Incidence, timing, presentation, treatment, and outcomes of second primary head and neck squamous cell carcinoma after oral cancer

After their initial presentation of oral squamous cell carcinoma (SCC), patients have a lifelong risk of developing another new SCC of the head and neck. The aim of this study was to establish second primary rates, baseline characteristics (site, clinical or pathological stage, and smoking and alcohol history), timing, presentation, treatment, and outcomes. From the regional unit we analysed records of patients treated with curative intent for their first oral cancer between 2002 and 2007 inclusive. All patients had had at least 10 years of follow up either to death or the end of 2017. A total of 347 patients had been treated with curative intent, and of them, 29 had a second primary at a median (IQR) of 52 (30-79) months after the index operation. The incidence of developing a second primary tumour within two years was 1.7% (95% CI: 0.7% to 3.7%), within five years was 4.9% (95% CI: 2.9% to 7.7%), and within 10 years was 7.8% (95% CI: 5.1% to 11.1%). Early stage of first cancer was the only significant factor (p = 0.001) for development of a second primary within 10 years, reflecting survivorship. Most second primaries (21 patients) were staged as early, and by visual inspection. Most (n = 20) were within the oral cavity, one of which overlapped the oropharynx; eight others were in the oropharynx, and one in the larynx. Most patients (n = 22) were treated by operation with curative intent. Three were treated palliatively. Patients need to be aware of the risk of a second primary and, as most are in the mouth or oropharynx, there is a role for surveillance by primary dental care practitioners.