Age, sex and the risk of grade-specific second primary colorectal cancer: Evidence for the protective effect of female hormone

AimTo investigate the interaction effects of age and sex on the risk of grade-specific second primary colorectal cancer (SPCRC).MethodThis is a retrospective cohort study, using registry data covering the period 1973–2003 from the SEER program, National Cancer Institute. The sex-age-specific incidence rates of Grade 1, Grade 2 and Grade 3 second primary colorectal cancer (SPCRC) were calculated. Poisson regression models were used to estimate the interaction effects between sex and age.ResultsThe sex-age-specific incidence rates of Grade 1, Grade 2, and Grade 3 second primary colorectal cancer (SPCRC) increased gradually with age, especially in females. There was a significant interaction effect between sex and age on the risk of Grade 3 second primary colon cancer.ConclusionDecrease in female hormone level since menopausal age may increase the risk of a second primary colon cancer, especially a cancer with poorer differentiation.