A long-term retrospective observational study at a medium-sized medical oncology service in Switzerland: comparison of overall survival with a national cohort and adherence to treatment guidelines

AIMS: There is a lack of national and international publicly available long-term survival outcome data from individual healthcare providers in medical oncology. In this study, the overall survival at a medium-sized medical oncology service at Olten Cantonal Hospital was evaluated and compared as a local benchmark report with national data from the Swiss Cancer Registries. Furthermore, adherence to treatment guidelines was investigated as an additional quality indicator. METHODS: The 1- and 5-year overall survival of all patients with breast cancer, testicular cancer, colon cancer, non-small-cell lung cancer, Hodgkin lymphoma, and diffuse large B-cell lymphoma in Switzerland from 2008 to 2017 with at least one outpatient visit at the in-house medical oncology service at Olten Cantonal Hospital was analysed and compared with the specific overall population-based outcome data provided by the National Agency for Cancer Registration (NACR), which were set as a national benchmark. Until 2020, no data from the Canton of Solothurn, to which Olten belongs, were reported to the NACR. Further, adherence to internationally recognized clinical guidelines for stage-specific treatment was assessed. RESULTS: Until September 8, 2020, data on 842 patients with a median follow-up period of 70 months were collected and analysed. The 1- and 5-year overall survival for colon and non-small cell cancer, Hodgkin lymphoma, and diffuse large B-cell lymphoma and the 5-year overall survival for testicular cancer in the Olten cohort did not significantly differ from the NACR data. The 1-year overall survival for testicular cancer was not comparable statistically. The 5-year overall survival for breast cancer (unadjusted for stage) was significantly higher in the NACR collective (84.5%) than in the Olten collective (79.7%) but not for the individual breast cancer stages. The Olten collective included approximately 2.5 times as many patients with stage 4 breast cancer (17.5%) as the NACR collective (6.9%). Approximately 92.4% of the patients in the curative setting and 85.8% of the patients in the palliative setting received first-line treatment according to guidelines. CONCLUSIONS: The statistically comparable local 1- and 5-year overall survival of the analysed malignancies, with adjustment for stage for the 5-year overall survival for breast cancer, is in line with the national benchmark. Adherence to treatment guidelines is high.