Population-based case-control study of association of birth by cesarean delivery and development of early-onset colorectal cancer

The incidence of early-onset colorectal cancer (EO-CRC, before age 50 years) has increase worldwide. Gut dysbiosis throughout the life course is hypothesized as a leading mechanism, yet epidemiologic data are limited. A nationwide,population-based case-control study in Sweden examined the association between birth cesarean delivery and EO-CRC among offspring. Birth by cesarean delivery was not associated with EO-CRC compared with birth by vaginal delivery in the overall population (aOR 1.28; 95% CI 0.91-1.79). However, females born by cesarean delivery had greater odds of EO-CRC compared with females born through vaginal delivery (aOR 1.62; 95% CI 1.01-2.60) while there was no association for males (1.05; 0.64-1.72). The authors conclude that these findings suggest that early-life dysbiosis may contribute to EO-CRC in females.