Limitations
REGRESSION, ONCOLOGY
This study has several limitations. The retrospective design allowed for selection bias and confounding. Although reported AEs were assigned according to CTCAE criteria, this process was reliant on variable AE reporting standards throughout the study period. While differences in baseline characteristics, such as age and year of treatment, were controlled for using Cox regression multivariable analysis, unmeasured residual confounding could exist. There was a substantial difference in follow-up time between the groups due to the increasing use of gemcitabine and docetaxel since 2019. Longer follow-up and larger sample size could have yielded differences in oncological outcomes such as PFS and OS. Treatment with BCG was administered using our institutional protocol, with patients sometimes receiving one-third dosing in combination with IFN-α-2b; however, neither of these changes in treatment protocol has been associated with adverse oncological outcomes compared with the strict 3-year full-dose Southwest Oncology Group maintenance regimen.