Time-trends and age and stage differences in 5-year relative survival for common cancer types by sex in the canton of Zurich, Switzerland

BACKGROUND Survival trends help to evaluate the progress made to reduce the burden of cancer. The aim was to estimate the trends in 5-year relative survival of patients diagnosed with breast, prostate, lung, colorectal cancer and skin melanoma in the time periods 1980-1989, 1990-1999, 2000-2009 and 2010-2015 in the Canton of Zurich, Switzerland. Furthermore, we investigated relative survival differences by TNM stage and age group. METHODS Data from the Cancer Registry of Zurich was used from 1980 to and including 2015, including incident cases of breast (N = 26,060), prostate (N= 23,858), colorectal (N= 19,305), lung cancer (N= 16,858) and skin melanoma (N= 9780) with follow-up until 31 December 2020. The cohort approach was used to estimate 5-year relative survival. RESULTS The 5-year relative survival increased significantly between 1980 and 1989, and 2010 and2015: from 0.70 to 0.89 for breast, from 0.60 to 0.92 for prostate, from 0.09 to 0.23 (men) and from 0.10 to 0.27 (women) for lung, from 0.46 to 0.66 (men) and from 0.48 to 0.68 (women) for colorectal cancer, and from 0.74 to 0.94 (men) and from 0.86 to 0.96 (women) for skin melanoma. Survival for stage IV tumors was considerably lower compared to lower-staged tumors for all cancer types. Furthermore, relative survival was similar for the age groups <80 years but lower for patients aged 80 years and older. CONCLUSION The observed increasing trends in survival are encouraging and likely reflect raised awareness around cancer, improved diagnostic methods, and improved treatments. The fact that stage I tumor patients have generally high relative survival reflects the efforts made regarding early detection.