TUESDAY, Feb. 18, 2003 (HealthDayNews) -- Tamoxifen, the drug that has been shown to cut the risk of breast cancer in high-risk women, also appears to reduce the incidence of noncancerous breast disease, new research shows.
An earlier trial, the Breast Cancer Prevention Trial, part of the National Surgical Adjuvant Breast and Bowel Project (NSABP), found that tamoxifen reduced the incidence of invasive and noninvasive breast cancer by up to 50 percent.
In the current trial, reported in the Feb. 19 issue of the Journal of the National Cancer Institute, the drug reduced the incidence of benign breast disease, including fibrocystic disease and hyperplasia, by 28 percent. It also resulted in fewer biopsies.
Tamoxifen interferes with the activity of the hormone estrogen and is therefore effective in breast cancers that are estrogen-receptor positive. Estrogen receptors are also expressed in benign breast lesions, leading researchers to believe that tamoxifen might also have an effect here.
Benign breast disease can be a risk factor for later breast cancer.
"Certainly not all benign breast disease is associated with increased cancer risk, but some of the types are," says Dr. Carl Kardinal, associate section head of hematology/oncology at the Ochsner Clinic Foundation in New Orleans.
"Do benign lesions directly evolve into invasive breast cancer? The answer is no," says study author Dr. Elizabeth Tan-Chiu, director of prevention and the early stage breast cancer program at the Cancer Research Network in Plantation, Fla. "We feel that having benign breast lesions is an independent prognostic factor that tells you that your risk is increased for developing invasive breast cancer."
However, even conditions not associated with increased breast cancer risk often require biopsies because it's not easy to tell what it is by a physical exam or even a mammography. "These women very often have to undergo breast biopsies," Kardinal says. "It's not increased cancer risk but an increased risk of having to have other procedures which may not be totally necessary."
When tamoxifen was being sized up for its effect on the risk of developing breast cancer, critics faulted the study, saying that perhaps rather than preventing breast cancer, the agent was actually treating undetected tumors. "We felt that the word 'prevention' should be used in its entire context," Tan-Chiu says. "We dug deeper and were very surprised to see that even in benign breast lesions, tamoxifen had an effect. We were able to alter it at its very roots."
Here, the researchers looked at the incidence of benign breast disease and the number of biopsies among 13,203 women who were treated either with tamoxifen or a placebo within the auspices of the Breast Cancer Prevention Trial.
Women who were given tamoxifen had a 28 percent reduction in their risk of benign breast disease, including adenosis, cysts, duct ectasia, fibrocystic disease, hyperplasia and metaplasia. The tamoxifen group had 29 percent fewer biopsies compared with women in the placebo group.
The reduction in biopsies was a significant effect. "For every intervention that we reduce that's one less anxiety for a woman who has to wait for results," Tan-Chiu says. "I think that's doing something."
Most of the benefit occurred in women under the age of 50. The risk of biopsies among women 49 years and younger was cut by 41 percent, while the total number of biopsies in women 50 and over did not show a statistically significant change. This difference is probably due to hormones, Tan-Chiu says. "Breasts are still very active in premenopausal women, swelling and unswelling," she says. "I think when you're cycling the most is when you see the effect of tamoxifen."
Still, there's no good reason for women of any age to go out and start popping tamoxifen, which carries significant side effects, including stroke, endometrial cancer and pulmonary embolism.
"It's certainly not for everyone. You wouldn't go out and take a young woman who had fibrocystic disease and put her on tamoxifen because the risks are greater than the benefits," Kardinal says. "But in women who have increased breast cancer risk defined as a positive family history or having had prior breast biopsies or other factors, she may also get a secondary benefit."
The results won't affect women who still present with abnormal mammograms. "That will require a biopsy," says Dr. Carina Biggs, director of breast surgery at Maimonides Medical Center in New York City. "Those are at risk still would require a biopsy to exclude the diagnosis of cancer."
More information
For more on benign breast disease, visit the University of Michigan. The Komen Foundation has information on tamoxifen, as does the National Cancer Institute.
