The study relied on people recalling their smoking history over many decades, which introduced a degree of uncertainty into the findings
Competing interests D.E.Rojas, M.M.McCartney, E.Borras, T.L.Hicks, and T.T.Lam have no conflicts of interest to report
The reference lists of the remaining studies were reviewed, yielding 13 potentially relevant studies, all 13 of these studies were excluded because they lacked a cohort design (Supplementary material 2)
According to the 2011 National Survey on Drug Use and Health, 16.7 million people age 12 or older reported using marijuana within the 30 days prior to taking the survey
As the cancer cells grow, they move beyond their original location, affecting the healthy tissues around them