• Posted December 16, 2024

Study Supports Tamoxifen for DCIS Early Breast Cancers

The established hormone therapy drug tamoxifen can significantly decrease the risk of cancer recurring in women with an early, low-risk form of breast cancer, a new study says.

Women who took tamoxifen after undergoing a lumpectomy to remove ductal carcinoma in situ (DCIS) were 44% to 51% less likely to have their cancer return in that breast, researchers reported last week at the annual San Antonio Breast Cancer Symposium (SABCS).

The risk of cancer returning is one of the most important factors that doctors and patients weigh following DCIS surgery, said researcher Dr. Jean Wright, chair of radiation oncology at the University of North Carolina.

Until now, it hasn’t been clear whether tamoxifen could help prevent cancer from coming back in this group of patients, Wright said in an SABCS news release.

“This finding, in such a robust data set, is clarifying,” Wright said.

"Tamoxifen, radiation or both, as well as the omission of any adjuvant therapy, are all reasonable options,” Wright added. “Now, we have more data to help our patients choose among these.”

DCIS involves abnormal cells found within a milk duct in the breast. It’s an early, noninvasive form of breast cancer that accounts for about 20% to 25% of all new breast cancer cases in the United States, according to the National Breast Cancer Foundation.

Tamoxifen has been used for more than 40 years to treat breast cancers that are fueled by the female hormone estrogen, according to the Susan G. Komen Foundation. It works by blocking estrogen receptors in cancer cells, 

For this study, researchers combined data from two clinical trials to evaluate outcomes for nearly 900 women treated for low-risk DCIS. About 43% of the women received tamoxifen after undergoing breast-conserving surgery to remove their cancer.

Women who received tamoxifen had an 11% risk of cancer recurring in the breast with DCIS, compared to 19% for women who didn’t take the drug, results showed.

When adjusted for the size of their DCIS, patients who took tamoxifen were 44% less likely to experience recurrence, results show.

Likewise, when adjusted for DCIS grade, the tamoxifen patients were 51% less likely to have their cancer come back. Grade refers to how abnormal cancer cells look under a microscope -- the higher the grade, the faster the cancer is likely to grow and spread.

These findings support current guidelines from the National Comprehensive Cancer Network, which advises that women who receive a lumpectomy for DCIS consider tamoxifen after surgery, researchers noted.

“The more information we can provide patients about the impact of specific treatments, the more we can empower patients to make choices that are right for them,” Wright said in a news release. “I believe that being able to provide clear information to our patients leads to the best care.”

More information

The National Breast Cancer Foundation has more on DCIS.

SOURCE: San Antonio Breast Cancer Symposium, news release, Dec. 12, 2024