In a retrospective cohort study reported in The Lancet Oncology, Lord et al found that high-risk patients with rectal cancer treated with surgery alone who were more likely to benefit from preoperative radiotherapy were better selected using proven magnetic resonance imaging (MRI) prognostic factors than by using the 2020 National Institute for Health and Care Excellence (NICE) guidelines for preoperative radiotherapy.
As stated by the investigators, “Selection of patients for preoperative treatment in rectal cancer is controversial. The new 2020 NICE guidelines, consistent with the National Comprehensive Cancer Network® guidelines, recommend preoperative radiotherapy for all patients except for those with radiologically staged T1-T2, N0 tumors. We aimed to assess outcomes in nonirradiated patients with rectal cancer and to stratify results on the basis of NICE criteria, compared with known MRI prognostic factors now omitted by NICE.”
The study included patients undergoing primary resection for rectal cancer without preoperative radiotherapy at Basingstoke Hospital between January 2011 and December 2016 and St Mark’s Hospital between January 2007 and December 2017. Patients with MRI-detected extramural venous invasion, tumor deposits, and circumferential resection margin involvement were categorized as MRI high-risk for recurrence (local or distant). Outcomes among these patients were compared with patients defined as high-risk according to the NICE criteria of MRI-detected T3+ or N+ status.
A total of 378 patients were included in the analysis, with a median follow-up of 66 months (interquartile range = 44–95 months). Overall, 22 patients had local recurrence and 68 (18%) had distant recurrence.
A total of 248 patients (66%) were classified as high-risk on NICE criteria, compared with 121 patients (32%) according to MRI criteria. On Kaplan-Meier analysis, NICE high-risk patients had poorer 5-year disease-free survival compared with NICE low-risk patients (76%, 95% confidence interval [CI] = 70%–81%, vs 87%, 95% CI = 80%–92%; hazard ratio [HR] = 1.91, 95% CI = 1.20–3.03, P = .0051) but not poorer 5-year overall survival (80%, 95% CI = 74%–84%, vs 88%, 95% CI = 81%–92%; HR = 1.55, 95% CI =0.94–2.53, P = .077).
MRI criteria separated patients into high-risk vs low-risk groups that distinguished both 5-year disease-free survival (66%, 95% CI = 57%–74%, vs 88%, 95% CI = 83%–91%; HR = 3.01, 95% CI = 2.02–4.47, P < .0001) and 5-year overall survival (71%, 95% CI = 62%–78%, vs 89%, 95% CI = 84%–92%; HR = 2.59, 95% CI = 1.62–3.88, P < .0001).
On multivariable analysis, NICE risk assessment was not associated with either disease-free survival (HR = 1.36, 95% CI = 0.83–2.22, P = .22) or overall survival (HR = 1.07, 95% CI = 0.62–1.84, P = .80), whereas MRI high-risk criteria predicted disease-free survival (HR = 2.74, 95% CI = 1.80–4.17, P < .0001) and overall survival (HR = 2.44, 95% CI = 1.51–3.95, P = .00027).
A total of 139 NICE high-risk patients who were defined as low-risk based on MRI criteria had similar 5-year disease-free survival (87%, 95% CI = 80%–92%) compared to the 118 NICE low-risk patients. Thus, 37% of patients in the cohort (139 of 378) potentially would have been overtreated with preoperative radiotherapy on NICE 2020 guidelines. Of the 130 patients defined as low-risk by NICE guidelines, 12 were defined as high-risk on MRI risk assessment and would have potentially not received beneficial treatment.
The investigators concluded, “Compared to previous guidelines, implementation of the 2020 NICE guidelines will result in significantly more patients receiving preoperative radiotherapy. High-quality MRI selects patients with good outcomes (particularly low local recurrence) without radiotherapy, with little margin for improvement. Overuse of radiotherapy could occur with this unselective approach. The high-risk group, with the most chance of benefiting from preoperative radiotherapy, is not well selected on the basis of NICE 2020 criteria and is better identified with proven MRI prognostic factors (extramural venous invasion, tumour deposits, and circumferential resection margin).”
Gina Brown, FRCR, of the Department of Surgery and Cancer, Hammersmith Campus, Imperial College London, is the corresponding author for The Lancet Oncology article.
Disclosure: The investigators reported that there was no funding for the study. For full disclosures of the study authors, visit thelancet.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.