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Oophorectomy may increase colorectal cancer risk
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Women who underwent oophorectomy for benign indications appeared at greater risk for colorectal cancer, according to the results of a population study conducted in Sweden.
Data have shown that hormonal factors may influence the development of colorectal cancer, according to study background.
“Prospective studies have shown an 80% decrease in serum estradiol levels following bilateral oophorectomy before natural menopause,” Josefin Segelman, MD, PhD, senior consultant colorectal surgeon at Karolinska University Hospital in Stockholm, and colleagues wrote. “Androgen levels decrease by 50% after bilateral oophorectomy in both premenopausal and postmenopausal women. Whether these biological factors alter colorectal cancer risk is not clear.”
Segelman and colleagues sought to examine whether a link existed between increased colorectal cancer risk and surgical ovary removal. They used the Swedish Patient Registry to identify 195,973 women who underwent oophorectomy between 1965 and 2011, then calculated standardized incidence ratios for colorectal cancer risk in this cohort compared with the general population.
The researchers stratified data based on type of oophorectomy (unilateral vs. bilateral), as well as by hysterectomy status, age at oophorectomy (15 years to 39 years; 40 years to 49 years; 50 years to 59 years; and 60 years to 85 years) and procedure time intervals (1965-1984, 1985-1994, 1995-2004, and 2005-2011).
With a median follow-up of 18 years, 1.6% (n = 3,150) of the cohort received a diagnosis of colorectal cancer at a later date. This represented an increased risk compared with the general population (SIR = 1.3; 95% CI, 1.26-1.35), with an incidence of 91.2 per 100,000 person-years.
The majority of women diagnosed (n = 1,140) had cancer in the proximal colon. Other women had cancer in the distal colon (n = 796), colonic cancer with unspecified location (n = 213) or rectal cancer (n = 1,001).
SIRs increased with age, from 1.1 for women aged 15 to 39 years to 1.26 for women aged 40 to 49 years (P < .001 for trend).
Women who underwent bilateral oophorectomy had a higher risk for colorectal cancer than those who underwent unilateral oophorectomy (SIR = 1.35 vs. SIR = 1.2).
The highest risk period occurred 1 year to 4 years after surgery (SIR = 1.66; 95% CI, 1.51-1.81; P < .001 for trend).
A multivariable analysis showed that bilateral oophorectomy served as a stronger predictor of rectal cancer than unilateral oophorectomy (HR = 2.28; 95% CI, 1.33-3.91). Possible oophorectomy — defined as hysterectomy without specification of ovarian resection — served as a significant predictor of cancer in the distal colon (HR = 2.52; 95% CI, 1.48-4.29) and rectum (HR = 2.08; 95% CI, 1.27-3.41), as well as overall colorectal cancer (HR = 1.26; 95% CI, 1-1.6).
“In this nationwide cohort study, women who had undergone oophorectomy for benign indications had a 30% increased risk for colorectal cancer compared with the general population,” Segelman and colleagues wrote. “The reported increased colorectal cancer risk after oophorectomy in the total cohort emphasizes that prophylactic resection of normal ovaries should be reserved for women with a clear indication.” – by Cameron Kelsall
Disclosure: The researchers report no relevant financial disclosures.
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