Deciphering the Patterns of Dual Primary Cases Registered at the Hospital-Based Cancer Registry: First Experience from Rural Cancer Center in North India.

 The objective is to present the patterns of dual primary malignancies diagnosed at the Pathology Laboratory of Cancer Hospital with the support from hospital-based cancer registry (HBCR), Sangrur, Punjab, India for the years 2018 and 2019.  HBCR abstracts data from electronic medical records. Trained cancer registry staff abstracts cases in standard pro forma. Dual primary was coded as per the International Agency for Research on Cancer rule and was rechecked by the pathologist.  Data about multiple primary was entered and documented in an Excel sheet. Time interval was calculated by subtracting the date of diagnosis for second primary and first primary.  A total of 6,933 cases were registered, 45 cases are dual primary (26 females, 19 males) of which 64.4% are synchronous and 35.6% metachronous cases. Seventy-nine percent received cancer-directed treatment for synchronous and 87% for metachronous. The most common sites of the primary tumor were breast (33%), head and neck (22.2%), gynecological sites (11%), prostate (9%), esophagus (4%), and remaining other tumors (20.8%). Most common sites for second malignancies were gastrointestinal (GI) tract (31%), gynecological sites (18%), head and neck (16%), hematological malignancies (7%), soft tissue sarcoma (4%), breast (2%), and other sites (22%).  More than 70% of cases of primary tumors were in breast, head and neck, gynecological, and prostate. Of these, more than 60% of the second malignancy was found in the GI tract, gynecological, and head and neck sites. Around two-thirds of dual tumors are synchronous. Breast cancer cases have higher incidence of second malignancy. Regular follow-up is necessary to assess the survival of the second primary.