Oral cavity cancer incidence rates in Osaka, Japan between 2000 and 2014

We investigated trends in oral cavity cancer incidence from 2000 to 2014 in Osaka, Japan.

Using Osaka Cancer Registry (OCR) data, oral cavity cancer incidence number and age-standardized incidence rates were calculated according to three 5-year-time-periods: 2000-2004, 2005-2009 and 2010-2014. We calculated the distribution of clinical stage for each 5-year period and the proportion of oral cavity cancer among all cancers.

A total of 6,086 oral cavity cancers were registered in OCR in 2000-2014. Across the period, between 55.6% and 65.0% were 65 years+ and approximately 60% were men. Tongue cancer accounted for 30.4% to 43.8% of the registrations, while gum accounted for 30.7% to 34.7%. 36.3% to 37.3% were regional, while 1.8% to 2.8% were distant. The age-standardized incidence rate of oral cavity cancer increased from 2.1/100,000 in 2000 to 3.8/100,000 in 2014, although the proportion of oral cavity cancer among all cancers only increased slightly from 0.71% in 2000 to 0.92% in 2014. Proportion of localized stage cancer was 60.8%-67.5% for tongue and 31.0%-49.5% for gum or floor of mouth. Proportion of distant stage cancer was 0.3%-1.0% for tongue and 2.5%-4.2% for gum or floor of mouth.

Age-standardized incidence rate of oral cavity cancer increased, but was not higher than other countries. The proportion of localized stage tongue cancer was higher, while that of distant stage cancer was lower than other sites. Tongue cancer might be easier to detect in its earlier stages than other sites.