Dual primary malignancies in Kashmir: A five-year analysis of temporal patterns, gender-specific presentations and treatment outcomes in a high gastrointestinal cancer risk population.

Patients diagnosed with cancer remain at risk of developing subsequent primary malignancies due to genetic predisposition, environmental factors, and improved survival associated with advances in diagnosis and treatment. Understanding the pattern of dual primary malignancies is essential, yet evidence from low-resource regions such as Kashmir is scarce. This retrospective study analyses the frequency, clinical patterns, and histopathological profiles of second primary malignancies (SPMs) among patients treated at a tertiary cancer centre in northern India. Medical records of 5,731 patients seen at the Department of Radiation Oncology, Government Medical College, Srinagar, between January 2020 and December 2024 were reviewed using Warren and Gates criteria. Thirty-five patients were identified with SPMs, yielding an incidence of 0.611%. Of these, 60% were synchronous and 40% metachronous, occurring 10 months to 19 years after the first tumour. The median age at initial diagnosis was 58 years, with peak incidence in the sixth and seventh decades. Males predominated overall, although females were more likely to present with synchronous cancers, while males formed the majority of metachronous cases. Gastrointestinal cancers were the most common primary tumours, followed by breast and genitourinary malignancies, and this distribution was largely mirrored in secondary cancers. Notably, over 80% of patients had at least one gastrointestinal tumour, and more than half of breast cancer patients developed thyroid cancer as the second primary. Most patients received curative treatment for both malignancies. The findings highlight the need for sustained clinical vigilance and long-term follow-up to enable early detection and optimal management of SPMs.