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.