M. Vasigh1, D.M. Euhus1, F. Johnston1, O.A. Sogunro1 1The Johns Hopkins University School Of Medicine, Surgical Oncology, Baltimore, MD, USA
Introduction: Neoadjuvant chemotherapy (NAC) can increase the possibility of breast-conserving surgery (BCS) and downstage the axilla in clinically node-positive patients. The benefit of NAC in resectable, clinically node-negative breast tumors is in question. However, if chemotherapy is indicated in these patients, NAC can provide information regarding pathologic response to treatment, which has the potential to alter recommendations for adjuvant systemic and radiation therapy. In this uncertainty, we sought to examine national trends in NAC utilization among early-stage breast cancer patients who received chemotherapy.
Methods: We performed a retrospective analysis of the National Cancer Database (NCDB). We identified cN0, cT1-2, M0, stage I, and II female breast cancers who had primary site surgery and received chemotherapy between 2010-2021. Patients with a history of another malignancy, an unknown final pathology report, or a history of neoadjuvant radiotherapy or endocrine therapy were excluded. A pathologic complete response (PCR) was defined as having no residue of the primary tumor (ypT0) and no axillary residue (ypN0). Patients were categorized into four phenotypes: 1- hormone receptor-positive (HR+) and HER2+ as triple positive (TP); 2- HR+, HER2- as HR+; 3- HR-negative (HR-) and HER2+ as HER2+; and 4- HR-, HER2- as triple negative (TN). The trend of NAC utilization and PCR was evaluated within the entire cohort. A subgroup analysis by the phenotype was performed.
Results: A total of 295,110 cases were selected. The mean age of the patients was 56.6±12.0 years, and 64.2% of the cases were stage one. Invasive ductal carcinoma (IDC) constituted 83.6%, and 41.5% underwent mastectomy. NAC was administered in 38,315 (13%) patients, and 35.6% had a PCR. NAC patients were more likely to be TN (60.7% to 22.8%), HER2+ (11.7% to 6.3%), and stage II (68.4% to 31.0%) compared to the adjuvant chemotherapy (AC) group (p<0.001). Use of NAC increased from 5.5% in 2010 to 22.1% in 2021. When stratified by phenotype, NAC use increased in TN breast cancers from 10.9% to 46.1%, in HER2+ from 8.5% to 33.8%, in HR+ from 3.2% to 6.5%, and in triple positives from 3.6% to 28.4% (p<0.001 in all phenotypes). The highest rate of PCR was achieved in HER2+(48.7%), followed by TN breast cancers (39.2%). PCR could also be observed in 27.2% of the TP and 19.0% of the HR+ cancers. The PCR rate increased from 16.2% in 2010 to 45.6% in 2021. This trend could be observed in all phenotypes. (Figure 1)
Conclusion: The NAC utilization and the PCR rate have increased between 2010 and 2021 in stage I and II breast cancers. Although these results are promising, NAC should be administered selectively in early-stage breast cancers.