A first look at relative survival by stage for colorectal and lung cancers in Canada.

J Chadder,R Dewar,J Niu,D Nishri,G Lockwood,L Shack

doi:10.3747/co.23.3096

Abstract

Monitoring and reporting on cancer survival provides a mechanism for understanding the effectiveness of Canada's cancer care system. Although 5-year relative survival for colorectal cancer and lung cancer has been previously reported, only recently has pan-Canadian relative survival by stage been analyzed using comprehensive registry data. This article presents a first look at 2-year relative survival by stage for colorectal and lung cancer across 9 provinces. As expected, 2-year age-standardized relative survival ratios (arsrs) for colorectal cancer and lung cancer were higher when the cancer was diagnosed at an earlier stage. The arsrs for stage i colorectal cancer ranged from 92.2% in Nova Scotia [95% confidence interval (ci): 88.6% to 95.1%] to 98.4% in British Columbia (95% ci: 96.2% to 99.3%); for stage iv, they ranged from 24.3% in Prince Edward Island (95% ci: 15.2% to 34.4%) to 38.8% in New Brunswick (95% ci: 33.3% to 44.2%). The arsrs for stage i lung cancer ranged from 66.5% in Prince Edward Island (95% ci: 54.5% to 76.5%) to 84.8% in Ontario (95% ci: 83.5% to 86.0%). By contrast, arsrs for stage iv lung cancer ranged from 7.6% in Manitoba (95% ci: 5.8% to 9.7%) to 13.2% in British Columbia (95% ci: 11.8% to 14.6%). The available stage data are too recent to allow for meaningful comparisons between provinces, but over time, analyzing relative survival by stage can provide further insight into the known differences in 5-year relative survival. As the data mature, they will enable an assessment of the extent to which interprovincial differences in relative survival are influenced by differences in stage distribution or treatment effectiveness (or both), permitting targeted measures to improve population health outcomes to be implemented.

Highlights

Colorectal cancer and lung cancer are two of the most common cancers affecting Canadians
Through the National Cancer Staging Initiative led by the Canadian Partnership Against Cancer, population-level staging data for colorectal cancer and lung cancer became available in 9 provinces starting in 20104
The arsrs for stage i colorectal cancer ranged from 92.2% in Nova Scotia (95% ci: 88.6% to 95.1%) to 98.4% in British Columbia (95% ci: 96.2% to 99.3%)

Summary

Introduction

Colorectal cancer and lung cancer are two of the most common cancers affecting Canadians. Pan-Canadian reporting of cancer outcomes, undertaken in collaboration with provincial and territorial partners, has focused on 5-year relative survival, which is important for monitoring the success of cancer control initiatives[3]. Those estimates fail to distinguish the degree to which differences in relative survival can be explained by early or late diagnosis rather than by variation in treatment practices. Relative survival for both colorectal and lung cancer varies across the country[2] and merits further exploration with respect to the underlying factors causing the differences. Because of the timing of staging data availability, the analysis of relative survival could include only the 2-year ratios

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Conclusion