Smoking increases rectal cancer risk to the same extent in women as in men: results from a Norwegian cohort study
Permanent link
https://hdl.handle.net/10037/6529Date
2014-05-06Type
Journal articleTidsskriftartikkel
Peer reviewed
Author
Parajuli, Ranjan; Bjerkaas, Eivind; Aage, Tverdal; Le Marchand, Loïc; Weiderpass, Elisabete; Gram, Inger TorhildAbstract
Background: Smoking has recently been established as a risk factor for rectal cancer. We examined whether the
smoking-related increase in rectal cancer differed by gender.
Methods: We followed 602,242 participants (49% men), aged 19 to 67 years at enrollment from four Norwegian
health surveys carried out between 1972 and 2003, by linkage to Norwegian national registries through December
2007. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated by fitting Cox proportional hazard
models and adjusting for relevant confounders. Heterogeneity by gender in the effect of smoking and risk of rectal
cancer was tested with Wald χ2.
Results: During a mean follow-up of 14 years, 1,336 men and 840 women developed invasive rectal cancer. Ever
smokers had a significantly increased risk of rectal cancer of more than 25% for both men (HR = 1.27, 95% CI = 1.11-1.45)
and women (HR = 1.28, 95% CI = 1.11-1.48) compared with gender-specific never smokers. Men smoking ≥20 pack-years
had a significantly increased risk of rectal cancer of 35% (HR = 1.35, 95% CI = 1.14-1.58), whereas for women, it
was 47% (HR = 1.47, 95% CI = 1.13-1.91) compared with gender-specific never smokers. For both men and women,
we observed significant dose–response associations between the risk of rectal cancer for four variables [Age at
smoking initiation in years (both ptrend <0.05), number of cigarettes smoked per day (both ptrend <0.0001), smoking
duration in years (ptrend <0.05, <0.0001) and number of pack-years smoked (both ptrend <0.0001)]. The test for
heterogeneity by gender was not significant between smoking status and the risk of rectal cancer (Wald χ2,
p -value; current smokers = 0.85; former smokers = 0.87; ever smokers = 1.00).
Conclusions: Smoking increases the risk of rectal cancer to the same extent in women as in men.
Description
This papers is part of Ranjan Parajuli's doctoral thesis, available in Munin at http://hdl.handle.net/10037/6610
Publisher
BioMed CentralCitation
BMC Cancer (2014), vol. 14:321Metadata
Show full item recordCollections
The following license file are associated with this item: