Trends in incidence and survival from anal cancer and incidence of high-grade anal intraepithelial neoplasia in Denmark

OBJECTIVE: The aim of the current study was to assess temporal trends in incidence of anal squamous cell carcinomas (SCC) and high-grade anal intraepithelial lesions (AIN2/3), and estimate survival from anal cancer and factors related to 5-year mortality in Denmark.

METHODS: We analyzed anal SCC and AIN2/3 cases in the period of 1998-2018 from the Danish Cancer Register and the Danish Registry of Pathology, respectively. Overall, period, gender, and histology specific age-standardized incidence rates, average annual percentage change (AAPC), and 5-year relative survival were estimated. Cox proportional hazards models were applied to evaluate the effect on 5-year mortality of period, age, gender, and stage of disease.

RESULTS: Altogether 2580 anal cancers and 871 AIN2/3 were identified. The AIN2/3 incidence increased for women 1998-2007 (AAPC: 3.5% (95% CI -0.7, 8.0)) and then tended to decrease during 2008-2018(AAPC: -5.2% (95% CI -9.6, -0.6)). A similar pattern was observed for men, although at a lower incidence with the decrease starting later (2008-2012) and the trend not reaching statistical significance. The anal SCC incidence increased over the whole study period for both women and men (women AAPC: 4.0% (95% CI 3.2%, 4.9%) and men AAPC: 3.6% (95% CI 2.3%, 4.9%)). The relative survival improved over time (from 61% to 72%). Being older and male was associated with a higher risk of dying within 5 years.

CONCLUSIONS: There is a need to focus attention on anal cancer and its precursor lesions, as the cancer incidence continues to increase. Actions could include screening and gender-neutral HPV vaccination.