Cannabis Smoking Was Linked to Higher Risk of Nasopharyngeal Cancer in North Africa | Research

The takeaway

Marijuana smoking significantly elevated nasopharyngeal carcinoma risk independently of cigarette smoking in a large North African case-control study, suggesting different cancer-causing mechanisms between cannabis and tobacco.

Read this if you smoke cannabis and want to understand respiratory cancer risks beyond tobacco.

Cannabis independently elevated NPC risk in 1,251 participants across three countries

What the researchers found

Researchers interviewed 636 nasopharyngeal carcinoma (NPC) patients and 615 matched controls across Algeria, Morocco, and Tunisia.

Cigarette smoking and snuff were associated with differentiated NPC but not with undifferentiated carcinoma (UCNT), the dominant type in these populations.

Marijuana smoking significantly elevated NPC risk independently of cigarette smoking. Statistical analyses (stratified permutation test and conditional logistic regression) confirmed this was an independent effect, suggesting cannabis and tobacco may cause cancer through different mechanisms.

Domestic cooking fumes from charcoal ovens during childhood also increased risk. Neither alcohol nor water pipe smoking was associated with NPC.

Why it matters

This was one of the first studies to identify cannabis as an independent risk factor for a specific cancer type in a large population, separate from tobacco effects.

The numbers in context

636 NPC patients and 615 controls from Algeria, Morocco, and Tunisia. Cannabis effect was independent of cigarette smoking. Childhood cooking fume exposure (from charcoal ovens) also elevated risk.

How the study worked

This case-control study enrolled 636 NPC patients and 615 controls from three North African countries (2002-2005), frequency-matched by center, age, sex, and childhood household type. Conditional logistic regression evaluated lifestyle associations with NPC risk, controlling for socioeconomic status and dietary factors.

What this study cannot tell us

Case-control design relies on participants accurately recalling past cannabis use. North African cannabis use patterns (kif smoking) may differ from patterns in other regions. NPC is a relatively uncommon cancer with specific regional risk factors that may not apply broadly.

How to read the evidence

Large multi-country case-control study with appropriate matching and statistical controls, though retrospective design introduces recall bias.

When this study was published

Published in 2009. The relationship between cannabis smoking and head/neck cancers has continued to be studied with mixed results in different populations.

The bigger picture

The cancer risks of cannabis smoke remain debated. This study provided population-level evidence for one specific cancer type, though nasopharyngeal carcinoma is relatively rare and has unique risk factors including Epstein-Barr virus exposure.

Questions still open

What specific compounds in cannabis smoke contribute to NPC risk? Does the independent effect suggest a different carcinogenic pathway than tobacco? Would these findings apply to non-smoked cannabis products?

Common questions

Does cannabis cause cancer?

This study found cannabis smoking was associated with one specific cancer type (nasopharyngeal carcinoma) in North Africa. It does not establish that cannabis causes cancer broadly, but it does suggest combusted cannabis may carry independent cancer risks for certain tissues.

Is the risk from smoking specifically, or from cannabis itself?

The study examined smoked cannabis. The carcinogenic risk likely comes from combustion products rather than cannabinoids themselves, which is why route of administration matters for risk assessment.

Read the original research

Cannabis, tobacco and domestic fumes intake are associated with nasopharyngeal carcinoma in North Africa.

British journal of cancer, 101(7), 1207-12

View on PubMed ↗Publisher’s paper ↗

Citation

Feng, B-J; Khyatti, M; Ben-Ayoub, W; Dahmoul, S; Ayad, M; Maachi, F; Bedadra, W; Abdoun, M; Mesli, S; Bakkali, H; Jalbout, M; Hamdi-Cherif, M; Boualga, K; Bouaouina, N; Chouchane, L; Benider, A; Ben-Ayed, F; Goldgar, D E; Corbex, M. (2009). Cannabis, tobacco and domestic fumes intake are associated with nasopharyngeal carcinoma in North Africa.. British journal of cancer, 101(7), 1207-12. https://doi.org/10.1038/sj.bjc.6605281