HRT use cuts colon cancer risk but linked to more advanced disease

Postmenopausal women who use estrogen and progestin appear to have a decreased risk of colorectal cancer, data from the Women’s Health Initiative (WHI) trial indicate. However, the cancers that do occur seem to be more advanced than those seen in non-HRT users.

Most of the news regarding HRT in recent years has been bad. Just this week, the National Institutes of Health announced that the estrogen-only arm of the Women’s Health Initiative (WHI) trial was being stopped early after the therapy was tied to an increased risk of stroke. This follows the termination of the estrogen/progestin arm in 2002 due to an observed increase in breast cancer, thrombosis, stroke, and heart disease events among HRT users (see Reuters Health reports March 2, 2004 and July 9, 2002).However, when the estrogen/progestin arm was stopped, the WHI researchers did notice one potentially beneficial effect for HRT — a decreased risk of colorectal cancer, according to a report published in The New England Journal of Medicine for March 4.To better understand the link between HRT use and colorectal cancer, Dr. Rowan T. Chlebowski, from Harbor-UCLA Medical Center in Torrance, California, and colleagues analyzed data from 16,608 postmenopausal women who participated in the estrogen/progestin arm of WHI. Overall, HRT users were 44% less likely to develop colorectal cancer than non-users (p = 0.003), the researchers found. “We were quite surprised to find that colon cancers in HRT users were of higher stage than those seen in controls,” Dr. Chlebowski told Reuters Health. The cancers that occurred in HRT users had a greater number of positive lymph nodes (p = 0.002) and were more likely to show regional or metastatic involvement (p = 0.004), the analysis indicates. “Our findings are somewhat similar to what was seen in the trial with finasteride and prostate cancer — overall risk is decreased but severe disease is more likely,” Dr. Chlebowski noted (see Reuters Health report June 24, 2003). However, “in that trial, finasteride use was tied to higher grade tumors, whereas in ours, HRT use was linked to advanced stage disease but not to higher grade tumors,” he added.”Interestingly, among HRT users with colon cancer, those with antecedent vaginal bleeding were the ones most likely to have advanced stage disease,” Dr. Chlebowski pointed out. “This may have resulted from a delay in diagnosis.”Despite all the unfavorable reports, Dr. Chlebowski believes that HRT could still be a viable therapy. “One strategy would be to see if the risks of HRT could be modulated with other agents,” he added.(Source: N Engl J Med 2004;350:991-1004: Reuters Health: Anthony J. Brown, MD: March 2004: Oncolink)