44P - Pathological complete response to neoadjuvant chemotherapy and outcomes in Her-2 negative locally advanced breast cancer

Background

Management of Her-2 negative breast cancer is evolving. Literature on response and outcomes to neoadjuvant chemotherapy (NACT) is limited from the Indian subcontinent. In this study, we evaluated the pathological complete response(pCR) rates to NACT, and outcomes in Her2-negative breast cancers, which includes TNBC and hormone receptor-positive (HR+) cohorts.

Methods

Her2-negative breast cancer patients who received neoadjuvant chemotherapy and then underwent surgery between January 2017 and December 2021 at a tertiary cancer hospital in India were included. Pathological response to chemotherapy, and outcomes were noted by retrospective electronic medical record review. pCR was defined as complete disappearance of all invasive carcinoma cells in the breast and axillary lymph nodes (ypT0/ypN0).

Results

Of the 1760 Her-2 negative breast cancers who were registered at our institute in the above time period, 232 patients received NACT, and 172 patients who completed NACT and then underwent surgery were included in the analysis. The median age of presentation was 50 years (Range 31-74 years). The median age was 46 years in the TNBC cohort, and 55 years in HR+ cohort. Majority of the patients received anthracycline/taxane based chemotherapy, and 94.1% (162/172) of the patients received all planned cycles of chemotherapy before surgery. Overall pathological complete response (pCR) was seen in 27.3% of patients (47/175). pCR rates were significantly higher in the TNBC cohort compared to HR+ cohort (38.2% vs 15.6 %, P - 0.001). TNBC variant and higher histologic grade (Grade III) were associated with significantly higher pCR rates. At a median follow-up of 30.8 months, 23.2% of patients (40/172) developed relapse (26.9% in TNBC, 19.2 % in HR+). Patients who achieved pCR had significantly lower chances of recurrence compared to those with non-pCR to chemotherapy (12.7% vs 27.2%, P- 0.045).

Conclusions

Triple-negative breast cancer subtype and higher histologic grade are associated with significantly higher pathological complete response to NACT. Achieving complete pathological response is associated with lower risk of breast cancer recurrence, and it is an important surrogate marker for recurrence-free and overall survival.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.