OBJECTIVES: Upon disease progression or early termination of a trial, cancer patients in the control arm of clinical studies commonly switch to the experimental drug or receive other post-study treatments. The objective of this study was to assess the willingness of HTA agencies to accept the statistical methods that are available to adjust overall survival (OS) estimates for resulting bias. METHODS: PubMed and the ADIS R&D Insights database were searched to identify pivotal trials involving treatment switching. Related HTA appraisals, published between January 2011 and February 2014, were then selected from the HTA agencies websites for further analysis. Reports from 10 agencies were considered for review. RESULTS: Sixteen pivotal trials and 45 related HTA appraisals were selected for in-depth analysis. It was widely acknowledged by all HTA agencies that treatment switching could confound the OS estimates when an inferior drug is used as a comparator. Our analysis suggests that statistical adjustment methods are discussed more often and more thoroughly by agencies that base their decisions on cost-effectiveness outcomes. On one end, NICE accepts and reviews the selection and implementation of such methods in detail, and has recently developed its own guidelines on the appropriate handling of treatment switching. Various examples have been identified and accepted in SMC and PBAC submissions. TLV, ZiNL, pCODR and INESSS have accepted statistical adjustments in at least one case. No evidence of such adjustments was identified in the selected HAS reports. On the other end, recent case examples among IQWiG submissions suggest that they do not accept the use of these methods. CONCLUSIONS: The rationale to adjust for treatment switching and the methods used need to be justified towards agencies accepting the correction techniques. Other payers will rather want to base their decision on results of the last “unbiased” dataset.