The incidence and risk of second primary cancers in patients with nasopharyngeal carcinoma: a population-based study in Taiwan over a 25-year period (1979-2003)

Background: Very few reports are available on the incidence and risk of second primary cancers in nasopharyngeal carcinoma (NPC) cases, and most of these are single-institution reviews with relatively small case numbers and short follow-up. Patients and methods: A population-based study was conducted. We quantified standardized incidence ratios (SIRs) and cumulative incidence of second cancers among 23 639 individuals with initial diagnoses of NPC. Results: We found a 24% increased risk of second cancers in NPC patients compared with the general population [SIR = 1.24, 95% confidence interval 1.15-1.33]. Elevated SIRs were observed in the following second primary cancers: oral/pharyngeal, salivary gland, sarcoma, skin and leukemia/lymphoma. The cumulative incidence > 10 years was 3.26%. The risk was higher in younger patients, especially those < 40 years old. After diagnosis of second cancers, the median survival time was 1.7 years. Conclusions: This is the largest population-based study to date from a high-incidence area. We found that NPC is associated with an increased risk of second malignancies, which had a negative impact on the survival of patients who survived NPC.