Cannabis Use Shifted From Smoking to Pharmaceutical Products After Stem Cell Transplant | Research

The takeaway

Among 30 hematology patients undergoing stem cell transplant, cannabis use declined slightly (46% to 40%), but shifted from smoking toward pharmaceutical cannabinoid products and oils after transplant, with increased oncology provider engagement.

Hematologists, oncology providers, and cancer patients considering cannabis around transplant.

Provider-initiated cannabis conversations rose from 10% to 37%

What the researchers found

Cannabis use decreased from 46% to 40% after transplant. Smoking as primary method dropped (38% to 18% of users), while pharmaceutical cannabinoid use increased (13% to 21%). Provider-initiated cannabis conversations increased from 10% to 37% post-transplant. Of the total sample, 63% experienced post-treatment complications and 33% developed graft-versus-host disease, 6 of whom were recent cannabis users.

Why it matters

This is the first study of cannabis use specifically among stem cell transplant patients. The shift toward safer consumption methods and increased provider engagement suggests that the transplant experience prompts both patients and providers to reconsider cannabis use patterns.

The numbers in context

N = 30. Pre-HCT: 46% used cannabis, 38% smoked. Post-HCT: 40% used, 18% smoked. Pharmaceutical cannabinoids: 13% to 21%. Provider-initiated conversations: 10% to 37%. Complications: 63%. GVHD: 33% (6 of 10 were recent cannabis users).

How the study worked

Longitudinal survey study of 30 eligible hematology patients assessed before and 90 days after hematopoietic stem cell transplant. Surveys covered cannabis use rate, beliefs, access to information, and physical and psychological outcomes.

What this study cannot tell us

Very small sample (n=30). No control group. Cannot determine whether cannabis affected transplant outcomes. The GVHD observation is hypothesis-generating given the small numbers. Self-reported cannabis use.

How to read the evidence

Very small prospective cohort (n=30) providing descriptive data. Preliminary evidence for this specific population.

When this study was published

Published in 2025.

The bigger picture

Cancer patients undergoing intensive treatments like stem cell transplant face unique considerations for cannabis use, including immunosuppression and drug interactions. This study provides initial data to inform clinical guidance for this high-risk population.

Questions still open

Does cannabis use affect GVHD risk after stem cell transplant? Should transplant protocols include specific cannabis guidance?

Common questions

Is cannabis safe during stem cell transplant?

This small study cannot answer that definitively. Cannabis use shifted toward safer methods post-transplant, but 6 of 10 GVHD cases were recent cannabis users, raising questions that need larger studies to address.

Why did providers discuss cannabis more after transplant?

Provider-initiated conversations tripled post-transplant (10% to 37%), possibly because transplant teams are more attuned to medication interactions and infection risks, making cannabis use a more pressing clinical concern.

Read the original research

Cannabis in Hematology Survey Study (CHESS): A Longitudinal Investigation on Uses, Attitudes, and Outcomes of Cannabis Among Hematology Patients Undergoing Hematopoietic Stem Cell Transplant.

International journal of environmental research and public health, 22(7)

View on PubMed ↗Publisher’s paper ↗

Citation

McLennan, Andrew I G; Booker, Reanne; Roessner, Cameron; Kerba, Marc. (2025). Cannabis in Hematology Survey Study (CHESS): A Longitudinal Investigation on Uses, Attitudes, and Outcomes of Cannabis Among Hematology Patients Undergoing Hematopoietic Stem Cell Transplant.. International journal of environmental research and public health, 22(7). https://doi.org/10.3390/ijerph22070990