PurposeProper breast cancer screening and treatment should be considered in the elderly population; however, some tend to be less proactive. Our study aimed to investigate the impact of old age on treatment and prognosis in triple-negative breast cancer (TNBC). MethodThe study included patients with primary TNBC stage I-III diagnosed from 2002 to 2019 in single institution and retrospectively analyzed. We defined young (< 40 years), middle and old (> 70 years) groups. Clinicopathological factors, treatment, and prognosis were analyzed according to age group of TNBC patients. ResultTNBC patients aged 70 and above were 3.3 times more likely (P = .019) to have lymph node metastasis at the time of diagnosis compared to younger patients, but were found to be 0.24 times less likely to receive chemotherapy. (P = .003) Old TNBC patients have an expected likelihood 2.2 times higher of undergoing mastectomy rather than breast-conserving surgery. (P = .042) The 5-year prognosis is poorer in young and old group. (61%, 86%, and 65% in young, middle, and old groups). (P < .001). In subanalysis, old group of stages I and II received fewer chemotherapy compared to youngers (P < .05), but not in stage III. In Cox regression analysis, age and stage had significant impact on prognosis (hazard ratio 2-3), but treatment factors did not. However, in stratified analysis of adjuvant therapy and stage, prognosis of Old TNBC patients in stage II was improved when they underwent neo or adjuvant chemotherapy. ConclusionTNBC presents challenges in older patients, who receive less aggressive treatment and have poorer outcomes. The primary cause of poor prognosis in old TNBC patients is the high disease stage at diagnosis, underscoring the need for promotion and education on early screening. Additionally, it is suggested that a more proactive approach to adjuvant chemotherapy is necessary for stage II old TNBC patients.