Analysis of sex-related differences in cancer incidence among solid organ transplant recipients

Males have 2-3 fold greater risk of cancer than females at most shared anatomic sites, possibly reflecting enhanced immune surveillance against cancer in females. Analysis of the Transplant Cancer Match Study estimated the male-to-female incidence rate ratio (M:F IRR_Transplant) for 15 cancer sites, while analysis of the SEER database estimated this ratio in the general population (M:F IRR_GP). An excess cancer incidence in males was seen in transplant recipients but the sex difference in transplant recipients was attenuated compared to the general population for cancers of the lip, stomach, colorectum, liver, kidney, bladder, Kaposi sarcoma, and non-Hodgkin lymphoma. The M:F IRR_Transplant was not statistically different from the M:F IRR_GP for other cancer sites. The authors conclude that the attenuation of the M:F ratio in recipients of solid organ transplant for many cancer studied relative to the general population might suggest the importance of immunosurveillance, with some loss of advantage in females due to immunosuppression following transplantation.