Risk for a second primary hypopharyngeal and esophageal cancer after an initial primary oral cancer

Objective: To investigate the risk for second primary cancer in the hypopharynx and esophagus (SPC-HE) among individuals with an initial oral/oropharyngeal cancer. Materials and Methods: Mass screening data from Taiwan (2004–2009) included individuals who were ≥18 years old and smoked cigarettes and/or chewed betel quid. Occurrence of SPC-HE was monitored until December 31, 2014. Results were expressed as adjusted relative risk (aRR) and 95% confidence interval (CI). Results: One hundred and fifty-eight out of 4,494 subjects with oral cancer developed SPC-HE (incidence rate: 6.47 per 1,000 person-years). Relative to patients with primary cancers in the lip, the risk of an SPC-HE was higher in patients with primary cancers in oropharynx (aRR: 19.98, 95% CI: 4.72–84.55), floor of mouth (aRR: 12.13, 95% CI: 2.67–55.15), and hard palate (aRR: 7.31, 95% CI: 1.65–32.37), but not in patients with cancers in tongue (aRR: 3.67, 95% CI: 0.89–15.17) or gum (aRR: 3.99, 95% CI: 0.92–17.35). Regression analyses also showed the risk of an SPC-HE was greater in alcohol drinkers than those who did not (aRR: 1.65, 95% CI: 1.10–2.48). Conclusions: Compared with the initial cancer in the lip, patients with a cancer in the oropharynx, floor of mouth, and hard palate had a higher risk for the SPC-HE.