Breast pCR, Nodal Status Can Predict Nodal pCR for Specific Cancer Subtypes Treated With Chemotherapy

Breast pathological complete response (pCR) and pre-treatment nodal status were found to be predictive of nodal pCR for patients with breast cancer treated with neoadjuvant chemotherapy, according to data from the CALGB 40601 (NCT00770809) and CALGB 40603 (NCT00861705) trials presented at the Society of Surgical Oncology 2021 International Conference on Surgical Cancer Care.

More than 95% of patients who have a clinical nodal status (cN) of 0 and experience breast pCR also experienced nodal pCR, according to the study’s conclusions.

“Downstaging axillary nodal disease with neoadjuvant chemotherapy provides an opportunity to potentially de-escalate axillary surgery,” explained study author Anna Weiss, MD, of the Brigham and Women’s Hospital, in her presentation of the data. “Current surgical procedures and imaging modalities may lack sensitivity to accurately predict modal pathologic complete response.”

The CALGB 40601 trial examined patients with HER2-positive breast cancer treated with paclitaxel plus trastuzumab (Herceptin) with or without lapatinib (Tykerb). In the CALGB 40603 trial, patients with triple-negative breast cancer were treated with paclitaxel plus carboplatin, bevacizumab (Avastin) or both, followed by dose-dense doxorubicin and cyclophosphamide.

In total, the analysis included 760 patients with stage II to III HER2-positive or triple-negative breast cancer. Of that population, patients who underwent axillary surgery before neoadjuvant chemotherapy (n = 122), patients with missing pre-treatment cN (n = 58), and patients with missing pathologic node-negative status (n = 41) were excluded from the study population. A total of 539 patients remained eligible for analysis in the study.

In regard to the results, the overall nodal pCR rate for the total population was 76.3%. Specifically, when broken down by cN category, the nodal pCR rate was 88.8% for patients with cN0, 66.2% for patients with cN1, and 65.6% for patients with cN2 or cN3 (P < 0.0001).

More, when analyzing nodal pCR by in-breast response, patients who experienced a breast pCR (48.8% of patients) saw a nodal pCR of 93.2%, while patients with breast residual disease (51.2% of patients) saw a nodal pCR of 60.1% (P < 0.0001).

Weiss broke down the specifics of the nodal pCR rates for the cohort of patients who experienced a breast pCR, finding that 96.3% of patients with cN0 had pathologic node-negative status. Among patients with cN1 and cN2 or cN3, that rate was 91.7% and 88.2%, respectively.

For the breast residual disease group, the patients with cN0 had pathologic node-negative status of 82.7%, while the patients in the cN1 and cN2 or cN3 cohorts had rates of 39.7% and 37%, respectively. For both the breast pCR and breast residual disease cohorts, there was no statistically significant difference in nodal pCR by tumor subtype.

Weiss concluded the results section of her presentation by noting that patients with breast and nodal residual disease had worse overall survival rates while patients with nodal pCR and breast pCR had the best overall survival rates at a median follow-up of 103 months.

“These findings support the incorporation of axillary surgery de-escalation strategies in neoadjuvant chemotherapy trials,” Weiss concluded.

Reference:

Weiss A, Campbell J, Ballman KV, et al. Factors Associated with Residual Nodal Disease Among Breast Cancer Patients Treated with Neoadjuvant Chemotherapy: Results of CALGB 40601 (HER2+) and 40603 (triple-negative) (Alliance). Presented at: Society of Surgical Oncology 2021 International Conference on Surgical Cancer Care. Virtual. Abstract 12.