Smoking and pancreatic cancer: a sex-specific analysis in the Multiethnic Cohort study

To examine whether the detrimental smoking-related association with pancreatic cancer (PC) is the same for women as for men.

We analyzed data from 192,035 participants aged 45-75 years, enrolled in the Multiethnic Cohort study (MEC) in 1993-1996. We identified PC cases via linkage to the Hawaii and California Surveillance, Epidemiology, and End Results Program cancer registries through December 2017.

During a mean follow-up of 19.2 years, we identified 1,936 incident PC cases. Women smokers smoked on average less than men smokers. In multivariate Cox regression models, as compared with sex-specific never smokers, current smokers had a similar elevated risk of PC for women, hazard ratio (HR) 1.49 (95% CI 1.24, 1.79) and as for men, HR 1.48 (95% CI 1.22, 1.79) (p_{heterogeneity}: 0.79). Former smokers showed a decrease in risk of PC for men within 5 years, HR 0.74 (95% CI 0.57, 0.97) and for women within 10 years after quitting, HR 0.70 (95% CI 0.50, 0.96), compared with their sex-specific current smokers. Both sexes showed a consistent, strong, positive dose-response association with PC for the four measures (age at initiation, duration, number of cigarettes per day, number of pack-years) of smoking exposure among current smokers and an inverse association for years of quitting and age at smoking cessation among former smokers (all p_trend's < 0.001).

Although MEC women smoke on average less than their men counterparts, the smoking-related increase in PC risk and the benefits of cessation seem to be of similar magnitudes for women as for men.