Oophorectomy Associated With 30% Increased Risk of Colorectal Cancer

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Women who underwent bilateral oophorectomy were at greater risk than those who only had 1 ovary removed.
Women who underwent bilateral oophorectomy were at greater risk than those who only had 1 ovary removed.

Women who undergo oophorectomy for benign indications are more likely to develop colorectal cancer, according to Swiss researchers' population-based analysis of nearly 50 years of medical records.1

“This study supports other studies that show a connection between estrogen and colorectal cancer risk,” said Electra Paskett, PhD, MSPH, Marion N. Rowley Professor of Cancer Research at The Ohio State University College of Public Health in Columbus, in an interview with Cancer Therapy Advisor.

“It's been shown in cell cultures that estradiol and estrogen receptor agonists can cause an inhibitory effect on colorectal cancer cell growth. We have a biologic reason for why this could occur and for the association between hormone replacement therapy and colorectal cancer risk reduction—confirming the association among women who have oophorectomy.”

Dr Paskett said that women who undergo oophorectomy may need more frequent screening for colorectal cancer depending on family history and that physicians should make sure these patients understand their increased risk for the disease. She added that nothing in these results suggested that surgeons should stop performing oophorectomies for benign indications.

“It's not a done deal that just because a woman has an oophorectomy she's going to get colon cancer,” Dr Paskett said. “There are things that can be done to mitigate the risk. The important thing is we know these women are at increased risk for colon cancer, so let's inform them and change their medical management to deal with that.”

For the study, researchers reviewed records collected in the Swedish Patient Registry, the Swedish Cancer Registry, and the Cause of Death Registry for all women who underwent oophorectomy from 1965 to 2011. The team divided patients into cohorts by age at oophorectomy (ages 15–39, 40–49, 50–59, and 60–85 years) and by time at which the procedure took place (1965–1984, 1985–1994, 1995–2004, and 2005–2011). Median follow-up was 18 years.

The 195 973 women in the study had a standardized incidence ratio (SIR) of 1.30% (95% CI, 1.26 - 1.35) for colorectal cancer compared with the general population. Of the total cohort, 3150 women (1.6%) were eventually diagnosed with the disease. Women in the youngest cohort were at lower risk than the other age groups, but they were still at elevated risk compared with older women:

Age Cohort (n)

SIR (95% CI)

15-39 Years (40 774)

1.10 (0.97 - 1.23)

40–49 Years (76 358)

1.26 (1.19 - 1.33)

50–59 Years (45 060)

1.30 (1.22 - 1.39)

60–85 Years (33 781)

1.48 (1.38 - 1.60)

In multivariate analysis, women who underwent bilateral oophorectomy had a higher risk for colorectal cancer than those who had only unilateral oophorectomy (hazard ratio, 2.28; 95% CI, 1.33 - 3.91). Researchers determined that the time period women underwent oophorectomy was not statistically significant, but women were most likely to develop colorectal cancer within 4 years of the procedure (SIR, 1.66; 95% CI, 1.51 - 1.81).

Mark Welton, MD, colorectal surgeon and chief of staff at Stanford Health Care in Stanford, CA, said it was difficult to draw any conclusions from these results, noting that the authors wrote, “…no specific recommendations can be made from the present study.”

RELATED: Body Mass Index Associated With Colorectal Cancer Mortality Risk

“We see a correlation but cannot make any causation link,” Dr Welton told Cancer Therapy Advisor. “The link might simply be that patients in their 40s who undergo oophorectomy may also present with colorectal cancer through independent means in their 50s. It's hard to imagine that any sort of pathophysiology can lead to the development of cancer in 1 to 4 years. If that was the case, you would expect to see that in the age 15–39 cohort in an equal distribution as in the age 40–49 cohort.”

Editor's Note: The title of this article was changed to clarify that women who undergo oophorectomy for benign indications are more likely to develop colorectal cancer.

Reference

  1. Segelman J, Lindström L, Frisell J, Lu Y. Population-based analysis of colorectal cancer risk after oophorectomy. Br J Surg. 2016;103(7):908-915.

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