CHICAGO – Delaying surgery after neoadjuvant therapy for locally advanced rectal cancer for up to 12 weeks does not seem to impact complication rates compared to surgery at 8 weeks or earlier, findings that run counter to results from a major European clinical trial reported in 2016, investigators at the Society of Surgical Oncology Annual Cancer Symposium.
“There’s an increasing trend toward delayed surgery beyond eight to 12 weeks after neoadjuvant therapy (NT) for locally advanced rectal cancer (LARC),” said Campbell Roxburgh, FRCS, PhD, of the University of Glasgow in Scotland. “Although we saw an increase in all complications in patients who had surgery beyond 12 weeks, there were no increases in surgical site complications, grade 3-5 complications, or anastomotic leaks. Before 12 weeks we did not observe increases in any type of complication where surgery was performed prior to or after 8 weeks.”
The study involved 798 patients who had received NT for LARC from June 2009 to March 2014 at Memorial Sloan Kettering Cancer Center in New York. The vast majority – 76% (607) – had rectal resection within 16 weeks of completing NT. Among them, 52% (317) had surgery 5-8 weeks after NT, 38% (229) had surgery at 8-12 weeks post-NT, and 10% (61) had surgery 12-16 weeks after completing NT. Those who had surgery beyond 16 weeks mostly had it deferred because they were undergoing nonoperative management in the case of complete clinical response to treatment or had a comorbidity that prevented earlier surgery, Dr. Roxburgh said.
The complication rate was 42.3% among the patients who had surgery up to 16 weeks after NT, Dr. Roxburgh said. The most common complication was surgical site infection (SSI) in 16.6% (101), followed by a grade 3-5 complication in 10.5% (64) and anastomotic leak in 6.4% (39). Overall complication rates among the two groups that had surgery within 12 weeks were not statistically different from the overall complication rate, Dr. Roxburgh said: 42.5% (138) in the 5- to 8-week group; and 36.7% (84) in the 8- to 12-week group. The 12- to16-week group had a complication rate of 56% (34, P = .022).
Dr. Roxburgh noted that the idea of delaying surgery beyond 8 weeks after NT has been a subject of debate, and that these findings run counter to those reported in the GRECCAR-6 trial (J Clin Oncol. 2016;34:3773-80). That study compared groups that had surgery for rectal cancer at 7 and 11 weeks after neoadjuvant radiochemotherapy and found that those in the 11-week group had higher rates of complications.
Dr. Roxburgh also reported on an analysis of the 12- to 16-week subgroup that found the highest complication rates were among those who had low anterior resection (53% vs. 41% in the 5- to 8-week group and 31% in the 8- to 12-week population), and patients who had a poor treatment response (no T-downstaging, 66% vs. 44% and 33%, respectively). Age, pretreatment and posttreatment TNM stages, surgical approach (open or minimally invasive), and year of treatment did not factor in complication rates in the subgroup analysis, Dr. Roxburgh noted.
The univariate regression analysis determined a trend toward increased rates of all complications in the 12- to 16-week group (P = .081). But the multivariate analysis did not find timing of surgery to be an independent risk factor for all complications, Dr. Roxburgh said. “We believe other factors, including tumor location, the type of NT, operative approach, and treatment response, however, were more important on multivariate analysis,” he said. For example, open surgery had an odds ratio of 1.7 (P = .004).
During the discussion, Dr. Roxburgh was asked what would be the optimal timing for resection after NT in LARC. “I would recommend posttreatment assessment with MRI and proctoscopy between 8 to 12 weeks and in the case of residual tumor or incomplete response to treatment, scheduling surgery at that time,” he said.
Dr. Roxburgh and coauthors reported having no financial disclosures.
SOURCE: Roxburgh C, et al. Society of Surgical Oncology Annual Cancer Symposium .