Long-term outcomes of neoadjuvant treatment in older patients with HER2-positive breast cancer: Evidence from a single center in Mexico.

Andrea Maliachi Diaz Instituto Nacional de Cancerología, Mexico City, DF, Mexico info_outline Andrea Maliachi Diaz, Alexandra Garcilazo Reyes, Carlos Arturo González Núñez, Areli Velazquez Martinez, Diana Fabiola Flores Diaz, Jose Rodrigo Espinosa Fernandez, Alberto Alvarado Miranda, Claudia Arce-Salinas, Paula Anel Cabrera-Galeana

Authors Andrea Maliachi Diaz Instituto Nacional de Cancerología, Mexico City, DF, Mexico info_outline Andrea Maliachi Diaz, Alexandra Garcilazo Reyes, Carlos Arturo González Núñez, Areli Velazquez Martinez, Diana Fabiola Flores Diaz, Jose Rodrigo Espinosa Fernandez, Alberto Alvarado Miranda, Claudia Arce-Salinas, Paula Anel Cabrera-Galeana Organizations Instituto Nacional de Cancerología, Mexico City, DF, Mexico Abstract Disclosures Research Funding No funding sources reported Background: The optimal approach to managing breast cancer (BC) in elderly women is still far from certain. These patients are often underrepresented in clinical trials, leaving the long-term effectiveness and safety aspects of treatment unclear. This study aimed to assess long-term survival outcomes of neoadjuvant treatment and cardiac toxicity in geriatric HER2-positive BC patients. Methods: Patients aged over 64, diagnosed with clinical stage IIA-IIIC HER2-positive BC between January 2007 and December 2022, were retrospectively reviewed. Patients were identified from Instituto Nacional de Cancerologia's Breast Cancer Unit database. Only those receiving neoadjuvant treatment were selected. Treatment information: left ventricular ejection fraction (LVEF) measurements and survival events were captured from medical electronic records. Descriptive statistics were used to report patient characteristics and treatment details. Event-free survival (EFS) and Overall Survival (OS) were evaluated with Kaplan-Meier. Cardiac toxicity was defined as a decrease in LVEF >10% over baseline or <50% during neoadjuvant therapy, and was compared between anthracycline-based and anthracycline-free regimens. Results: A total of 193 patients with an age greater than 64 and clinical stage IIA-IIIC HER2-Positive BC were identified from a database of 10.859 BC patients. From these, 87 patients received neoadjuvant treatment. As documented comorbidities prior to initiation of treatment, 54.0% of patients reported hypertension, 18.4% had diabetes, 81.6% were found with overweight or obesity, 12.6% were smokers, and 3.4% had a history of cardiovascular disease. The median age was 68, the median number of administered cycles was 8, and 88.5% of patients underwent surgery. The median follow-up was 9.25 years. Median EFS was 12.3 years, median OS was unreached, EFS-3yr was 76.3% and OS-3yr was 88.1%. Among patients who underwent surgery, 48.0% and 66.7% achieved a complete pathological response (ypT0/is ypN0) when treated with anthracycline-based and anthracycline-free regimes, respectively. The proportion of patients who developed cardiac toxicity during neoadjuvant treatment was 14.7%, all treated with anthracycline-based regimens. One patient under an anthracycline-based regime developed clinical heart failure. No cardiac toxicity was observed in patients treated with anthracycline-free regimens. Conclusions: Our findings show that, in this complex older population, long-term survival outcomes do not appear low. In addition, anthracycline-free regimens might represent a safer alternative from a cardiovascular perspective. Despite limitations of retrospective studies, this research addresses a long-standing gap in the representation of geriatric patients in clinical trials and contributes as a basis for improving neoadjuvant strategies.