Hormone therapy associated with reduced colorectal cancer risk
The combination of estrogen plus progestin, which women stopped taking in droves following the news that it may increase their risk of breast cancer, may decrease their risk of colorectal cancer, according to a report published in the January issue of Cancer Epidemiology, Biomarkers and Prevention, a journal of the American Association for Cancer Research. "Compared to women who had never taken these hormones, the use of estrogen plus progestin was associated with a reduced risk of colorectal cancer," said Jill R. Johnson, M.P.H., a doctoral student at the University of Minnesota School of Public Health.
The largest risk reduction, approximately 45 percent, was seen among women who had completed use of estrogen plus progestin five or more years previously.
Johnson and her colleagues extracted data from 56,733 postmenopausal women who participated in the Breast Cancer Detection Demonstration Project follow-up study. Hormone therapy use and other risk factors were ascertained through telephone interviews and mailed questionnaires between 1979 and 1998. During an average 15 years of follow-up, Johnson and colleagues identified 960 new cases of colorectal cancer in this population.
Any use of estrogen therapy was associated with a 17 percent reduced risk in colorectal cancer. Among those who used estrogen, the largest reductions were seen among those who were current users (25 percent reduced risk) and users of ten or more years duration (26 percent reduced risk).
Researchers also found a 22 percent reduced risk among those who had ever used estrogen plus progestin in combination. They further found a 36 percent reduction in risk among those who had used progestin sequentially or less than 15 days per month. Past users of estrogen plus progestin, who had stopped at least five years ago, had a 45 percent risk reduction.
Although Johnson's study was not designed to look at biological mechanisms for the protective effect of estrogen therapy, she did say that previous research has suggested that hormones may play a role in decreasing levels of insulin-like growth factors, thereby reducing risk. "The biological mechanism will need to be explored in further studies," said Johnson.
Articles on the same topic
- Study links obesity to elevated risk of ovarian cancerMon, 5 Jan 2009, 3:21:44 EST
- Hormone therapy associated with reduced colorectal cancer riskfrom PhysorgThu, 8 Jan 2009, 6:16:21 EST
- Study Links Obesity to Ovarian Cancerfrom NY Times HealthWed, 7 Jan 2009, 12:00:29 EST
- Obesity elevates risk of ovarian cancerfrom Science BlogWed, 7 Jan 2009, 6:42:35 EST
- Obesity Linked To Elevated Risk Of Ovarian Cancerfrom Science DailyMon, 5 Jan 2009, 12:28:42 EST
- Obesity elevates risk of ovarian cancerfrom Science BlogMon, 5 Jan 2009, 8:56:15 EST
- Study links obesity to elevated risk of ovarian cancerfrom PhysorgMon, 5 Jan 2009, 3:21:13 EST
Latest Science NewsletterGet the latest and most popular science news articles of the week in your Inbox! It's free!
Learn more about
Check out our next project, Biology.Net
From other science news sites
Popular science news articles
- Oceans may be large, overlooked source of hydrogen gas
- Mars rover's laser can now target rocks all by itself
- Researchers map Zika's routes to the developing fetus
- Here's why run-down schools trigger low test scores
- UTMB researchers find first direct evidence that A. aegypti mosquito transmits Zika virus