We sought to determine whether sequencing of treatment impacted outcomes in older, comorbid patients. Using the National Cancer Database(2010-2017), 2911 patients >
70 with a Charleson Deyo Comorbidity(CCDM) score of 2/3 and cT1c-3/N0-3/HER2 positive or triple-negative breast cancer treated with chemotherapy,surgery,or both were included. Chi-square tests evaluated differences between groups. Multivariable models evaluated associations between overall survival and treatment. Majority 87.4%(n = 2544) underwent surgery first and 36.0%(n = 917) received adjuvant chemotherapy while 77.9%(n = 286) of chemotherapy first patients underwent surgery. Receipt of both modalities was associated with the best survival followed by surgery alone then chemotherapy alone. Additional analysis demonstrated no survival difference between patients who underwent surgery(±systemic therapy) vs systemic therapy(±surgery) first. Although combined treatment offers the best survival, as a single modality, patients treated with surgery vs systemic therapy alone fare better. This information in conjunction with patient preferences on quality of life can be used in making shared decisions.