Degree of Cancer Spread at Presentation and Survival Among Adolescents and Young Adults in New South Wales, Australia

Purpose: Five-year relative cancer survival increased from 80% to 89% among adolescent and young adult (AYA) Australians between 1985-1989 and 2011-2015. New South Wales (NSW), with a third of the Australian population, has long recorded degree of spread (localized, regional, or distant) at diagnosis. This study complements national data by investigating survival increases after adjusting for differences in degree of spread, cancer type, and sociodemographic characteristics. Methods: Population-based NSW Cancer Registry data, for malignant solid cancers where degree of spread was applicable, were analyzed for ages 15-24 years in 1980-2015. Subhazard ratios (SHRs) from competing risk regression indicated risk of death from the primary cancer as opposed to other causes. Multiple logistic regression was used to model odds ratios for more extensive compared with localized spread at diagnosis. Results: Approximately 72% of cancers had a localized degree of spread. Adjusted SHRs for cancer-specific mortality decreased from 1980-1989 to 2010-2015 (SHR: 0.73, 95% confidence interval: 0.55-0.95). Adjusted odds ratios (aORs) for more advanced versus localized spread were lowest for melanoma and lip, oral cavity, and pharyngeal carcinoma, and highest for breast carcinoma, Ewing tumor, and colorectal carcinoma. The aOR for more advanced versus localized cancer was higher for men than women. Conclusions: Cancer survival increased to a statistically significantly in AYAs during 1980-2015, after adjusting for degree of spread, cancer type, and sociodemographic characteristics. We attribute this mostly to treatment gains. Linked data should be used to explore treatment contributions.