Abstract Purpose Medicines in special situations (MSS) refer to off‐label or to unlicensed drugs under investigation (compassionate use). Our objectives were to evaluate characteristics and to estimate overall survival (OS), event‐free survival (EFS), and the duration of treatment (DT) of MSS used for cancer treatment at a multicentre comprehensive cancer institution. Methods Retrospective cohort study on adult cancer patients for whom an MSS treatment was requested (January 2011–December 2020). A descriptive analysis was performed and median OS and EFS and 95% confidence intervals (CIs) were estimated. Survival curves were stratified by type of tumor, ECOG (Eastern Cooperative Oncology Group) performance status (PS), age, sex, treatment stage and type of drug (mechanism of action and target). Results Treatment was initiated in 2092 episodes (1930 patients) out of 2377 MSS episodes (2189 patients) requested, 33% for hematological treatment and 87% for advanced stage cancer. Median OS (months) was 21.1 (95% CI 19.4–22.7), median EFS was 5.6 (95% CI 5.1–6.0) months, and median DT was 4.5 [0.0; 115.3] months. OS and EFS statistically significantly favored female patients, ECOG PS ≥2 episodes showed worse OS and EFS outcomes (p