WILMINGTON, Del—After the publicity surrounding the Breast Cancer Prevention Trial (BCPT), many doctors were besieged by questions from women about whether to take tamoxifen(Drug information on tamoxifen) (Nolvadex) to reduce their breast cancer risk. The queries may accelerate now that Nolvadex has received FDA approval for this use. A new software program from the National Cancer Institute can help by providing an easy way to estimate a woman’s 5-year and lifetime breast cancer risk.
“It’s an honest software program that most any physician can use,” said Jerry Lewis, MD, of Zeneca Pharmaceuticals, manufacturer of Nolvadex, which is helping to distribute the software.
The program, called the Breast Cancer Risk Assessment Tool, was developed from data on women who underwent mammography and had their risk of breast cancer observed. The program asks each woman and her doctor to answer seven questions about her medical history. Based on the answers, it assigns the woman a score on a risk table.
“The software accurately reflects most women’s risk of breast cancer and is especially good for women who are anxious about their risk,” Dr. Lewis said in an interview. “If a woman finds she has an elevated risk [1.67 or higher on the risk table, meaning a 1.67% chance of developing breast cancer in the next 5 years], then it’s time for her to discuss with her physician the best ways to prevent the disease,” he said. “Patients and physicians can work together to schedule increased mammography screenings and consider use of preventive medications like tamoxifen.”
The software asks the patient about her history of breast abnormalities, age, age at menarche, age at first live birth, history of breast cancer among first-degree relatives, breast biopsies, and race.
Other possible risk factors were left out—such as age at menopause, use of hormone replacement therapy, a high-fat diet, and exposure to environmental pollutants—because these factors were not addressed in the database used to determine risk. “The degree of risk for these factors cannot be determined precisely or is simply not available,” he said.
The assessment tool is not accurate for women with a history of breast cancer or those with a BRCA1 or BRCA2 gene mutation. But it can provide other at-risk women with important clues about whether to use tamoxifen.
“Many women are very afraid of breast cancer, uterine cancer, and blood clots—and so a woman with increased breast cancer risk has to consider tamoxifen’s benefits and side effects carefully. But for many at-risk women, the benefits of tamoxifen far outweigh its problems,” Dr. Lewis said.
In the BCPT, breast cancer was diagnosed half as often in women who took tamoxifen as in those on placebo. Women older than 50 who took tamoxifen, however, also were at increased risk for three rare but serious side effects: endometrial cancer, pulmonary embolism, and deep vein thrombosis.
Endometrial Cancer Risk
The BCPT results showed that women over age 50 on tamoxifen had about four times the risk of developing endometrial cancer as women the same age not taking the drug. The risk with tamoxifen was equivalent to about 30 cases of endometrial cancer a year for every 10,000 women in the population vs 8 cases per 10,000 women without tamoxifen.
The trial also showed that a woman’s risk of developing blood clots while on tamoxifen was in the range of a woman taking birth control pills or estrogen replacement therapy. Women who are pregnant, who plan to become pregnant, or who are at increased risk for blood clots should not take tamoxifen to reduce their incidence of breast cancer. Women on tamoxifen must not take birth control pills or hormone replacement therapy at the same time, Dr. Lewis said.
To receive the assessment software free of charge, call 1-800-4-CANCER or visit the NCI’s cancer trials website at http://cancerTrials.nci.nih.gov.
