Comorbidity alterations between time for diagnosis and radical cystectomy in patients with muscle invasive bladder cancer undergoing neoadjuvant chemotherapy

Background: Comorbidity alterations during neoadjuvant chemotherapy (NAC) in patients with muscle invasive bladder cancer (MIBC) are not well studied. Comorbidity-estimates are mainly based on calculations at diagnosis. It is unknown if comorbidities alter in this patient group. This study aimed to investigate if comorbidity alterations during treatment need to be considered, for scientific evaluations. Methods: A retrospective study of comorbidity alterations on MIBC patients undergoing NAC using age adjusted Charlson Comorbidity Index (CACI). We identified 684 patients between 2007–2022 from four Swedish cystectomy centers, a total of 320 were enrolled in the study. Inclusion criteria were nondisseminated MIBC, cT2–4aN0M0, NAC-treatment or NAC-eligibility. Medical files were reviewed and CACI were assessed and graded at three checkpoints during treatment: At diagnosis, post-NAC and pre-surgery. The cohort was divided into three subgroups, NAC complete, NAC incomplete and NAC-eligible. Data was retrospectively analyzed in SPSS Statistics 29.0 using descriptive statistics, one-way analysis of variance (ANOVA) and t-test. Results: The total cohort (n=320) had an increase in CACI, 0.11 CACI points, between diagnosis and prior to surgery [95% confidence interval (CI): 0.06–0.15, P<0.001]. The NAC-incomplete group had the highest increase in CACI, 0.21 CACI points from diagnosis to pre-surgery (95% CI: 0.03–0.39, P=0.01). The NAC-complete group also had an increase in CACI, 0.11 CACI points from diagnosis to pre-surgery (95% CI: 0.06–0.15, P<0.001). The NAC-eligible group had no significant CACI-alterations. The most common events causing an increase in CACI was suspected peptic ulcer (85.2%). Conclusions: There is a statistically significant increase of comorbidity in the total cohort as well as for two of the three subgroups, the NAC complete group and the NAC incomplete group. However, the increases are subtle and of limited clinical significance. This suggests that regardless of adverse events, complications, or progression, comorbidities only slightly change over time in the patient group. All together, answering the primary question if a comorbidity measurement at any moment on the timeline is sufficient.