Risk of colorectal cancer with hysterectomy and oophorectomy: A systematic review and meta-analysis

• Risk of CRC was increased for women undergoing hysterectomy or oophorectomy.
• Given that 300,000 women without susceptibility genes for ovarian cancer or metrocarcinoma undergo oophorectomy or hysterectomy every year, the association of oophorectomy or hysterectomy with increased morbidity of CRC in the entire population has implications for public health guidance.
• Lacking randomized controlled trials, these high-quality cohort studies with large size and high follow-up rate of long-term follow-up offer a good method to assess these associations.
• This meta-analysis is the first to evaluate these controversial results.

BackgroundColorectal cancer (CRC) is the second most commonly diagnosed cancer worldwide in females. Sex hormones may play a protective effect in CRC pathogenesis. Ovarian sex steroid levels are reduced in premenopausal women after hysterectomy. Prospective studies have revealed an 80% decrease in serum oestradiol levels after bilateral oophorectomy in premenopausal women. We aimed to elucidate the relationship between hysterectomy or oophorectomy and risk of CRC.MethodsWe estimated relative risk (RR) and 95% confidence intervals (95% CIs) with the meta-analysis. Cochran's Q test and Higgins I2 statistic were used to check for heterogeneity. Subgroup and sensitivity analyses were performed as were Egger's and Begg's tests and the “trim-and-fill” method for publication bias analysis.ResultsRisk of CRC was increased 30% for women undergoing oophorectomy relative to the general population and 24% with hysterectomy relative to no surgery. The risk was increased 22% with hysterectomy with bilateral salpingoo-ophorectomy as compared with simple hysterectomy. On subgroup analysis, risk of rectal cancer was increased 28% and colon cancer 19% with hysterectomy. Europeans seem to be sensitive to the risk of CRC, with 27% increased risk after hysterectomy. The risk of CRC after oophorectomy gradually increased with age at oophorectomy. The risk was greater with bilateral oophorectomy, with 36% increased risk, than unilateral oophorectomy, with 20% increased risk. Risk was increased 66% with time since oophorectomy 1–4 years as compared with 5–9 and ≥ 10 years.ConclusionsRisk of CRC was increased for women undergoing hysterectomy or oophorectomy. Women with susceptibility genes for ovarian cancer or metrocarcinoma should choose oophorectomy or hysterectomy. For women not at high risk for these cancers, oophorectomy or hysterectomy should not be recommended for increasing the subsequent risk of CRC.