Effect of age and gender in non-smokers with oral squamous cell carcinoma: Multi-institutional study.

BACKGROUND: In developing countries, oral squamous cell carcinoma (OSCC) is predominantly a cancer affecting older males who smoke tobacco. In countries with effective public health strategies, smoking rates are declining rapidly. It is not clear if patients who develop OSCC without these traditional risk factors represent a clinically distinct cohort with different prognosis. A recent analysis found that elderly non-smoking females with OSCC had significantly worse prognosis, concluding that this was a distinct patient population with poorer survival. The primary aim of this study was to determine the effect of gender and age on prognosis in OSCC, and the interaction between these two variables. METHODS: Multinational multi-institutional data were collected from six sites. The primary outcome of interest was disease specific survival (DSS). Time to local, regional, and distant recurrence were investigated as secondary outcomes. RESULTS: 3379 patients with OSCC were included. Males had significantly worse DSS compared to females (HR 1.24, 95% CI 1.08-1.43, p = 0.003). Females <70 years of age had significantly better DSS compared to females >/=70 years of age (HR 0.69, 95% CI 0.51-0.94, p < 0.001) but elderly females had similar DSS to males, regardless of age. When age was divided into three groups, the middle-aged group (45-69 years) had a significantly better DSS compared to elderly patients (HR 0.87, 95%CI 0.78-0.96, p < 0.001), however younger patients had similar DSS to elderly patients. When the effect of age (young v middle v elderly) was compared in each gender, young and middle-aged females had the most favourable DSS (log-rank p < 0.001). Middle-aged females who smoked had a 10% survival advantage compared to middle-aged males that smoked at five years. CONCLUSIONS: Age, gender, tumour subsite, and smoking status are important drivers of survival in OSCC. However, gender appears to be the most important predictor with young and middle-aged females having the most favourable prognosis.