Purpose: APC I1307K has a higher prevalence among Ashkenazi Jews (AJ), and a two-fold increased risk for colorectal cancer (CRC) compared to non-Jewish populations. We assessed CRC and extracolonic malignancies among I1307K carriers from AJ and non-AJ whites (NAW). Methods: We compared the rate of I1307K in cancer patients who underwent germline genetic testing via a multi-gene panel with healthy subjects retrieved from the gnomAD database. Cases undergoing testing were not selected and testing was undertaken through a commercial laboratory. Results: Overall, 586/7624 (7.6%) AJ with cancer carried I1307K compared to 342/4918 (6.9%) in the AJ control group (p = NS). In the NAW, 318/141,673 (0.2%) cancer patients and 73/58,918 (0.1%) controls carried the variant [OR = 1.8, (95% CI 1.41−2.35), p < 0.001]. I1307K in NAW was associated with an increased risk of CRC [OR = 1.95, (95% CI 1.39−2.73), p < 0.01], melanoma [OR = 2.54, (95% CI 1.57−3.98)], breast [females, OR = 1.73, (95% CI 1.18−2.65), p < 0.01], and prostate cancer [males, OR = 2.42, (95% CI 1.45−3.94), p < 0.01]. Among AJ, the variant increased the risk for CRC [OR = 1.67, (95% CI 1.36−2.05), p < 0.001] and renal cancer [OR = 1.64, (95% CI 1.04−2.47)]. AJ men had a higher risk for any cancer [OR = 1.32, (95% CI 1.05−1.66), p < 0.05] and melanoma [OR = 2.04, (95% CI 1.24−3.22); p < 0.05]. Conclusions: This is the most extensive study to date conducted on I1307K carriers, although it is amenable to selection bias. NAW carrying I1307K had a higher risk of any cancer and several specific cancer types, whereas AJ carrying the variant had a risk for only a few select cancers. Our data add to the research base on I1307 carriers concerning future risk management.
Keywords: APC I1307K; Ashkenazi jews; CRC; cancer.