The emergence of oral cavity cancer and the stabilization of oropharyngeal cancer: Recent contrasting epidemics in the South Korean population.

BACKGROUND: By analyzing the recent epidemiologic trajectory of head and neck squamous cell carcinoma (HNSCC) in South Korea, we tracked 2 findings that have been reported recently in other countries: the stabilization of human papillomavirus (HPV)-related HNSCC incidence and the acceleration of oral cavity cancer incidence. METHODS: We analyzed data from the comprehensive population-based Korean Central Cancer Registry for the period 1999 to 2017. The age-standardized incidence rate (ASR), annual percent change (APC), and relative survival were calculated. RESULTS: The ASR of total HNSCC decreased from 1999 to 2017 (APC, -0.2 [95% CI, -0.3 to -0.0]), as did the ASR of HPV-unrelated HNSCC (APC, -0.6 [95% CI, -0.8 to -0.5]); however, the ASR of HPV-related HNSCC increased (APC, 2.9 [95% CI, 2.5 to 3.2]). The rapidly increasing incidence of tonsil squamous cell carcinoma, which was the main subsite of HPV-related HNSCC, stabilized after 2011 (APC pre-2011, 6.8 [95% CI, 5.0 to 8.3]; APC post-2011, 1.6 [95% CI, -2.1 to 5.5]), and the difference was significant (P = .017). In contrast, oral cavity cancer incidence demonstrated the only increase among HPV-unrelated subsites, with the increase occurring after 2006 (APC pre-2006, 1.6 [95% CI, 0.3 to 2.8]; APC post-2006, 2.8 [95% CI, 2.2 to 3.5]); the main cause of this change was an increase in the ASR of tongue cancer. CONCLUSION: This study demonstrates the recent stabilization of tonsil cancer incidence and the contrasting increase in oral cavity cancer incidence, unlike other HPV-unrelated cancers. These trends require further surveillance and understanding in terms of tumor biology and prevention.