In 26,136 cancer-free controls and 23,093 cancer cases drawn from non-sex specific and non-hematological cancer sites (i.e. excluding 8,470 individuals with leukemia, lymphoma, multiple myeloma and cancers of the breast, endometrium, ovary, testis, and prostate), we observed a higher frequency of males with mosaic abnormalities than females. In cancer-free individuals, we observed mosaic events in 0.56% of females and 0.87% males (OR=1.35, 0.98-1.88 95% CI, p=0.07); for individuals with cancer we observed mosaic events in 0.79% of females and 1.21% of males (OR=1.48, 1.08-2.03 95% CI, p=0.015); and overall, 0.65% of females and 1.04% of males (OR=1.42, 1.14-1.80 95% CI, p=0.002) in logistic models adjusted for cancer diagnosis (if applicable), age at DNA collection, ancestry, DNA source and smoking. These differences could be due to a true sex-specific effect akin to sex-differential mutation and recombination rates19; however the complex and heterogeneous nature of the inclusion of individual studies and the differences in their entry and selection criteria could result in spurious associations. Although this observation was consistent across cancer types, it should be confirmed in additional studies better designed to address this question.
