Hysterectomy and risk of breast, colorectal, thyroid and kidney cancer - an Australian data linkage study

Abstract

Background: This study aimed to investigate the associations between hysterectomy for benign indications and risk of breast, colorectal, kidney and thyroid cancer; and to explore whether these associations are modified by removal of ovaries at the time of surgery or age at surgery. Methods: We conducted a retrospective cohort study of the female population of Western Australia (n=839,332) linking data from electoral, hospital, births, deaths and cancer records. We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the associations between hysterectomy and diagnosis of breast, colorectal, kidney and thyroid cancers. Results: Compared to no surgery, hysterectomy without oophorectomy (hysterectomy) and hysterectomy-BSO were associated with higher risk of kidney cancer (HR, 1.32; 95% CI, 1.11-1.56 and HR, 1.29; 95% CI, 0.96-1.73 respectively). Hysterectomy, but not hysterectomy-BSO, was related to higher risk of thyroid cancer (HR, 1.38; 95% CI, 1.19-1.60). In contrast, hysterectomy (HR, 0.94; 95% CI, 0.90-0.98) and hysterectomy-BSO (HR, 0.92; 95% CI, 0.85-1.00) were associated with lower risk of breast cancer. We found no association between hysterectomy status and colorectal cancer. Conclusions: The associations between hysterectomy and cancer varied by cancer type with increased risks for thyroid and kidney cancer, decreased risk for breast cancer and no association for colorectal cancer. Impact: As breast, colorectal and gynaecological cancers comprise a sizeable proportion of all cancers in women, our results suggest that hysterectomy is unlikely to increase overall cancer risk; however, further research to understand the higher risk of thyroid and kidney cancer is warranted.