Smoking cessation prolongs survival in female cancer survivors - the Danish nurse cohort.

PURPOSE: To explore smoking cessation between cancer survivors and cancer-free women, and the potential survival benefits from smoking cessation in cancer surviving women. METHOD: We pooled 46,334 responses from the Danish Nurse Cohort. The cohort consists of female nurses, who were invited for surveys in 1993, 1999 and 2009. Participants were linked to nationwide registries on hospitalization, cause of death and migration through 2016. Odds for smoking cessation by cancer diagnosis were computed in propensity score matched logistic regression models, while survival by postdiagnosis smoking cessation was estimated in cox proportional hazards models. RESULTS: Eligible for analysis were 7841 women (mean age = 56.7 years, SD ± 7.2), who were smokers at baseline and survived to the next follow-up survey. Of these, 545 women were diagnosed with cancer and matched by propensity score (1:2) with 1090 cancer-free women. Odds for smoking cessation were significantly higher in cancer-diagnosed women compared to their cancer-free peers (OR = 1.31, 95% CI: 1.06-1.61). Moreover, mortality risk was significantly lower among cancer survivors who stopped smoking (HR = 0.64, 95% CI: 0.46-0.91), compared to persistent smokers. CONCLUSIONS: The results suggest considerable survival benefits from smoking cessation in cancer surviving female nurses, and that the time surrounding cancer diagnosis may serve as a teachable moment for smoking cessation. However, due to substantial methodological limitations embedded in the study, careful interpretation of the presented results is warranted. Future studies are needed to demonstrate the effects of diagnosis on smoking cessation as well as the effects of smoking cessation on survival in female cancer populations.

Joint tobacco smoking and alcohol intake exacerbates cancer risk in women- the Danish nurse cohort.

PURPOSE: To explore separate and combined tobacco and alcohol use and risk of overall, smoking-related, alcohol-related, breast and gynecological cancers in women. METHOD: Questionnaires from 19,898 women in The Danish Nurse Cohort in 1993 were linked to registries on hospitalizations, death causes and migration until Dec 2016. Cancer risk by tobacco and alcohol was estimated using Cox proportional hazards models. RESULTS: 16,106 nurses, aged >44 years (mean = 56), were eligible for analysis. Throughout 23 years (mean follow-up = 18.8 years) overall cancers counted 4,968. Of these, 1,897, 2,231, 1,407 and 579 events were smoking-related, alcohol-related, breast cancers and gynecological cancers. Increased risks of overall, smoking-related, and breast cancer were observed for current smoking and excess alcohol intake (>14 units/week), separately, compared to never smoking and light drinking (1-7 units/week) respectively. Moderate drinking (8-14 units/week) increased the risk of alcohol-related and breast cancer. Additional risk increases were observed among smokers drinking alcohol above light levels for overall, smoking-related, alcohol-related and breast cancer (HR = 1.40, 95% CI:1.30-1.51, HR = 1.72, 95% CI:1.52-1.94, HR = 1.33, 95% CI:1.26-1.40, HR = 1.32, 95% CI:1.15-1.53, respectively), compared to non-smokers drinking lightly. These risks increased further for smokers drinking above moderate levels (HR = 1.49, 95% CI:1.36-1.63, HR = 1.97, 95% CI:171.-2.26, HR = 1.40, 95% CI:1.22-1.60, HR = 1.33, 95% CI:1.12-1.57, respectively). No significant associations were found for gynecological cancer. CONCLUSIONS: Smoking and alcohol, both separately and combined, increased risks of overall, smoking-related, alcohol-related and breast cancer; combined use resulted in incremental risk increases. Co-use of smoking and alcohol represent an extensive threat to public health; thus, prevention could benefit from combined targeting.