Incidence, trends, and survival of oropharyngeal squamous cell cancer in Aotearoa New Zealand, 2006-2020.

BACKGROUND: An increasing trend of oropharyngeal cancer (OPC) has been reported in several countries with different demographic characteristics, and often attributed to increases in human papillomavirus (HPV) infection. The survival of patients with OPC has steadily improved, especially for those with positive HPV status. This study assessed the incidence, trends, and survival of OPC in Aotearoa New Zealand (NZ) by age at diagnosis, sex and ethnicity. METHODS: The study included all 2109 patients resident in NZ with a primary diagnosis of oropharyngeal squamous cell carcinoma from 2006 to 2020, identified from the National Cancer Registry. We assessed age-standardised incidence rate (ASR), annual percent change (APC) and overall and relative survival rates. RESULTS: The average annual incidence of OPC was 2.2 per 100,000 population. There was a steady increase of 4.9% per year over 15 years. Although the incidence rates were higher in males over the study period, the overall rate of increase was similar in males (4.9%) and in females (4.3%). The incidence was highest in the 50-69-year group (8.8/100,000 population). This age group had an incidence that increased by 7.5% per year to 2018, and then declined. The main increase in rates was seen between the birth cohort of 1946-50 and that of 1956-60. The increase in incidence was seen in Maori and Pakeha/European populations, but no increase was seen in Pacific or Asian populations. The 5-year overall relative survival rate improved from 69% in 2006-13 to 78% in 2014-20. Survival rates were lower in older patients, females, and Maori patients. CONCLUSION: This study confirmed a substantial increase in OPC incidence in NZ, with some evidence to suggest a recent slowing in this increase. Maori and Pakeha/European had the highest incidence, while Pacific and Asian populations showed the lowest rates and no increase over the study period. Survival rates have improved over time, but remained lower in some demographic groups.

The risk of subsequent invasive melanoma after a primary in situ or invasive melanoma in a high incidence country (New Zealand).

Background: Patients with invasive melanoma are at increased risk of developing subsequent invasive melanoma, but the risks for those with primary in situ melanoma are unclear. Objectives: To assess and compare the cumulative risk of subsequent invasive melanoma after primary invasive or in situ melanoma. To estimate the standardized incidence ratio (SIR) of subsequent invasive melanoma compared to population incidence in both cohorts. Methods: Patients with a first diagnosis of melanoma (invasive or in situ) between 2001 and 2017 were identified from the New Zealand national cancer registry, and any subsequent invasive melanoma during follow-up to the end of 2017 identified. Cumulative risk of subsequent invasive melanoma was estimated by Kaplan-Meier analysis separately for primary invasive and in situ cohorts. Risk of subsequent invasive melanoma was assessed using Cox proportional hazard models. SIR was assessed, allowing for age, sex, ethnicity, year of diagnosis and follow up time. Results: Among 33 284 primary invasive and 27 978 primary in situ melanoma patients, median follow up time was 5.5 and 5.7 years, respectively. A subsequent invasive melanoma developed in 1777 (5%) of the invasive and 1469 (5%) of the in situ cohort, with the same median interval (2.5 years) from initial to first subsequent lesion in both cohorts. The cumulative incidence of subsequent invasive melanoma at 5 years was similar in the two cohorts (invasive 4.2%, in situ 3.8%); the cumulative incidence increased linearly over time in both cohorts. The risk of subsequent invasive melanoma was marginally higher for primary invasive compared to in situ melanoma after adjustment for age, sex, ethnicity and body site of the initial lesion (hazard ratio 1.11, 95% CI 1.02-1.21). Compared to population incidence, the SIR of invasive melanoma was 4.6 (95% CI 4.3-4.9) for the primary invasive and 4 (95% CI 3.7-4.2) for the primary in situ melanoma cohorts. Conclusions: The risk of subsequent invasive melanoma is similar whether patients present with in situ or invasive melanoma. Thus follow-up surveillance for new lesions should be similar, although patients with invasive melanoma require more surveillance for recurrence.