A review found cannabis has not been proven to cause lung cancer but evidence remains limited | Research

The takeaway

A review in the Journal of Thoracic Oncology concluded that smoking cannabis has not been proven to increase lung cancer risk, while noting emerging evidence for cannabis as an adjunct in cancer symptom management, particularly for chemotherapy-induced nausea and pain.

Oncologists fielding patient questions about cannabis; cannabis researchers; patients with cancer considering cannabis for symptom management.

Smoking cannabis has not been proven to be a lung cancer risk factor

What the researchers found

Researchers reviewed the evidence on cannabis, lung cancer risk, and therapeutic applications in oncology.

On lung cancer risk: smoking cannabis has not been proven to be a risk factor for lung cancer development. However, the authors noted that existing studies are limited by small sample sizes, self-reporting errors, few heavy cannabis-only smokers in study populations, and confounding from concurrent tobacco use.

On therapeutic use: increasing evidence supports cannabis for managing chemotherapy-induced nausea and vomiting (CINV) and cancer-related pain. However, studies are limited by difficulties in standardizing doses and accurately measuring the biological activity of different cannabis compounds.

The authors called for controlled trials with standardized CBD and THC dosing to better establish both safety and therapeutic potential.

Why it matters

With cannabis use rising and cancer patients increasingly asking about it, this review from a major oncology journal provides a balanced assessment. The finding that cannabis smoking has not been proven to cause lung cancer is notable, though the authors are careful to emphasize the limitations of existing evidence rather than declaring it safe.

The numbers in context

Millions of regular cannabis users worldwide were referenced. No specific risk ratios for lung cancer were established due to insufficient data quality.

How the study worked

Narrative review of clinical and preclinical literature on cannabis, lung cancer, and cancer symptom management. Published in the Journal of Thoracic Oncology.

What this study cannot tell us

Narrative review rather than systematic review or meta-analysis. Limited by the quality of underlying studies. The lung cancer safety question remains open rather than resolved.

How to read the evidence

Moderate. Published in a top oncology journal with balanced assessment, but limited by the quality of underlying primary studies.

When this study was published

Published in 2018. Cannabis-cancer research has continued, though large definitive trials remain scarce.

The bigger picture

This review sits at the intersection of two important questions: whether cannabis use carries cancer risk, and whether it has therapeutic value for cancer patients. The honest answer to both is that better studies are needed, particularly randomized controlled trials with standardized dosing.

Questions still open

Would large, well-controlled prospective studies of heavy cannabis-only smokers reveal a lung cancer risk? What standardized cannabis formulations work best for CINV and cancer pain?

Common questions

Does this mean smoking cannabis is safe for the lungs?

Not exactly. The review found that cannabis smoking has not been proven to cause lung cancer, but the evidence is limited. Cannabis smoke contains many of the same carcinogens as tobacco smoke, and the absence of proof of harm is not the same as proof of safety.

Can cannabis treat cancer itself?

This review focused on symptom management (nausea, pain), not cancer treatment. While some preclinical research has explored anti-tumor effects of cannabinoids, this review did not make claims about cannabis treating cancer directly.

Read the original research

Cannabis Use, Lung Cancer, and Related Issues.

Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer, 13(4), 480-487

View on PubMed ↗Publisher’s paper ↗

Citation

Jett, James; Stone, Emily; Warren, Graham; Cummings, K Michael. (2018). Cannabis Use, Lung Cancer, and Related Issues.. Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer, 13(4), 480-487. https://doi.org/10.1016/j.jtho.2017.12.013