A prospective observational study to assess the epidemiological profile of multiple primary cancers in Eastern India

ABSTRACT Background: Multiple primary cancers once thought to be rare have become increasingly common as the lifespan of cancer survivors has increased with availability of better and more effective cancer treatment. However, their exact incidence is not known and data on their epidemiological characteristics are not available. Aim: The aim of this study is to study the epidemiologic characteristics of multiple primary cancers in the eastern region of India. Materials and Method: The study was conducted in the Department of Surgical Oncology, Medical College, Kolkata, from 2017 to 2020 over a period of 3 years. All patients with a diagnosis of second primary as per International Agency for Research on Cancer (IARC) definition or those developing a second primary within the study period were included for analysis. Data were recorded in form of preformed questionnaires. All the cases were followed up for at least 12 months. Result: Fifty cases of multiple primary tumors were identified, out of which 21 were synchronous while rest 29 were metachronous type. The male–female ratio was 1:1.2. The median age at presentation for index malignancy was 50 years. The most common malignancy in the synchronous group was a combination of variety of GI cancers (six cases). In the metachronous category, a combination of reproductive cancers (breast, ovary, cervix, and endometrium) along with Gastrointestinal cancer (GI) cancers (colon, rectum) was most frequently found (eight cases). Definite risk factors for multiple primary tumors were identifiable in 10 cases: arsenic exposure in 5 cases, hereditary in 4 cases, and immunosuppression in 1, while in 8 cases, risk factors were only speculative (radiation 5 cases, chemotherapy 3). At the time of the last follow-up, 36 subjects were alive and 3 dead while the status of 11 subjects was unknown. Conclusion: This is the first comprehensive study on multiple primary cancers and the largest so far in India. Our study overcomes the shortcoming of previous case series from our subcontinent. The merits of our study include the use of the most accepted IARC definition, updated staging guidelines with long follow-up, and reliable survival data. Additionally, we could identify risk factors in 50% of our subjects. And our study shows various new combinations of cancers not reported before. Clustering of cases in the young adolescent group (25–49) years is also a new finding. We also highlight the existing ambiguity in the way this entity is defined. Demerits include the loss of follow-up data in a significant number of patients.