Fourteen-year trends and disease burden of oral cancer in Dibrugarh, Assam (2005–2018): a retrospective registry-based study with indian standard population-standardized estimates

Abstract

Dibrugarh, a predominantly rural district in Upper Assam, has been identified as a high-burden area for oral cancer, possibly because of its distinct exposure patterns and limited access to screening and care. To characterize this burden, the present study assessed the epidemiology and temporal trends of oral cancer in Dibrugarh from 2005 to 2018. This study employed a retrospective, population-based design, including all histologically confirmed cases of malignant oral cancer in the Dibrugarh PBCR from 2005 to 2018. Patient identification and classification adhered to the NCDIR–ICMR guidelines, with malignancies coded according to ICD/ICD-O criteria (oral cavity: C00–C06). Intercensal population figures were estimated through exponential interpolation, whereas postcensus projections applied a ratio-based approach. Three rate measures were computed and standardized against the Indian reference population: age-specific incidence rates (ASIRs), crude rates (CRs), and age-adjusted rates (AARs). To examine temporal patterns, joinpoint regression was applied, yielding both the annual percent change (APC) and the average annual percent change (AAPC). A total of 1,237 cases were recorded (783 rural, 454 urban), with 73.2% ( n = 905) males. The median age at diagnosis ranged from approximately 50–60 years (rural females 53 years; urban females 57 years; rural males 55 years; urban males 59 years). The incidence was concentrated in the 40–64-year age group, with peak ASIRs observed among older males (e.g., urban males aged 65–69 years: 372.53 per 100,000 in 2007). The male CR declined from 13.9 per 100,000 people in 2005 to 12.4 per 100,000 people in 2018 (–10.8%), whereas the female CR increased from 4.8 to 5.7 per 100,000 people (+ 18.8%). Although urban AARs remained higher in absolute terms, rural AARs increased substantially (males: +19.4%; females: +67.4%), whereas urban AARs declined. Joinpoint analysis revealed significant increases among rural males (CR AAPC = 1.67%, p = 0.028; AAR AAPC = 1.24%, p = 0.043), whereas trends among females were not statistically significant. Squamous cell carcinoma (NOS) (40.74%) was the predominant histology, and radiotherapy (50.57%) was the most frequently recorded treatment. Oral cancer in Dibrugarh patients has a persistent male predominance, a higher incidence in urban areas, and a progressive shift toward increasing rural burden, which pivots region-specific prevention, screening, and referral strategies in rural populations.