Off-label drug use in oncology practice: a nationwide cross-sectional survey among Turkish medical oncologists.

BACKGROUND

Off-label drug use is a common but understudied phenomenon in oncology. The extent to which oncologists are aware of the regulatory status of the drugs they prescribe remains unclear. This study aimed to assess knowledge, attitudes, barriers, and self-reported practices regarding off-label drug use among medical oncologists in Türkiye, and to evaluate the discrepancy between actual prescribing behavior and awareness of off-label status.

METHODS

A cross-sectional, web-based survey was conducted among medical oncologists across Türkiye between October 2025 and February 2026. The questionnaire comprised 37 items covering demographics, knowledge and perceptions, decision-making resources, barriers, informed consent practices, self-reported off-label rates, and 15 clinical scenarios representing drug–indication pairings that are all off-label per the Turkish regulatory authority (TİTCK). Descriptive statistics, chi-square tests, Mann-Whitney U tests, and Kruskal-Wallis tests were used for analysis.

RESULTS

A total of 192 oncologists from 41 cities participated (mean age 42.9 ± 9.1 years; 52.6% senior faculty). While 92.2% reported being at least familiar with off-label use, only 35.4% rated themselves as highly knowledgeable. The most frequently used off-label drugs were gemcitabine in cholangiocarcinoma (99.5% regular use), carboplatin in endometrial cancer (97.3%), and oxaliplatin in pancreatic cancer (96.8%). The primary barrier was reimbursement issues (90.1%). Critically, when asked to estimate how many of the 15 presented scenarios were off-label (all 15 are), only 5.2% correctly identified all as off-label, and 43.8% estimated that only 1–5 were off-label. No significant differences were observed by seniority level, experience, or patient volume.

CONCLUSIONS

Off-label drug use is highly prevalent in Turkish oncology practice, yet oncologists substantially underestimate the extent of off-label prescribing. This awareness gap has significant implications for informed consent, medicolegal liability, and regulatory policy. Educational interventions and clearer regulatory frameworks are needed to bridge this gap. TRIAL REGISTRATION: Not applicable.