Effects Of Smoking And Smoking Cessation On Non-muscle Invasive Bladder Cancer

Background: Smoking is the most definite and intervenable risk factor for bladder cancer.However,there is no consistent conclusion on whether different smoking characteristics at diagnosis will have an effect on tumor characteristics of non-muscle invasive bladder cancer(NMIBC).The effect of different smoking characteristics at diagnosis and smoking cessation after diagnosis on tumor recurrence is also controversial.Objective: We sought to investigate the correlation between smoking characteristics at diagnosis and tumor characteristics of NMIBC patients,to explore the effect of smoking characteristics at diagnosis on tumor recurrence of NMIBC,to study the effect of smoking cessation after diagnosis on tumor recurrence in NMIBC patients who are current smokers at diagnosis and to verify other clinicopathological factors affecting tumor recurrence of NMIBC.Materials and Methods: Clinicopathological information was collected from patients with primary NMIBC who visited the Second Hospital of Lanzhou University from January 2013 to December 2019,and information about smoking characteristics was collected by telephone follow-up.Univariate and multivariate analyses were performed to analyze the association between smoking characteristics at diagnosis(smoking status,smoking type,smoking intensity,age at smoking initiation,smoking age,smoking index,smoking cessation time before diagnosis,and secondhand smoke exposure or not)and tumor characteristics(pathological grade,clinical T stage,tumor size,tumor number,and risk group)in patients with NMIBC.Survival curves were described using the Kaplan-Meier method,and differential analysis was performed by the Log-Rank method to assess the effects of smoking characteristics at diagnosis,smoking cessation after diagnosis,and other clinicopathological factors on NMIBC tumor recurrence.Finally,Cox proportional hazards model was used for multivariate analysis of risk factors affecting tumor recurrence in NMIBC.Results: A total of 347 patients with NMIBC were included in this study,and the median follow-up time was 32.0(95% CI: 29.4 – 34.6)months,including 274 male patients and 73 female patients.The patients were divided into three groups according to different smoking status at NMIBC diagnosis: 107(30.8%)non-smokers,62(17.9%)former smokers and 178(51.3%)current smokers.The results of the study showed no significant difference in pathological grade(p = 0.158),clinical T stage(p = 0.412),tumor number(p = 0.313),tumor size(p = 0.213)and risk group(p = 0.339)between different smoking status at the time of NMIBC diagnosis.Among current smokers,those who smoked other types of tobacco(hookah,dry-smoke)in addition to cigarettes may have a higher risk of high-grade NMIBC than those who smoked only cigarettes(p = 0.058).There was no difference in the risk of tumor recurrence among NMIBC patients with different smoking status(p = 0.324),and further analysis of the effect of smoking characteristics in each smoking status on tumor recurrence revealed that in NMIBC patients with previous smoking,smoking cessation time before diagnosis significantly affected tumor recurrence(p = 0.047),and the risk of tumor recurrence in former smokers who quit ≥ 15 years before diagnosis was 0.309 times higher than that in patients who quit < 15 years(95% CI: 0.097 – 0.985).Although the effect of other smoking characteristics on NMIBC tumor recurrence was not statistically significant,a trend toward a lower risk of tumor recurrence in patients who smoked for a short period than in patients who smoked for a long period could be observed among smokers,current smokers,and former smokers,while there was no trend toward a difference in the risk of tumor recurrence between patients who smoked light and heavy cigarettes.Among current smokers at NMIBC diagnosis,smoking cessation after diagnosis had no significant effect on tumor recurrence(p = 0.379).The results of the analysis of the effect of other clinicopathological factors on tumor recurrence showed that family history of bladder cancer and tumor risk group were independent factors for tumor recurrence in NMIBC.The risk of tumor recurrence in NMIBC patients with a family history of bladder cancer was 2.405 times higher than that in patients without a family history(95% CI: 1.033 – 5.601,p = 0.042);the risk of tumor recurrence in intermediaterisk patients was 2.458 times higher than that in low-risk patients(95% CI: 1.21 – 4.990,p = 0.013);and the risk of tumor recurrence in high-risk patients was 3.306 times higher than that in low-risk patients(95% CI: 1.734 – 6.303,p < 0.001).Conclusion: There was no significant relationship between smoking status and tumor characteristics of patients at the time of NMIBC diagnosis.Among current smokers,those who smoke unfiltered tobacco may have a higher risk of high-grade NMIBC than those who smoke cigarettes alone.There was no significant difference in the risk of tumor recurrence between patients with different smoking status at the time of NMIBC diagnosis.Only in former smokers,smoking cessation for ≥ 15 years could reduce the risk of tumor recurrence compared with those with smoking cessation for <15 years before diagnosis.Patients who smoked in a short period before NMIBC diagnosis may have a lower risk of tumor recurrence,and smoking age had a greater effect on the risk of tumor recurrence than smoking intensity.Current smokers quit smoking after diagnosis had no effect on tumor recurrence.Family history of bladder cancer and risk group were independent factors of tumor recurrence in NMIBC.