Exploring variations in ovarian cancer survival by age and stage (ICBP SurvMark-2): A population-based study.

OBJECTIVE: The study aims to evaluate the differences in ovarian cancer survival by age and stage at diagnosis within and across seven high-income countries. METHODS: We analyzed data from 58,161 women diagnosed with ovarian cancer during 2010-2014, followed until 31 December 2015, from 21 population-based cancer registries in Australia, Canada, Denmark, Ireland, New Zealand, Norway, and United Kingdom. Comparisons of 1-year and 3-year age- and stage-specific net survival (NS) between countries were performed using the period analysis approach. RESULTS: Minor variation in the stage distribution was observed between countries, with most women being diagnosed with 'distant' stage (ranging between 64% in Canada and 71% in Norway). The 3-year all-ages NS ranged from 45 to 57% with Australia (56%) and Norway (57%) demonstrating the highest survival. The proportion of women with 'distant' stage was highest for those aged 65-74 and 75-99 years and varied markedly between countries (range:72-80% and 77-87%, respectively). The oldest age group had the lowest 3-year age-specific survival (20-34%), and women aged 65-74 exhibited the widest variation across countries (3-year NS range: 40-60%). Differences in survival between countries were particularly stark for the oldest age group with 'distant' stage (3-year NS range: 12% in Ireland to 24% in Norway). CONCLUSIONS: International variations in ovarian cancer survival by stage exist with the largest differences observed in the oldest age group with advanced disease. This finding endorses further research investigating international differences in access to and quality of treatment, and prevalence of comorbid conditions particularly in older women with advanced disease.