Preoperative radiotherapy and curative surgery for the management of localised rectal carcinoma

Background: This is an update of the original review published in 2007. Carcinoma of the rectum is a common malignancy, especially in high income countries. Local recurrence may occur after surgery alone. Preoperative radiotherapy (PRT) has the potential to reduce the risk of local recurrence and improve outcomes in rectal cancer. Objectives: To determine the effect of preoperative radiotherapy for people with localised resectable rectal cancer compared to surgery alone. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library; Issue 5, 2018) (4 June 2018), MEDLINE (Ovid) (1950 to 4 June 2018), and Embase (Ovid) (1974 to 4 June 2018). We also searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) for relevant ongoing trials (4 June 2018). Selection criteria: We included randomised controlled trials comparing PRT and surgery with surgery alone for people with localised advanced rectal cancer planned for radical surgery. We excluded trials that did not use contemporary radiotherapy techniques (with more than two fields to the pelvis). Data collection and analysis: Two review authors independently assessed the 'Risk of bias' domains for each included trial, and extracted data. For time-to-event data, we calculated the Peto odds ratio (Peto OR) and variances, and for dichotomous data we calculated risk ratios (RR) using the random-effects method. Potential sources of heterogeneity hypothesised a priori included study quality, staging, and the use of total mesorectal excision (TME) surgery. Main results: We included four trials with a total of 4663 participants. All four trials reported short PRT courses, with three trials using 25 Gy in five fractions, and one trial using 20 Gy in four fractions. Only one study specifically required TME surgery for inclusion, whereas in another study 90% of participants received TME surgery. Preoperative radiotherapy probably reduces overall mortality at 4 to 12 years' follow-up (4 trials, 4663 participants; Peto OR 0.90, 95% CI 0.83 to 0.98; moderate-quality evidence). For every 1000 people who undergo surgery alone, 454 would die compared with 45 fewer (the true effect may lie between 77 fewer to 9 fewer) in the PRT group. There was some evidence from subgroup analyses that in trials using TME no or little effect of PRT on survival (P = 0.03 for the difference between subgroups). Preoperative radiotherapy may have little or no effect in reducing cause-specific mortality for rectal cancer (2 trials, 2145 participants; Peto OR 0.89, 95% CI 0.77 to 1.03; low-quality evidence). We found moderate-quality evidence that PRT reduces local recurrence (4 trials, 4663 participants; Peto OR 0.48, 95% CI 0.40 to 0.57). In absolute terms, 161 out of 1000 patients receiving surgery alone would experience local recurrence compared with 83 fewer with PRT. The results were consistent in TME and non-TME studies. There may be little or no difference in curative resection (4 trials, 4673 participants; RR 1.00, 95% CI 0.97 to 1.02; low-quality evidence) or in the need for sphincter-sparing surgery (3 trials, 4379 participants; RR 0.99, 95% CI 0.94 to 1.04; I 2 = 0%; low-quality evidence) between PRT and surgery alone. Low-quality evidence suggests that PRT may increase the risk of sepsis from 13% to 16% (2 trials, 2698 participants; RR 1.25, 95% CI 1.04 to 1.52) and surgical complications from 25% to 30% (2 trials, 2698 participants; RR 1.20, 95% CI 1.01 to 1.42) compared to surgery alone. Two trials evaluated quality of life using different scales. Both studies concluded that sexual dysfunction occurred more in the PRT group. Mixed results were found for faecal incontinence, and irradiated participants tended to resume work later than non-irradiated participants between 6 and 12 months, but this effect had attenuated after 18 months (low-quality evidence). Authors' conclusions: We found moderate-quality evidence that PRT reduces overall mortality. Subgroup analysis did not confirm this effect in people undergoing TME surgery. We found consistent evidence that PRT reduces local recurrence. Risk of sepsis and postsurgical complications may be higher with PRT. The main limitation of the findings of the present review concerns their applicability. The included trials only assessed short-course radiotherapy and did not use chemotherapy, which is widely used in the contemporary management of rectal cancer disease. The differences between the trials regarding the criteria used to define rectal cancer, staging, radiotherapy delivered, the time between radiotherapy and surgery, and the use of adjuvant or postoperative therapy did not appear to influence the size of effect across the studies. Future trials should focus on identifying participants that are most likely to benefit from PRT especially in terms of improving local control, sphincter preservation, and overall survival while reducing acute and late toxicities (especially rectal and sexual function), as well as determining the effect of radiotherapy when chemotherapy is used and the optimal timing of surgery following radiotherapy.