Discussion
The prevalence of being overweight or obese has increased by 27.5% for adults, and obesity continues to be a major health problem worldwide17. The risk for multiple medical problems that can adversely affect surgical outcomes is increased in obese patients18. The relationship of BMI with bladder cancer and radical cystectomy has been the subject of scientific research in the past decade. However, in the literature, the results regarding the effect of obesity on the surgical and oncological outcomes of patients after RC for BC are still contradictory 2,9-12. In this study, we evaluated the effect of BMI on oncologic and surgical outcomes in patients who underwent radical RC for BC. We found that the operation time and oral feeding start were longer and major complications were more common in obese patients. The results revealed that the mean OS, CSS, RFS, and MFS was shorter in cases with BMI>29.9kg/m2 compared with other BMI groups, however, the differences were not statistically significant.
Due to greater technical challenges, many studies reported that increased BMI is independently associated with perioperative and postoperative risks after RC. In a study on 1293 patients who underwent radical cystectomy, Tyson MD et al., by comparing patients with BMI<30 and patients with BMI ≥30, found that obese patients had longer operation time and more renal failure and \soutthey noted no differences in 30-day mortality after RC 19. In another study, Maurer \soutand T et al, by comparing normal weight, and overweight patients who underwent RC, revealed that there was no significant difference according to intraoperative blood transfusion rate, postoperative TNM stage, and postoperative complications. They noted that the time of surgery was significantly prolonged and postoperative bleeding was more common in overweight patients13. After analyzing the data of 671 patients who underwent radical cystectomy, Gierth M et al reported that, there was no significant relationship between obesity and tumor stage, grade, lymph node metastasis, blood loss, urinary diversion type, and 90-day mortality. Severe complications within 30 days after RC, blood transfusion rates were higher and the mean operation time was longer in patients with BMI ≥30 kg/m2 compared to the other BMI groups 20. Another study by Lee et al showed that number of complications is higher in obese patients, but complication severity was similar between BMI groups 21. In our study, statistically significant major complication rate was observed in Group 3 compared to Group 1 and 2 (p=0.025 ).
Increased BMI is associated with risk for many cancers, including urological cancers. It is also thought that cancer is associated with poor prognoses 22-24. Many studies \soutevaluating examined the relationship between obesity and oncological outcomes of RC2,11,12,20,25. In multivariable analysis of 4118 RC patients due to BC, Chromecki et al found that patients with BMI> 30 had higher disease recurrence (HR 1.67, 95% CI 1.46 – 1.91, P < 0.001), lower CSS (HR 1.43, 95% CI 1.24 – 1.66, P < 0.001), and lower OS (HR 1.81, CI 1.60 – 2.05, P < 0.001). They thought that, this finding might be related to the metabolic syndrome seen in obese patients 25. In another study, Dabi et al. found that the risk of disease recurrence or cancer-specific mortality increased by 1.5 fold for obese patients. They reported that increased BMI is an independent prognostic factor for oncological results of BC patients who underwent RC 2. In literature, conflicting findings have also been reported. In a retrospective study, which analyzed the data of 300 patients who underwent cystectomy (radical or partial) due to BC and whose median follow-up was 39 months, Hafron J et al showed that the increase in BMI has no effect on OS or disease-specific survival in univariate or multivariate analysis. In addition, they found that age over 65 years, tumor stage, smoking, and the positive tissue margin were significant factors affecting OS 11. Also, Gierth et al. found that increased BMI had no effect on survival and not associated with more aggressive tumor biology 20. On the other hand, Kwon et al reported that overweight and obesity were associated with favorable pathological features and prognosis in patients with bladder cancer undergoing radical cystectomy [12]. Our study showed that the increase in BMI does not have a statistically significant negative effect on DSS and OS
The surgical approach is another point of discussion. The guidelines have recommended that none of the surgical approaches (open-, laparoscopic- or robotic RC) has clearly shown superiority in terms of functional or oncological results. In the CORAL study, a prospective study by Khan et al, the authors found no difference in 5-yr RFS, CSS, and OS rates of patients who underwent open, laparoscopic and robotic radical cystectomy for management of bladder cancer. Minimally invasive techniques achieved equivalent oncological outcomes to the gold standard of ORC 26. After analyzing robot-assisted radical cystectomy (RARC) cases, Butt et al found that, overweight and obese patients had similar complication rates, operative times and estimated blood loss compared with patients with normal BMI 27. Ahmadi et al showed that, BMI was not associated with significant differences in peri-operative, pathological or early oncological outcomes in patients undergoing RARC 28. In our study, we did not include the RARC cases, as the number of those patients was very low. We found no statistically significant effect of surgical approach (open or laporoscopic) in terms of OS and CSS.
The present study has some limitations. Data collection and analysis was retrospective and non-randomized. Therefore, unidentified confounding variables may have an effect on the results. Another limitation was the performance of procedures by 8 high-volume surgeons in 6 different centers. However, this limitation is always present in such multicenter studies. Moreover, lack of central pathologic assessment is also a limitation.