CHICAGO—For premenopausal breast cancer patients, 24 weeks of neoadjuvant chemotherapy may yield a better clinical response than endocrine therapy, according to a new study.
Neoadjuvant endocrine therapy has been shown to be effective in hormone-responsive postmenopausal breast cancer patients. “We aimed to assess the efficacy and safety of cytotoxic chemotherapy versus endocrine therapy for hormone-responsive, lymph node-positive, premenopausal breast cancer patients in a neoadjuvant setting,” said Hee Jeong Kim, MD, of the department of surgery at the University of Ulsan College of Medicine, Asan Medical Center, in Seoul, South Korea, at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting, held June 2–6 in Chicago (abstract 517).
In this phase III, randomized, double-blind, parallel group, multicenter study, 187 premenopausal women with estrogen receptor–positive, HER2-negative, and lymph node–positive premenopausal breast cancer patients were randomized to either 24 weeks of neoadjuvant chemotherapy with doxorubicin plus cyclophosphamide every 3 weeks for 4 cycles followed by a taxane every 3 weeks for 4 cycles, or neoadjuvant endocrine therapy with goserelin 3.6 mg every 4 weeks with a daily 20 mg dose of tamoxifen.
The researchers randomly assigned the patients to chemotherapy (95 patients, median age 42.5 years) or endocrine therapy (92 patients, median age 41.5 years); 174 patients completed the 24-week neoadjuvant treatment period, 87 patients in each group.
Slightly less than half (48%) of the patients in the chemotherapy arm planned to have a mastectomy and slightly more than half (52%) were planning breast-conserving surgery. In the endocrine therapy arm, almost two-thirds (61%) of the patients planned a mastectomy and more than one-third (39%) were scheduled for breast-conserving surgery.
More patients in the chemotherapy group had a complete response or partial response (83.9%) than did those in endocrine therapy arm on caliper (71.3%) and on MRI (chemotherapy 83.7% vs endocrine therapy 52.9%).
Three patients in the chemotherapy group (3.4%) and 1 patient (1.15%) in the endocrine treatment group showed complete pathologic response, Kim noted.
In the patients who had breast cancer with low Ki 67 expression (less than 20%) on initial biopsy, clinical responses on caliper were similar in both treatment arms (hazard ratio, 0.958).
Five patients who had no tumors on the breast or in lymph nodes after 24 weeks of neoadjuvant endocrine therapy had higher estrogen receptor scores. Four of the 5 patients had low grade (grade 1 or 2), low Ki 67 (20% or less) expression on the initial biopsy specimen.
In conclusion, Kim said: “Neoadjuvant chemotherapy showed better clinical response than neoadjuvant endocrine therapy in hormone receptor–positive, HER2-negative premenopausal breast cancer over 24 weeks. Even in lymph node–positive breast cancer, endocrine therapy can be effective in low Ki 67 hormone-responsive breast cancer.”
ASCO discussant Harold Burstein, MD, associate professor of medicine at Harvard Medical School in Boston, said, “The goal of neoadjuvant therapy is to change the surgical options. If patients need neoadjuvant therapy, then the question becomes do they need chemotherapy? If they don’t need chemotherapy and need an approved surgical option, then endocrine therapy has robust data to suggest it can be effective.”
He cautioned clinicians to anticipate planning for the management of eventual residual disease.