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Low-dose tamoxifen reduces recurrence of breast intraepithelial neoplasia
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SAN ANTONIO — Use of low-dose tamoxifen reduced risk for recurrence among a cohort of women who underwent treatment for breast intraepithelial neoplasia, according to results from the randomized phase 3 TAM-01 trial presented at San Antonio Breast Cancer Symposium.
The regimen also appeared safe.
“We have shown that 5 mg daily tamoxifen for 3 years halves the risk for recurrence of breast intraepithelial neoplasia in line with the effect of higher-dose tamoxifen,” Andrea DeCensi, MD, director of the medical oncology unit at National Hospital E.O. Ospedali Galliera — S.C. Oncologia Medica in Genoa, Italy, said during a press conference. “These results have external validity and are generalizable.”
Intraepithelial neoplasia accounts for approximately 20% of all breast neoplasms, including ductal carcinoma in situ, lobular carcinoma in situ (LCIS) and atypical ductal hyperplasia (ADH), DeCensi said.
Patients with breast intraepithelial neoplasia are at significantly increased risk for invasive disease.
Standard treatment includes surgery followed by tamoxifen dosed at 20 mg daily for 5 years, with subsequent radiotherapy used when needed. However, side effects of tamoxifen — including endometrial cancer, deep vein thrombosis and menopausal symptoms — represent an important barrier for use by those at increased risk for breast cancer, and the minimal active dose of tamoxifen has not been established.
DeCensi and colleagues conducted a randomized trial that included 500 women (mean age, 54 years) receiving treatment for DCIS, LCIS or ADH across 14 centers in Italy.
Researchers assigned 253 patients to 5 mg daily tamoxifen. The other 247 patients received placebo. Treatment continued for 3 years, with a minimum 2 years additional follow-up.
Treatment groups were balanced with regard to disease type, BMI, menopausal status, HER2 status and receipt of radiotherapy.
Incidence of invasive breast cancer or DCIS served as the primary endpoint.
At median follow-up of 5.1 years, researchers observed a 52% decrease in the cumulative risk for breast intraepithelial neoplasia recurrence with low-dose tamoxifen. Researchers observed 14 primary events in the low-dose tamoxifen group vs. 28 events in the placebo group (HR = 0.48; 95% CI, 0.26-0.92).
DeCensi also reported a significant decline in contralateral breast cancer cases in the low-dose tamoxifen group (12 vs. 3; HR = 0.24; 95% CI, 0.07-0.87).
“However, this analysis is only based upon 15 events, so we need to be cautious,” he said.
One patient treated with low-dose tamoxifen was diagnosed with endometrial cancer. There was one case of DVT in the tamoxifen group and one case of pulmonary embolism in the placebo group.
Researchers reported no significant differences in daily hot flashes, vaginal dryness/pain at intercourse, or musculoskeletal pain/arthralgia.
“When we compare our low-dose tamoxifen data with results from the NSABP B-24 and NSABP-P1 trials of tamoxifen given at 20 mg per day, we see comparable risk reduction and significantly reduced serious adverse events,” De Censi said. “[Although] the 5 mg tablets are not currently available, the 10 mg tablet can be cut in half or used in full every other day and is applicable in clinical practice today.” – by Jennifer Southall
Reference:
DeCensi A., et al. Abstract GS03-01. Presented at: San Antonio Breast Cancer Symposium; Dec. 4-8, 2018; San Antonio.
Disclosures: The study was funded by the Italian Ministry of Health, the Italian Association for Cancer Research, and the Italian League Against Cancer. DeCensi reports no relevant financial disclosures. Please see the abstract for all other authors’ relevant financial disclosures.