Abdominal wall complications after urological surgery

Abstract: Background Abdominal wall complications such as incisional hernia, bulging, and pain are known complications of surgery in the abdominal cavity. Most previous studies have been conducted on general surgical procedures, whereas few have been conducted on patients treated for urological cancer. The urological organs differ from other abdominal organs since they are situated outside the peritoneum i.e., retroperitoneal. It has also previously been hypothesized that the levels of androgens such as testosterone may play a crucial role in the formation of inguinal hernia. The aims of this thesis were to: I) Investigate and compare the incidence and risk factors for development of incisional hernia after prostate cancer and renal cell carcinoma surgery with either open or minimally invasive surgery. II) Investigate the extent of muscle atrophy in the rectus abdominis after open renal cell carcinoma surgery, and whether the extent of muscle atrophy after surgery relates to degree of pain from the abdominal wall. III) Test the hypothesis that low bioavailable levels of testosterone caused by treatment for prostate cancer may be related to an increased risk for development of inguinal hernia. Methods Study I. All men with prostate cancer who underwent radical prostatectomy in Sweden between 2004 and 2013 were identified from the National Prostate Cancer Register Sweden (NPCR) and linked with the National Patient Register (NPR) to determine comorbidity and diagnosis of or surgery for incisional hernia. Study II. All patients diagnosed with renal cell carcinoma in Sweden between January 2005 and November 2015 were identified in the Renal Cell Cancer Database Sweden (RCCBaSE) n=9638. Of these, 6417 were included in the analyses to determine the cumulative rate of incisional hernia after surgery comparing open or minimally invasive surgery for radical nephrectomy or partial nephrectomy. Patient-related risk factors for incisional hernia were identified. Study III. All men that had not received curative treatment for prostate cancer identified in the Prostate Cancer Database Sweden (PcBaSe) between 1st January 2008 and 31st December 2016 were included in a population-based nested case-control study on risk for inguinal hernia while on androgen deprivation therapy (ADT). Cases were men diagnosed with inguinal hernia or had undergone inguinal hernia repair (n=1,324) and controls were men without inguinal hernia, matched only on birth year (n=13 240). A conditional multivariate logistic regression model was used to assess any temporal association between ADT and inguinal hernia adjusting for marital status, education level, prostate cancer risk category, Charlson Comorbidity Index, type of ADT, time since prostate cancer diagnosis, and primary prostate cancer treatment. Study IV. Forty-three patients were included in a randomized study on patients undergoing open renal cancer surgery with a transverse unilateral incision at Karolinska University Hospital, Stockholm, between 2016 and 2019. The thickness and attenuation of abdominal wall muscles were measured on computer tomography (CT) scan before surgery and on two separate occasions after surgery. Three months postoperatively, patients were asked to report pain from the abdominal wall in a questionnaire. Repeated measure ANOVA was used to determine any decrease in rectus abdomni muscle thickness at first and second postoperative CT scans. Ordinal regression was used to determine correlation between patient-reported degree of pain three months after surgery and change in abdominal wall muscle thickness (>30 % decrease or <30% decrease) age (<65 year and >65 year), or gender. Results Study I. During the study period, 19,743 men underwent radical prostatectomy for prostate cancer. The cumulative rate of incisional hernia five years after surgery was 1.4% (95% confidence interval (CI95%) 1.2–1.7%) and 2.7% (CI95% 2.3%-3.2%) for open or minimally invasive radical prostatectomy. Age above the median was associated with increased risk for incisional hernia in both groups. Prostate volume above the median and lymph node dissection were associated with increased risk for incisional hernia in the minimally invasive group (p<0.05 for all). Study II. Of the 6,417 patients that underwent surgery for renal cell carcinoma between January 2005 and November 2015, 5,216 (81%) underwent open surgery and 1,201 (19%) underwent minimally invasive surgery. In total, 140 patients were diagnosed with incisional hernia. The cumulative rate of incisional hernia after five years for all renal cell carcinoma surgery was 5.2 % (95% confidence interval (CI) 4.0%-6.4%) after open surgery and 2.4% (CI 1.0%-3.4%) after minimally invasive surgery (p<0.05). In Cox proportional hazard analysis, age and left-sided surgery were associated with incisional hernia in the open surgery group (both p<0.05). In the minimally invasive group, no statistically significant risk factors for incisional hernia were found. Study III. Odds Ratio (OR) for diagnosis or repair of inguinal hernia 0-1 years after start of ADT was 0.5 (95% confidence Interval (CI)) 0.38-0.68), between 1 and 3 years after, the OR was 0.35 (95% CI 0.26-0.47), 3-5 years after, the OR was 0.39 (95% CI 0.26-0.56), 5-7 years after, the OR was 0.6, (95% CI: 0.41-0.97), and > 9 years after, the OR was 3.68 (95% CI 2.45-5.53). Study IV. Compared to preoperative CT scans, there was a decrease in abdominal wall muscle thickness from 8.9 ± 2.2 mm to 6.2 ± 2.3 mm (P<0.001) at the first and to (5.2 ± 1.9 mm, P<0.001) at the second postoperative scan. Age below 65 years was associated with a statistically significant odds of perceiving more severe pain from the abdominal wall after surgery (OR 5.20 CI95% 1.16 to 23.41). However, no statistically significant association between the extent of muscular atrophy and level of pain was observed. Conclusions Study I. The rate of incisional hernia is significantly higher after minimally invasive radical prostatectomy for prostate cancer compared to open radical prostatectomy. Awareness of the risk and appliance of appropriate surgical technique may lower the risk. Study II. Open surgery for renal cell carcinoma is associated with a significantly higher risk for developing incisional hernia than minimally invasive surgery. When open surgery for renal cell carcinoma is the only option, attention should be taken when choosing placement for incision and when closing the wound. Future studies are needed to find strategies to reduce the risk for abdominal wall complications after open renal cell carcinoma surgery. Study III. The marked increase in OR for inguinal hernia after 9 years of ADT supports the hypothesis that low testosterone levels increase the risk for inguinal hernia. The apparently low risk for inguinal hernia during the first eight years on ADT is likely caused by selection of men with advanced cancer unlikely to be diagnosed or treated for inguinal hernia. Study IV. Flank incisions lead to abdominal wall muscular atrophy that progresses over time, but the impact of atrophy on pain is difficult to predict. Low age is one of the most important factors for persisting pain.