Abstract
Oral cavity squamous cell carcinoma (OSCC) accounts for over 90% of oral cancer. It is typically diagnosed at an advanced stage with subsequent poor prognosis for survival and other outcomes. Inconsistencies in OSCC classification, distinct from other head and neck cancers, have restricted an understanding of its epidemiology, trends over time and staging profile in Aotearoa New Zealand. Patients with OSCC can be referred from primary care by both general practitioners and dentists. International evidence suggests that patients whose OSCC was detected by dentists are more likely to be diagnosed at an early stage resulting in better outcomes. Given differences in delivery and accessibility of oral health care, it is not known if the same applies in Aotearoa New Zealand, where over half of the adult population cannot access regular dental care, and Māori, Pacific peoples, and those on low incomes experience the most significant barriers
This study aimed to update the epidemiology and staging profile of OSCC in Aotearoa New Zealand from 2010 to 2019, investigate OSCC presentations to primary care, and examine how the initial detection source influences disease stage and outcomes.
Two studies were conducted. The first was a population-based descriptive epidemiological analysis of New Zealand Cancer Registry data for OSCC cases diagnosed between 2010 to 2019, identified using appropriate ICD-O-3 morphologic and site codes. Across period average age-standardised incidence rates were calculated, overall and stratified based on ethnicity, gender, and socioeconomic deprivation. The second study was a cross-sectional analysis based on a retrospective notes review of patients (sampled from the population-based analysis, with weightings applied to make the results representative of the wider set of patients) to describe the diagnostic pathways patients with OSCC followed and how the referral source relates to stage at diagnosis.
Of 1780 cases of OSCC diagnosed and reported to the New Zealand Cancer Registry during the study period, an average across period age-standardised rate of 2.7 per 100,000 (95% CI, 2.6 – 2.8) was found. Greatest burden of disease was observed in Pacific peoples and those living in deprived areas. Based on the 344 sampled individuals, 58.6% of people with OSCC were diagnosed at an advanced stage (AJCC stage III +), disproportionately higher among Māori, Pacific peoples, and those in deprived areas. The majority of cases (61.8%) were detected by general practitioners, and those diagnosed through this pathway
were 3.5 times more likely than cases identified by dental practitioners to be diagnosed at an advanced stage (95% CI 2.3 – 5.2). Those with the greatest burden of advanced- stage disease that is, Māori, Pacific and the most deprived, were least likely to have their cancer detected by a dentist.
These findings provide evidence for the urgent need to prioritise OSCC and oral health at all levels. Key recommendations include raising public awareness of OSCC, integrating oral health education into medical and non-oral health professional programs, and recognising poor dental attendance as a risk factor for advanced stage OSCC to inform improved access to equitable access to oral health care.