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For women diagnosed with hormone-receptor-positive DCIS, a new study has determined that low dose Tamoxifen after surgery reduced the risk of the disease coming back. Low dose tamoxifen also reduced the risk of developing a new invasive breast cancer.

DCIS is part of the spectrum of Breast Intraepithelial Neoplasia, a collection of breast diseases, in which abnormal breast cells are found within the breast ducts or lobules. Breast Intraepithelial Neoplasia includes ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS), atypical ductal hyperplasia (ADH) and atypical lobular hyperplasia (ALH). These conditions significantly increase a woman’s risk of developing invasive breast cancer.

Tamoxifen is a drug that is often effective for breast cancer prevention and treatment, but the risk of endometrial cancer and venous thromboembolism (blood clots), as well as other adverse  side-effects, has limited its broader use. Previous studies have demonstrated in biomarker trials that the minimal effective dose of tamoxifen is lower than 20 mg/day, but a clearer answer on safety and effectiveness required a phase III, i..e. more advanced, clinical trial.

In the phase III “TAM-01” trial, 500 women with hormone sensitive breast intraepithelial neoplasia (DCIS or LCIS) were randomly selected to either be given Tamoxifen 5mg a day or a daily placebo (sugar pill), after surgical removal of their lesion. The women were seen every 6 months with annual mammography for at last 5 years after beginning the trial.

Encouraging Results

The findings revealed that Tamoxifen at this low dose reduced the risk of recurrence or new disease by 52% in women with hormone sensitive DCIS or LCIS. Toxicity was limited and thus low dose tamoxifen provides a valid treatment option for women with DCIS or LCIS. In addition, this study has important implications for possible preventative therapy of high-risk unaffected women, i.e. women with Breast Intraepithelial Neoplasia or a family history of breast cancer.

Regarding side-effects, women taking the low dose of Tamoxifen had minimally more side effects than women who were taking the placebo. Women taking Tamoxifen reported more hot flashes than women who were taking placebo, but this difference was small and not statistically significant, which means that it could have been due to chance rather than because of the treatment.

If you’ve been diagnosed with DCIS, LCIS, ADH or ALH and are weighing treatments after surgery, you may want to ask your doctor about the TAM-01 study and whether a daily, low dose of Tamoxifen would be a good fit for you.

In addition, if you’d like to discuss the most advanced surgical treatments for breast cancer, consult with Dr. Aaron Margulies. Committed to serving breast cancer patients through his solo practice in Breast Surgical Oncology and General Surgery, Dr. Margulies has offices at Tennova Turkey Creek Medical Center in West Knoxville, at Tennova North Knoxville Medical Center in Powell, at Jefferson Memorial Hospital, and in Newport. His extensive research and expertise have distinguished him as a leader in the field. To learn more about Dr. Margulies’ compassionate surgical care approach visit www.aaronmd.com or call (865) 692-1610.