The goal of this study was to investigate the dynamic changes and consequences of radical cystectomy on quality of life in patients who have overcome muscle-invasive bladder cancer. Participants in this trial had been diagnosed with muscle-invasive bladder cancer. Each patient’s quality of life was evaluated using the World Health Organization Quality of Life-Brief questionnaire to assess consecutive patients’ quality of life questionnaire. Researchers used kernel smoothing to demonstrate the dynamic shifts in domain and item scores following therapy; they used kernel smoothing. After accounting for demographic and clinical variables, they used mixed-effects models to analyze how radical cystectomy affected the scores on each item and domain of the World Health Organization Quality of Life-Brief questionnaire. About 10 patients with muscle-invasive bladder cancer were asked to fill out the WHO Quality of Life-Brief questionnaire 397 times. About 42 of them had a complete cyst removal performed. Compared to the general population, patients with radical cystectomy tended to have greater education and fewer co-morbidities (such as diabetes and cardiovascular disease). Results from the mixed-effects models construction showed that the 3 primary domains and their items were equally matched between patients who underwent radical cystectomy and those who underwent bladder sparing, except for select items of the physical domain. Investigators used the kernel smoothing method to discover that patients in stages III and IV who had undergone radical cystectomy experienced greater improvements in their sleep and rest quality over the course of more than 5 years. Radical cystectomy did not improve stage II patients’ “sleep and rest” score compared to those with a bladder-sparing operation. Radically removing the bladder can help patients with stages III and IV of bladder cancer slumber peacefully.