title: Risk of colorectal cancer with hysterectomy and oophorectomy: A systematic review and meta-analysis.
abstract: BACKGROUND
  Colorectal 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.
  
  
  METHODS
  We estimated relative risk (RR) and 95% confidence intervals (95% CIs) with the meta-analysis. Cochran's Q test and Higgins I2statistic 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.
  
  
  RESULTS
  Risk 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.
  
  
  CONCLUSIONS
  Risk 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.
authors: Department of Public Health, Shantou University Medical College, No.22 Xinling Road, Shantou, Guangdong, 515041, China. Electronic address: luoganfeng1991@126.com.
authors: Ganfeng
authors: G
authors: Luo
authors: Department of Public Health, Shantou University Medical College, No.22 Xinling Road, Shantou, Guangdong, 515041, China. Electronic address: zhangyanting1992@126.com.
authors: Yanting
authors: Y
authors: Zhang
authors: Department of Public Health, Shantou University Medical College, No.22 Xinling Road, Shantou, Guangdong, 515041, China. Electronic address: wangli3740@126.com.
authors: Li
authors: L
authors: Wang
authors: Department of Public Health, Shantou University Medical College, No.22 Xinling Road, Shantou, Guangdong, 515041, China. Electronic address: hywwell@126.com.
authors: Yuanwei
authors: Y
authors: Huang
authors: Department of Public Health, Shantou University Medical College, No.22 Xinling Road, Shantou, Guangdong, 515041, China. Electronic address: qy_yu1990@126.com.
authors: Qiuyan
authors: Q
authors: Yu
authors: Department of Public Health, Shantou University Medical College, No.22 Xinling Road, Shantou, Guangdong, 515041, China. Electronic address: guopi.01@163.com.
authors: Pi
authors: P
authors: Guo
authors: Department of Public Health, Shantou University Medical College, No.22 Xinling Road, Shantou, Guangdong, 515041, China. Electronic address: keli1122@126.com.
authors: Ke
authors: K
authors: Li
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000209:etiology*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood; D006801:Humans; D007044:Hysterectomy / Q000009:adverse effects*; D008875:Middle Aged; D010052:Ovariectomy / Q000009:adverse effects*; D017697:Premenopause / Q000097:blood; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D012739:Gonadal Steroid Hormones
keywords: Colorectal cancer; Hysterectomy; Meta-analysis; Oophorectomy; Relative risk