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Primary endocrine therapy allows most women with invasive breast cancer to avoid surgery without disease progression in the breast or symptomatic distant metastases, according to research presented at the 17th St. Gallen International Breast Cancer Conference 2021.
Lynsey Williams, from the Royal Marsden NHS Trust in Sutton, United Kingdom, and colleagues sought to analyze the long-term outcome of women who are diagnosed with estrogen receptor-positive breast cancer and who decline or are considered unfit for surgery.
The researchers conducted a database search to identify women who had invasive breast cancer and received primary endocrine therapy as their first treatment. Patients who received neoadjuvant endocrine therapy with the goal of downstaging prior to surgery or had de novo stage IV disease were excluded from consideration.
A total of 95 patients (median age, 84 years; interquartile range [IQR], 80-89) met the eligibility criteria. Participants’ median Charlson Comorbidity Index score was 7 (IQR, 6-7). Patient frailty (n=64, 67%) and patient choice (n=28, 29.5%) were the most common reasons given for primary endocrine therapy, and letrozole was the most frequently prescribed drug (n=87, 92%)
The median follow-up was 724 days (IQR, 360.5-1233). Estrogen receptor positivity with an Allred score of 8/8 was found in 93 (98%) patients, and 53 women (55.8%) were progesterone receptor-positive with a score of 8/8. No patients had HER2-positive disease. Most tumors were grade 2 (62, 65%) and ductal (72, 76%), and the median tumor size on ultrasound at diagnosis was 25 mm (IQR, 17-32).
A total of 30 women (32%) had clinical or radiologic local progression that required a change in endocrine therapy. In addition, 11 women (11.6%) underwent surgery and 6 (6.3%) underwent radical radiotherapy to the breast without surgery for local control that was resistant to endocrine therapy.
The median time from diagnosis to progression requiring change in treatment was 645 days (IQR, 250-908), and the average time to all-cause death was 938.5 days (IQR, 462-1403.5). A total of 68 women (72%) died, 3 from distant breast cancer metastases, at the time of the analysis.
“Primary endocrine therapy allows most women to avoid surgery without disease progression in the breast or symptomatic distant metastases,” the researchers concluded.
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Williams L, Lewis R, Law R, et al. Long term outcome of patients treated with primary endocrine therapy. Poster presented at: 17th St. Gallen International Breast Cancer Conference 2021; March 17-20, 2021. Abstract P132.