Management and Outcomes of Merkel Cell Carcinoma in Canada Between 2000 and 2018 from the Pan-Canadian Merkel Cell Collaborative.

BACKGROUND

The management and survival outcomes of patients with Merkel cell carcinoma (MCC) in Canada are currently unknown. The objective of this study was to investigate the management and outcomes of patients diagnosed with MCC in Canada from 2000 to 2018.

PATIENTS AND METHODS

This retrospective cohort study evaluates management and temporal survival differences among patients diagnosed with MCC in ten large urban university centers in three provinces during three periods: 2000-2005, 2006-2011, and 2012-2018.

RESULTS

There were 899 patients included with a median follow-up of 22.8 months. There were no significant changes in patient and tumor characteristics between the three periods. There were increases in the use of radiologic staging (2000-2005, 53.4%; 2006-2011, 73.7%; 2012-2018, 78.1%; p < 0.01), surgery as the sole treatment (2000-2005, 25.7%; 2006-2011, 34.0%; 2012-2018, 31.8%; p = 0.02), and surgery with adjuvant radiation (2000-2005, 37.2%; 2006-2011, 36.2%; 2012-2018, 43.7%; p =0.02) during the study period. Between 2000 and 2018, the 5-year median overall survival (OS) was 47.9% (95% confidence interval (CI) 43.2-55.8%), disease-free survival was (DFS) 48.9% (95% CI 42.4-55.1%), and cancer-specific survival (CSS) was 49.7% (95% CI 43.2-55.8%). There were no significant differences in OS and DFS between the three periods on multivariable analysis. Compared with 2000-2005, there was no significant difference in CSS from 2006 to 2011 (hazard ratio (HR) 1.02 95% CI 0.66-1.62, p = 0.9), but there was a significant improvement in CSS from 2012 to 2018 (HR 0.57 95% CI 0.34-0.97, p = 0.04).

CONCLUSIONS

Despite changes in the utilization of staging, surgery, and radiation, the prognosis of patients with MCC in Canada remains poor, highlighting the need for improved management strategies.