A retrospective (N=140) and a prospective (N=102) observational Israeli study by Bar-Sela and colleagues about cannabis potentially adversely impacting the response to immunotherapy have together been cited 191 times including by clinical practice guidelines. There have also been re-ports on PubPeer outlining unverifiable information in their statistics and numerous discrepan-cies calculating percentages. This report attempted to replicate the data-analysis including non-parametric statistics. Table 1 of the corrected prospective report contained 22 p-values but only one (4.5%) could be verified, despite the authors being transparent about the N and statistics employed. Cannabis users were significantly (p < .0025) younger than non-users but this was not reported in the retrospective report. There were also errors in percentage calculations (e.g. 13/34 reported as 22.0% instead of 38.2%). Overall, these observational investigations, and especially the prospective, appear to contain gross inaccuracies which could impact the statistical decisions (i.e. significant findings reported as non-significant or vice-versa). Although it is mechanistically plausible that cannabis could have immunosuppressive effects which inhibit the response to immunotherapy, these two reports should be viewed cautiously. Larger prospective studies of this purported drug interaction that account for potential confounds (e.g. greater nicotine smok-ing among cannabis users) may be warranted.