ascertainment of which is often laborious, time-consuming and inaccurate with conventional methods. Here, we describe a new method for rapid, nationwide cancer family ascertainment using Finnish Cancer Registry data on 35,761 prostate cancer cases over a 40-year period. As members of a prostate cancer family are likely to share the same family name and place of birth, we stratified all prostate cancer cases by these 2 parameters (10,721 different names and 596 municipalities). Data were compared with the distribution of family names and places of birth for all 3.3 million Finnish men to derive standardized prevalence ratios (SPRs). A significantly elevated SPR of prostate cancer was detected for 468 (1.6%) of the 28,459 evaluable combinations of family name and place of birth. Of the 20 highest SPR values, 19 corresponded to true nuclear families, most of these having 3 or more affected cases. Two-thirds of our 50 previously established Finnish prostate cancer families were classified among this 1.6% fraction of the highest SPR values. Finally, many of the highest SPR values originated from municipalities in southern and south-western Finland. To explore whether such clusters could highlight local founder effects, we applied genealogical research to link together several families with elevated SPRs and identified an extended family with 20 prostate cancer cases with common ancestors in the early seventeenth century. In summary, a rapid novel method was developed and validated for identification of prostate cancer families from nationwide cancer registry data and for the identification of putative regional founder effects.