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Axillary pathologic complete response linked to longer survival in breast cancer
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Axillary pathologic complete response appeared associated with improved 10-year RFS and OS in patients with breast cancer who had cytologically confirmed axillary lymph node metastases, according to the results of a retrospective study.
Patients with HER-2–positive breast cancer treated with targeted therapies appeared to achieve axillary pathologic complete response at a significantly high rate, results showed.
“Over the past several years, more data have emerged regarding the rates of pathologic complete response in the breast and axilla in different breast cancer subtypes after primary systemic chemotherapy with different chemotherapy backbones,” Vicente Valero, MD, FACP, professor and deputy chairman of the department of breast medical oncology at The University of Texas MD Anderson Cancer Center, and colleagues wrote. “Previous studies have shown that pathologic complete response in the axillary nodes has a greater effect on survival than the response to chemotherapy in the primary breast tumor.”
Valero and colleagues sought to determine the long-term effect of axillary pathologic complete response on RFS and OS in women with breast cancer who had confirmed axillary lymph node metastases who underwent treatment with primary systemic chemotherapy.
They retrospectively reviewed medical records of women diagnosed with stage II to stage III breast cancer with axillary lymph node metastases. All study participants received primary systemic chemotherapy between 1987 and 2007 at MD Anderson Cancer Center.
Researchers stratified women by axillary status after primary systemic chemotherapy and estimated survival outcomes according to response in the breast and axilla.
OS and RFS served as primary endpoints.
The analysis included data from 1,600 women (median age at diagnosis, 49 years; range, 21-86), of whom 454 (28.4%) achieved axillary pathologic complete response.
Women who achieved axillary pathologic complete response appeared more likely to have HER-2–positive or triple-negative breast cancer (P < .001), pathologic complete response in the breast (P < .001), high-grade tumors (P < .001), and lower clinical and pathologic T stage (P = .002).
Compared with patients who had residual axillary disease, patients with axillary pathologic complete response appeared more likely to achieve 10-year OS (84% vs. 57%; P < .001) and RFS (79% vs. 50%; P < .001).
Among patients with axillary pathologic complete response, 10-year OS was higher among those with pathologic complete response in the breast (90% vs. 72%; P < .001).
Among patients with residual axillary disease, those who achieved pathologic complete response in the breast achieved better 10-year OS (66% vs. 56%; P = .02).
Approximately 67% (n = 100) of 149 patients with HER-2–positive disease who received HER-2 targeted therapy achieved axillary pathologic complete response. Among this subset, patients who achieved pathologic complete response had better 10-year OS (92% vs. 57%; P = .003) and RFS (89% vs. 44%; P < .001).
Monica Morrow
The researchers identified limitations to their study. Due to the retrospective, single-center design, the findings may not be widely generalizable. Further, they noted that missing data regarding hormone receptor and HER-2 status may have influenced outcomes.
“Molecular-based correlates in future protocols may enhance our understanding of the biologic differences between the primary tumor in the breast and axillary lymph node metastases,” Valero and colleagues wrote. “Further studies are needed to determine whether patients with residual disease after primary systemic chemotherapy, particularly in the axillary lymph nodes, may benefit from further therapy after surgery to reduce the risk for relapse and improve survival.”
Neoadjuvant chemotherapy may be the key to more complete response among women with breast cancer, leading to better outcomes, Monica Morrow, MD, chief of the breast service in the department of surgery at Memorial Sloan Kettering Cancer Center, wrote in an accompanying editorial.
“Recognition of the poorer survival outcomes of those who do not achieve pathologic complete response with neoadjuvant therapy, particularly in the setting of triple-negative breast cancer, has led to a new generation of clinical trials examining the use of additional chemotherapy, immunotherapy and anti–HER-2 therapy in this setting,” Morrow wrote. “Conversely, the high rates of RFS in patients having pathologic complete response in the study of Mougalian and colleagues support the premise being tested in the ongoing NGR 9353 trial that patients presenting with nodal metastases who have a nodal pathologic complete response after neoadjuvant therapy may not require nodal field irradiation or postmastectomy chest wall irradiation. Positive results in any of these studies would provide compelling evidence that neoadjuvant therapy allows more precise tailoring of treatment and should be the standard of care for operable breast cancer.” – by Cameron Kelsall
Disclosure: The researchers and Morrow report no relevant financial disclosures.
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