Cancer incidence and survival for 11 cancers in the Commonwealth: a simulation-based modelling study.

Background: The number of new cancer cases in Commonwealth countries rose by 35% between 2008 and 2018, but progress in cancer control has been slow in many low-income and lower-middle-income member states. We aimed to examine cancer outcomes and priority areas in the Commonwealth to provide insight and guidance on prioritisation of efforts to improve cancer survival and make the best use of scarce resources.

Methods: We adapted a previously developed microsimulation model of global cancer survival for 11 cancer sites (oesophagus, stomach, colon, rectum, anus, liver, pancreas, lung, breast, cervix uteri, and prostate). All 56 Commonwealth countries were included and classified based on the 2020 World Bank Income groups (low-income, lower-middle-income, upper-middle-income, and high-income countries) and Commonwealth geographical areas. We modelled the number of incident cancer cases in each Commonwealth country in 2020, based on age group-specific estimates of incidence rates from GLOBOCAN 2020. We simulated 5-year net survival for each patient, accounting for the stage at diagnosis (I-IV), availability of specific treatment and imaging modalities, and quality of care (based on residual differences in expected versus observed survival after accounting for the availability and effectiveness of treatment and imaging modalities). We also simulated counterfactual policy scenarios, in which we scaled up various aspects of cancer care to the mean level of high-income countries to estimate the comparative effectiveness of different policies.

Findings: Incident cancers in the Commonwealth accounted for an estimated 14·3% of global diagnosed cancer cases in 2020 among the 11 cancers modelled (1 610 000 Commonwealth cases [95% UI 1 556 000-1 674 000] of 11 227 000 global cases [11 069 000-11 406 000]) and are estimated to increase to 17·3% in 2050 due to population growth (3 330 000 [3 154 000-3 539 000] of 19 308 000 [18 706 000-19 911 000]). The 5-year net survival across 11 cancers combined in 2020 was 30·7% (95% UI 22·4-38·6) in Commonwealth countries, ranging from 4·1% (0·04-15·2) in low-income countries, 17·8% (3·7-30·9) in lower-middle-income countries, 33·1% (23·7-46·0) in upper-middle-income countries, to 59·0% (57·8-60·2) in high-income countries. Among single treatment policies, scaling up access to radiotherapy had the largest survival impact in low-income countries, surgery had the largest impact in lower-middle-income and upper-middle-income countries, and targeted therapy had the largest impact in high-income countries. By geographical area, improving radiotherapy availability was estimated to have the largest impact in Africa, surgery in Asia, targeted therapy in the Caribbean and the Americas and Europe, and quality of care in the Pacific Commonwealth countries. Comparing packages of scaling up the availability of all treatment modalities versus imaging modalities, expanding availability of imaging yielded the largest benefits in high-income countries, and in the Caribbean and the Americas, Europe, and the Pacific, whereas expanding treatment yielded larger benefits in all other income groups and geographical areas.

Interpretation: We found large variation in 5-year net survival, with a nearly 15-times difference in cancer survival by country income group within the Commonwealth. Efforts to improve the availability of treatment and imaging modalities and quality of care will be crucial to reduce these disparities, with specific priorities of scale-up policies varying by setting. The Commonwealth could leverage a broad range of knowledge and resources and have an important role in supporting member countries with setting-specific priorities to improve cancer outcomes.

Funding: Harvard T H Chan School of Public Health.