Long‐term cancer risk after hysterectomy on benign indications: Population‐based cohort study

Hysterectomy on benign indications is associated with an increased risk for adverse health effects. However, little is known about the association between hysterectomy and subsequent cancer occurrence later in life. The purpose of this study was to assess the effect of hysterectomy on the incidence of cancer. In this population‐based cohort study, we used data on 111,595 hysterectomized and 537,9843 nonhysterectomized women from nationwide Swedish Health Care registers including the Inpatient Register, the Cancer Register and the Cause of Death Register between 1973 and 2009. Hysterectomy with or without concomitant bilateral salpingo‐ophorectomy (BSO) performed on benign indications was considered as exposure and incidence of primary cancers was used as outcome measure. Rare primary cancers (<100 cases for the two groups combined) were excluded from analysis. A marginal risk reduction for any cancer was observed for women with previous hysterectomy and for those with hysterectomy and concurrent BSO (HR 0.93, 95% CI 0.91–0.95 and HR 0.92, 95% CI 0.87–0.96, respectively). Compared to nonhysterectomized women, significant risks were observed for thyroid cancer (HR 1.76, 95% CI 1.45–2.14). For both hysterectomy and hysterectomy with BSO, an association with brain cancer was observed (HR 1.48, 95% CI 1.32–1.65 and HR 1.45, 95% CI 1.15–1.83, respectively). Hysterectomy, with or without BSO, was not associated with breast, lung or gastrointestinal cancer. We conclude that hysterectomy on benign indications is associated with an increased risk for thyroid and brain cancer later in life. Further research efforts are needed to identify patient groups at risk of malignancy following hysterectomy.