"We''ve known for a while that estrogen prevents colorectal cancer, but this is the first study to suggest it may improve outcomes once you have colorectal cancer," said Heinz-Josef Lenz, M.D., co-director of gastrointestinal oncology and colorectal cancer at the University of Southern California/Norris Comprehensive Cancer Center, Keck School of Medicine.
Using the Surveillance, Epidemiology and End Results registry, Lenz and colleagues screened 52,882 patients who had metastatic colorectal cancer between 1988 and 2004.
Women age 18 to 44 years had significantly longer survival than men - at 17 months compared with 14 months. However, older women had significantly shorter overall survival at seven months compared with nine months.
Lenz said these results suggest that estrogen levels may be playing a significant role in prognosis. James Abbruzzese, M.D., chair of gastrointestinal medical oncology at the University of Texas M. D. Anderson Cancer Center and a deputy editor of Clinical Cancer Research, agreed that hormones may certainly play a role, but says a look at the data broken down by year is also intriguing. Specifically, those diagnosed after 2000 have improved survival; those diagnosed before 2000 had a less pronounced survival advantage.
"In terms of the chemotherapy we have available, since 2000 the regimens employ more agents and have become much more aggressive. Therefore, it may be expected to inhibit normal hormonal cycles leading to lower hormonal levels in these women, so other factors may be playing a role as well. It may not just be hormones," said Abbruzzese.