Differences in prognostic relevance of rectal magnetic resonance imaging findings before and after neoadjuvant chemoradiotherapy

Abstract

This retrospective study was designed to compare prognostic relevance of magnetic resonance imaging (MRI) findings before and after neoadjuvant chemoradiotherapy (CRT). From 2002 to 2010, 399 patients who underwent surgery after CRT for rectal cancer (≥T3) and had adequate pre-CRT (mr) and post-CRT (ymr) MRI findings were examined. Factors examined included tumour (T), lymph node (N), mesorectal fascia (MRF), extramural venous invasion (EMVI), and tumour regression grade (TRG). Two Cox proportional hazard models were created using mr and ymr findings separately for overall survival (OS), disease-free survival (DFS), and local recurrence rate (LRR). Among mr findings, only mrEMVI was a significant prognostic factor for OS and DFS. Among ymr findings, ymrN, ymrMRF, and ymrEMVI were significant prognostic factors for OS and DFS, whereas ymrMRF and ymrEMVI were significant prognostic factors for LRR. C-indices tended to be higher for ymr findings than for mr findings (OS, 0.682 vs. 0.635; DFS, 0.660 vs. 0.631; LRR, 0.701 vs. 0.617). Survival outcomes of patients having all ymr risk factors were significantly poor (5-year OS, 52.4%; 5-year DFS, 38.1%; 5-year LRR, 27.7%). ymr findings showed better prognostic significance than mr findings. Among ymr findings, ymrN, ymrMRF, and ymrEMVI were independent prognostic factors for oncologic outcomes.

Oncologic Outcomes Associated With MRI-detected Extramural Venous Invasion (mrEMVI) in Rectal Cancer

“…Both found a significantly higher risk of recurrence for ymrEMVI-positive patients; Kim et al with a RR of 4.79 (95%CI 1.49-15.36, P ¼ 0.0085) 30 and Song et al with a RR of 1.93 (95%CI 1.39-2.67, P ¼ 0.0001). 37 Two other authors reported 3-year DFS rates, again showing a significantly higher recurrence risk with ymrEMVI-positive status; Chand et al with a RR of 2.70 (95%CI 1.75-4.16, P < 0.0001) 26 and Prampolini et al with a RR of 3.53 (95%CI 1.36-9.15, P ¼ 0.0095). 36 No study reported 1-year DFS rates.…”

“…39 Two other authors provided 5-year LR rates, but none of them were statistically significant for mrEMVI-positive status; Cho et al with a RR of 1.53 (95%CI 0.51-4.63, P ¼ 0.4497) 27 and Song et al with a RR of 1.62 (95%CI 0.74-3.51, P ¼ 0.2245). 37 Meng et al were the only authors to provide 3-year LR rates, but the association was not statistically significant with a RR of 1.88 (95%CI 0.12-29.19, P ¼ 0.6536). 34 No study reported 1-year LR rates.…”

“…Lee et al did not find a significant difference for ymrEMVI-positive patients with a HR of 1.97 (95%CI 0.88-4.39, P ¼ 0.0991), 33 while Song et al showed a statistically significant lower survival for ymrEMVI-positive status with a HR of 1.73 (95%CI 1.06-2.82, P ¼ 0.0283). 37 Song et al were the only authors to report 5-year OS rates, showing a significantly lower survival in ymrEMVI-positive patients with a RR of 2.58 (95%CI 1.58-4.21, P ¼ 0.0002).…”

“…Three studies incorporating 846 patients reported 5-year DFS rates, 27,30,37 which led to a pooled RR estimate of 1.87 (95%CI 1.41-2.48, P < 0.0001; Fig. 2B) for increased risk of recurrence with an mrEMVI-positive status.…”

“…Cho et al did not find a significant difference in 5-year OS with a RR of 1.39 (95%CI 0.35-5.55, P ¼ 0.6386) for mrEMVI-positive patients, 27 whereas Song et al showed a statistically significant lower OS for mrEMVI-positive status with a RR of 2.22 (95%CI 1.29-3.83, P ¼ 0.0041). 37…”