Incidence, Trends and Survival of Oral Cavity Squamous Cell Carcinoma in Aotearoa New Zealand over 15 Years (2006–2020)

Win Myint, Thu Thu; McIvor, Nick; Douglas, Richard; Cavadino, Alana; Elwood, Mark

doi:10.31557/APJCP.2025.26.6.2015

Incidence, Trends and Survival of Oral Cavity Squamous Cell Carcinoma in Aotearoa New Zealand over 15 Years (2006–2020)

Document Type : Research Articles

Authors

¹ Department of Epidemiology and Biostatistics, School of Population Health, The University of Auckland, Auckland, New Zealand.

² Department of Surgery, School of Medicine, The University of Auckland, Auckland, New Zealand.

³ Department of Otorhinolaryngology Head and Neck Surgery, Te Toka Tumai, Auckland, Te Whatu Ora, Health New Zealand.

10.31557/APJCP.2025.26.6.2015

Abstract

Background: Over recent decades, there have been changes in the incidence of squamous cell carcinoma of the oral cavity (OCSCC) in many countries. However, recent data on OCSCC in New Zealand has not been examined. This study examines the current incidence, trends and survival of OCSCC in New Zealand and identifies demographic differences by age, sex and ethnicity. Method: Patients with a primary diagnosis of OCSCC between 2006 and 2020 were retrieved from the National Cancer Registry. Age-standardised incidence rates (ASRs) were calculated and compared using age-standardised incidence rate ratios (ASRRs). Time trends were assessed by joinpoint regression with annual percentage changes, and overall and relative survival rates were estimated. Results: Over 15 years, 2094 cases of OCSCC were identified, and the average annual incidence was 2.1 per 100,000. The rates were higher in males (ASRR= 1.4 compared to females), older age groups (ASRR=11.3 in 50-69 years; ASRR=25.4 in 70+ years compared to <50 years), and Pasifika (ASRR=1.4, compared to European). OCSCC incidence increased significantly between 2009 and 2017 and decreased between 2017 and 2020. Females followed the same pattern of trends as overall OCSCC, while trends in males showed no significant changes. The survival outcome of OCSCC at five years was 57% and 66% for absolute and relative survival, respectively. Survival outcomes were poorer in males (HR = 1.20 compared to females), older age groups (HR=1.77 in 50-69 years; HR=4.21 in 70+ years compared to <50 years), Māori (HR=1.37 compared to European) and tumours originated from the floor of mouth (HR=1.40), palate (HR=1.47) and buccal (HR=1.54) compared to tongue. Conclusion: This study shows that the incidence of OCSCC overall and in females increased from 2009 to 2017, but declined significantly after 2017 in New Zealand. Incidence and survival rates are influenced by sex, age, ethnicity and subsite.

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