Study register · detailRetrospektive Kohortenstudie · Cancer Risk · 1997
Cannabis use and cancer incidence (California, United States).
Sidney et al.·Cancer Causes & Control
MixedGRADEModerate150 citations
Samplen = 64.855 Pat.
DurationMean follow-up duration 8,6…
ControlNon-use/experimental use
EndpointCancer incidence
Blindingn.a.
DesignRetrospektive Kohortenstudie
”Key finding
No generally increased cancer risk from cannabis use, but indications of increased prostate and cervical cancer risk in those abstinent from tobacco nicotine.
Summary
Retrospective cohort study (n=64.855, mean follow-up 8,6 years): Cannabis use overall was not associated with increased cancer risk (RR=0,9 [95% CI 0,7–1,2] men; RR=1,0 [0,8–1,1] women). In non-smokers, cannabis use was associated with increased prostate cancer risk (RR=3,1 [95% CI 1,0–9,5]) and a tendency toward increased cervical cancer risk (RR=1,4 [95% CI 1,0–2,1]). No association with tobacco-related or colorectal cancers.
P
PopulationAdults aged 15–49 years without a cancer diagnosis at inclusion, n=64.855, Kaiser Permanente Multiphasic Health Checkup (San Francisco and Oakland, California, 1979–1985)
I
InterventionSelf-reported cannabis use (Ever-Use / Current Use vs. non-use/experimental use < 7 lifetime uses)
C
ControlNon-use/experimental use (lifetime use < 7 times)
O
OutcomeNo significantly increased overall cancer risk for Ever-Use (men: RR=0,9, 95%-CI 0,7–1,2; women: RR=1,0, 95%-CI 0,8–1,1); in non-smokers of tobacco cigarettes increased prostate cancer risk (RR=3,1, 95%-CI 1,0–9,5) and borderline increased cervical cancer risk (RR=1,4, 95%-CI 1,0–2,1)
Confidence in the evidence
Very lowLowModerateHigh
Moderate
The third of four GRADE levels, the effect estimate is probably reliable.
The purpose of this retrospective cohort study was to examine the relationship of Cannabis use to cancer incidence. The study population consisted of 64,855 examinees in the Kaiser Permanente multiphasic health checkup in San Francisco and Oakland (California, United States), between 1979-85, aged 15 to 49 years, who completed self-administered questionnaires about smoking habits, including Cannabis use. Follow-up for cancer incidence was conducted through 1993 (mean length 8.6 years). Compared with nonusers/experimenters (lifetime use of less than seven times), ever- and current use of Cannabis were not associated with increased risk of cancer of all sites (relative risk [RR] = 0.9, 95 percent confidence interval [CI] = 0.7-12 for ever-use in men; RR = 1.0, CI = 0.8-1.1 in women) in analyses adjusted for sociodemographic factors, cigarette smoking, and alcohol use. Cannabis use also was not associated with tobacco-related cancers or with cancer of the following sites: colorectal, lung, melanoma, prostate, breast, cervix. Among nonsmokers of tobacco cigarettes, ever having used Cannabis was associated with increased risk of prostate cancer (RR = 3.1, CI = 1.0-9.5) and nearly significantly increased risk of cervical cancer (RR = 1.4, CI = 1.0-2.1). We conclude that, in this relatively young study cohort, Cannabis use and cancer were not associated in overall analyses, but that associations in nonsmokers of tobacco cigarettes suggested that Cannabis use might affect certain site-specific cancer risks.