JAMA Netw Open. 2019 Nov 01;2(11):e1916318. doi: 10.1001/jamanetworkopen.2019.16318.
Association Between Marijuana Use and Risk of Cancer: A Systematic Review and Meta-analysis.
JAMA network open
Mehrnaz Ghasemiesfe, Brooke Barrow, Samuel Leonard, Salomeh Keyhani, Deborah Korenstein
Affiliations
Affiliations
- Northern California Institute of Research and Education, San Francisco.
- San Francisco Veterans Affairs Medical Center, San Francisco, California.
- Currently a medical student at Warren Alpert Medical School of Brown University, Providence, Rhode Island.
- Department of Medicine, University of California, San Francisco.
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York.
- Weill Cornell Medical College, New York, New York.
PMID: 31774524
PMCID: PMC6902836 DOI: 10.1001/jamanetworkopen.2019.16318
Abstract
IMPORTANCE: Marijuana use is common and growing in the United States amid a trend toward legalization. Exposure to tobacco smoke is a well-described preventable cause of many cancers; the association of marijuana use with the development of cancer is not clear.
OBJECTIVE: To assess the association of marijuana use with cancer development.
DATA SOURCES: A search of PubMed, Embase, PsycINFO, MEDLINE, and the Cochrane Library was conducted on June 11, 2018, and updated on April 30, 2019. A systematic review and meta-analysis of studies published from January 1, 1973, to April 30, 2019, and references of included studies were performed, with data analyzed from January 2 through October 4, 2019.
STUDY SELECTION: English-language studies involving adult marijuana users and reporting cancer development. The search strategy contained the following 2 concepts linked together with the AND operator: marijuana OR marihuana OR tetrahydrocannabinol OR cannabinoid OR cannabis; AND cancer OR malignancy OR carcinoma OR tumor OR neoplasm.
DATA EXTRACTION AND SYNTHESIS: Two reviewers independently reviewed titles, abstracts, and full-text articles; 3 reviewers independently assessed study characteristics and graded evidence strength by consensus.
MAIN OUTCOMES AND MEASURES: Rates of cancer in marijuana users, with ever use defined as at least 1 joint-year exposure (equivalent to 1 joint per day for 1 year), compared with nonusers. Meta-analysis was conducted if there were at least 2 studies of the same design addressing the same cancer without high risk of bias when heterogeneity was low to moderate for the following 4 cancers: lung, head and neck squamous cell carcinoma, oral squamous cell carcinoma, and testicular germ cell tumor (TGCT), with comparisons expressed as odds ratios (ORs) with 95% CIs.
RESULTS: Twenty-five English-language studies (19 case-control, 5 cohort, and 1 cross-sectional) were included; few studies (n = 2) were at low risk of bias. In pooled analysis of case-control studies, ever use of marijuana was not associated with head and neck squamous cell carcinoma or oral cancer. In pooled analysis of 3 case-control studies, more than 10 years of marijuana use (joint-years not reported) was associated with TGCT (OR, 1.36; 95% CI, 1.03-1.81; P = .03; I2 = 0%) and nonseminoma TGCT (OR, 1.85; 95% CI, 1.10-3.11; P = .04; I2 = 0%). Evaluations of ever use generally found no association with cancers, but exposure levels were low and poorly defined. Findings for lung cancer were mixed, confounded by few marijuana-only smokers, poor exposure assessment, and inadequate adjustment; meta-analysis was not performed for several outcomes.
CONCLUSIONS AND RELEVANCE: Low-strength evidence suggests that smoking marijuana is associated with developing TGCT; its association with other cancers and the consequences of higher levels of use are unclear. Long-term studies in marijuana-only smokers would improve understanding of marijuana's association with lung, oral, and other cancers.
TRIAL REGISTRATION: PROSPERO identifier: CRD42018102457.
References
- Cancer Res. 2004 Jun 1;64(11):4049-54 - PubMed
- Am J Epidemiol. 1999 Aug 15;150(4):375-89 - PubMed
- Eur J Intern Med. 2018 Mar;49:2-6 - PubMed
- J Thorac Oncol. 2008 Dec;3(12):1398-403 - PubMed
- Ann N Y Acad Sci. 1976;282:405-15 - PubMed
- Cancer Med. 2018 Mar;7(3):765-775 - PubMed
- N Engl J Med. 1988 Feb 11;318(6):347-51 - PubMed
- Drug Alcohol Depend. 2017 Aug 1;177:299-306 - PubMed
- BMJ. 2003 Sep 6;327(7414):557-60 - PubMed
- Ann Epidemiol. 2010 Apr;20(4):289-97 - PubMed
- Int J Cancer. 2015 Feb 15;136(4):894-903 - PubMed
- Am J Public Health. 1987 Apr;77(4):425-31 - PubMed
- Cancer Epidemiol Biomarkers Prev. 2006 Oct;15(10):1829-34 - PubMed
- Andrology. 2019 Mar;7(2):139-147 - PubMed
- Chem Res Toxicol. 2008 Feb;21(2):494-502 - PubMed
- Ann Intern Med. 2009 Aug 18;151(4):264-9, W64 - PubMed
- Carcinogenesis. 1997 Jul;18(7):1359-63 - PubMed
- AIDS Res Hum Retroviruses. 2009 Feb;25(2):149-56 - PubMed
- Cancer. 1992 Jul 1;70(1):69-76 - PubMed
- Can Urol Assoc J. 2017 Mar-Apr;11(3-4):E138-E142 - PubMed
- Arch Oral Biol. 2015 Dec;60(12):1750-5 - PubMed
- Cureus. 2019 Jan 19;11(1):e3918 - PubMed
- Cancer. 2011 Feb 15;117(4):848-53 - PubMed
- Respir Care. 2016 Nov;61(11):1543-1551 - PubMed
- Chest. 1997 Aug;112(2):319-26 - PubMed
- Oral Oncol. 2004 Mar;40(3):304-13 - PubMed
- Otolaryngol Head Neck Surg. 2008 Mar;138(3):374-80 - PubMed
- J Natl Cancer Inst. 2008 Mar 19;100(6):407-20 - PubMed
- Arch Intern Med. 2006 Jul 10;166(13):1359-67 - PubMed
- Addiction. 2015 Nov;110(11):1699-704 - PubMed
- J Neurooncol. 2004 May;68(1):57-69 - PubMed
- JAMA Pediatr. 2018 Nov 1;172(11):1097-1099 - PubMed
- Cancer. 2012 Nov 1;118(21):5374-83 - PubMed
- J Med Libr Assoc. 2016 Jul;104(3):240-3 - PubMed
- Ann Intern Med. 2018 Dec 18;169(12):890-892 - PubMed
- Stat Med. 2006 Oct 30;25(20):3443-57 - PubMed
- J Thorac Oncol. 2006 Jul;1(6):577-9 - PubMed
- Am J Epidemiol. 1989 Apr;129(4):703-11 - PubMed
- Urology. 2006 Jan;67(1):100-4 - PubMed
- J Oral Pathol Med. 2004 Oct;33(9):525-32 - PubMed
- J Natl Cancer Inst. 1998 Aug 19;90(16):1198-205 - PubMed
- J Natl Cancer Inst. 1993 Jan 6;85(1):19-24 - PubMed
- MMWR Surveill Summ. 2016 Sep 02;65(11):1-28 - PubMed
- Cancer Epidemiol Biomarkers Prev. 1999 Dec;8(12):1071-8 - PubMed
- Addiction. 2008 Oct;103(10):1671-7 - PubMed
- Urology. 2015 Feb;85(2):388-92 - PubMed
- Eur Respir J. 2008 Feb;31(2):280-6 - PubMed
- Biomed Res Int. 2018 Dec 4;2018:1691428 - PubMed
- Cancer Causes Control. 2013 Oct;24(10):1811-20 - PubMed
- Science. 2017 Nov 17;358(6365):941-946 - PubMed
- Cancer Prev Res (Phila). 2009 Aug;2(8):759-68 - PubMed
- Cancer Causes Control. 1997 Sep;8(5):722-8 - PubMed
- Stat Med. 2001 Dec 30;20(24):3875-89 - PubMed
- J Clin Pharmacol. 2002 Nov;42(S1):71S-81S - PubMed
- Am J Respir Cell Mol Biol. 1999 Jun;20(6):1286-93 - PubMed
- JAMA Intern Med. 2016 Dec 1;176(12):1792-1798 - PubMed
- Pharmacol Biochem Behav. 1991 Nov;40(3):657-61 - PubMed
- Sci Signal. 2010 Apr 27;3(119):ra31 - PubMed
- Br J Cancer. 2009 Oct 6;101(7):1207-12 - PubMed
- BMC Cancer. 2015 Nov 11;15:897 - PubMed
- Am J Respir Crit Care Med. 1998 Mar;157(3 Pt 1):928-37 - PubMed
- Cancer. 2009 Mar 15;115(6):1215-23 - PubMed
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