Clinical features and treatment outcomes of Japanese head and neck cancer patients with a second primary cancer.

Aim It has been well established that patients with head and neck cancer (HNC) have an elevated risk of developing a second primary cancer (SPC), owing to the common carcinogenic risk factors, including tobacco and alcohol consumption, and inactive aldehyde dehydrogenase-2 genotype. Here we investigated the current state of SPC in Japanese HNC patients. Methods We retrospectively investigated the incidence and treatment outcomes of synchronous and metachronous SPCs among 434 newly diagnosed HNC patients. Moreover, the associations between various carcinogenic risk factors and SPC were also assessed. Results Fifty-two (12.0%) and 104 patients (24.0%) had synchronous and metachronous SPCs, respectively. The cases with SPC were associated with high rates of smoking and alcohol histories (81.1% and 74.6%, respectively). Immunohistochemical analysis revealed that 47.5% of all oropharyngeal cancer cases showed positive p16 expression, and there was no significant difference between p16-positive and -negative cases in terms of the proportions of patients with SPC. The 3-year overall survival rates were 78.8%, 75.3% and 75.9% in patients without, with synchronous, and with metachronous SPC, respectively ( P = 0.4048). Conclusion Given the distinct features of the carcinogenic risk factors for HNC in Japan, care should be taken not to underestimate the frequency of SPC, even for human papillomavirus-related oropharyngeal cancer patients. Considering the high incidence of SPC associated with HNC, the appropriate diagnostic strategy to allow for early detection of SPC and a treatment strategy aimed at avoiding unnecessary radiotherapy for the index tumor would contribute to improving the prognosis for HNC. [ABSTRACT FROM AUTHOR]