Multiple oral cancer development-Clinico-pathological features in the Hong Kong population

Background Multiple squamous cell carcinoma (SCC) development within the oral cavity is an important consequence of mucosal field cancerization. We have previously profiled contemporaneous demographics and confirmed a rising incidence of oral cancer within the Hong Kong population. In this further study, we sought to characterize the presenting clinico-pathological features and clinical outcome consequent upon multiple primary tumour (PT) development. Methods Having accessed the Hong Kong Hospital Authority (HA) database to identify new cases of oral SCC diagnosed during an 18-year period (November 1999 to October 2018), specific clinico-pathological data were retrieved for patients who developed multiple oral SCCs during the study period. Results Out of 6706 identified SCC cases, 769 patients (11.5%) developed multiple PTs, most commonly 2 (663) but 3 (91), 4 (12), 5 (2) and 6 (1) were also observed. The male to female ratio was 2.25 to 1 (P = .004), with female patients significantly older at first tumour presentation (P = .002), demonstrating longer periods before second PT development (P = .001) and better long-term survival than males (P = .001). Buccal mucosa (143), oropharynx (134) and tongue (112) were the sites most frequently affected by second tumours. Whilst buccal SCC showed a propensity for subsequent buccal tumour development (60), oropharynx primaries developed second PTs most frequently on the tonsil (28) and tongue (27). Tongue primaries were associated with second PTs on the floor of mouth (61) and oropharynx (57). Conclusion Development of multiple oral cancers is a significant risk in Hong Kong, particularly for male patients. Following initial tumour management, regular and careful patient follow-up is important for early recognition of multiple SCC development.