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Although colorectal cancer (CRC) is a major cause of cancer fatality in women, whether CRC outcomes differ by sex has not been investigated. To address this issue, researchers conducted a large, prospective cohort study of new invasive CRC cases that were diagnosed in Sydney, Australia, from 1997 through 2004.
Of 2050 CRC cases, 44% occurred in women. Tumors in women were more likely to be at or proximal to the splenic flexure than were tumors in men (42% vs. 32%; P<0.001), and the proportion of women, but not men, with proximal tumors increased significantly with age. Women with CRC were significantly more likely to require emergency surgery than were men with CRC (19% vs. 15%). CRC was more often fatal in women (76% vs. 68%; P=0.02), a finding that was independent of age; of receipt of emergency surgery; and of tumor site, grade, and stage. Among younger patients (age, ≤50), 5-year cancer-specific survival was higher in women than in men, regardless of the aforementioned variables (hazard ratio, 0.46). In contrast, among older patients, CRC mortality was higher in women than in men (HR, 1.38).
Koo JH et al. Improved survival in young women with colorectal cancer. Am J Gastroenterol 2008 Jun; 103:1488.
Comment
The authors considered age 50 to be a proxy for menopause and speculated that protective effects of sex steroids (demonstrated by the Women’s Health Initiative; JW Womens Health Aug 7 2002) explained why CRC-specific survival was longer in younger women. The interactions between sex steroids and CRC clearly merit additional research, especially as these investigators could not analyze reproductive history or use of exogenous hormones. The observation that more tumors in women were proximal (and thus more likely to be diagnosed late) could explain why emergency surgery was required more often in women. The relatively high prevalence of proximal tumors in women reminds us that flexible sigmoidoscopy might not be an appropriate screening strategy for both sexes.