Abstract Multiple primary malignancies (MPMs) are increasingly being detected with improved survival and diagnostics. However, Indian data remain limited. This study evaluated the epidemiology of MPMs in a tertiary cancer center. To analyze the clinicopathological profile, survival outcomes, and etiological factors of patients with MPMs at a South Indian cancer center. This is a retrospective observational study of patients with MPMs analyzed between March 2023 and July 2025. Patients were identified using the Warren–Gates criteria. Data on demographics, tumor sites, histology, stage, treatment, and outcomes were collected. The overall survival (OS) was estimated using the Kaplan–Meier method. Sixty-five patients were included: 37 metachronous (56.9%), 27 synchronous (41.5%), and 1 triple primary (1.5%). The median age at diagnosis was 54 years for synchronous malignancy, while for metachronous cases, index cases are usually diagnosed at a median age 48 years and second primary cancer diagnosed on a median age of 51 years, with a median interval of 20 months. Male more common for synchronous, while female common in metachronous. Breast cancer was most common among metachronous index and second primary cases, and gastrointestinal tumors were predominant among synchronous cases, and adenocarcinoma was the most common histology. Molecular testing was performed whenever feasible. Index metachronous tumors were mostly nonmetastatic (86.5%), whereas second primaries metastatic (40.5%) burden was increased. Treatment completion was highest for first primaries (89%), followed by second (43%) and synchronous tumors (56%). The etiological links were mainly tobacco-related (45%) and genetic (35%). Median OS was 86.0 months for metachronous, 29.0 months for synchronous, and 10.0 months for triple primaries; overall cohort median OS was 43.0 months. MPMs in this Indian cohort showed distinct patterns of breast and gastrointestinal predominance, limited molecular testing, and a survival advantage for metachronous disease. These findings support long-term surveillance, tobacco-control measures, and integration of genetic counselling and molecular profiling in low- and middle-income country settings.
AH et al. (Wed,) studied this question.