Background Radical surgery via total mesorectal excision might not be the optimal first-line treatment for early-stage rectal cancer. An organ-preserving strategy with selective total mesorectal excision could reduce the adverse effects of treatment without substantially compromising oncological outcomes. We investigated the feasibility of recruiting patients to a randomised trial comparing an organ-preserving strategy with total mesorectal excision.Methods TREC was a randomised, open-label feasibility study done at 21 tertiary referral centres in the UK. Eligible participants were aged 18 years or older with rectal adenocarcinoma, staged T2 or lower, with a maximum diameter of 30 mm or less; patients with lymph node involvement or metastases were excluded. Patients were randomly allocated (1:1) by use of a computer-based randomisation service to undergo organ preservation with short-course radiotherapy followed by transanal endoscopic microsurgery after 8-10 weeks, or total mesorectal excision. Where the transanal endoscopic microsurgery specimen showed histopathological features associated with an increased risk of local recurrence, patients were considered for planned early conversion to total mesorectal excision. A non-randomised prospective registry captured patients for whom randomisation was considered inappropriate, because of a strong clinical indication for one treatment group. The primary endpoint was cumulative randomisation at 12, 18, and 24 months. Secondary outcomes evaluated safety, efficacy, and health-related quality of life assessed with the European Organisation for Research and Treatment of Cancer (EORTC) QLQ C30 and CR29 in the intention-to-treat population. This trial is registered with the ISRCTN Registry, ISRCTN14422743.

The accuracy of MRI after long-course chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC) has been questioned. We have evaluated our experience of sequential MRI to assess pre-operative downstaging with histopathology correlation. 17 patients with LARC had three MRI scans: MRI 1, before treatment; MRI 2, 6 weeks post-CRT; and MRI 3, pre-operatively. MRI T and N staging were reported, with T3 subdivided into T3a (<5 mm through wall), T3b (1-5 mm), T3c (5-15 mm) and T3d (>15 mm). The maximal wall measurements and a prediction of vascular involvement were also correlated with histopathology. Histopathological agreement with MRI 3 was high: T 82%; N 88% and vascular 73%. Statistically significant (p<0.01) T downstaging was shown in MRI 2 and MRI 3 groups. In the 6 weeks post-CRT scan, T downstaging occurred in 6% of patients, with a further 29.4% showing T3c to T3b downsizing. 41% showed N stage improvement. In the third MRI group pre-surgery, 41.2% showed an MRI T stage improvement, with a further T3 downsizing in 17.6% of patients. 50% of these responders had shown no T stage improvement on their second scan. The sequential scans also showed significant reduction in wall thickness (p<0.01). In conclusion, the pre-operative MRI showed ongoing response to CRT up to 12 weeks post-CRT, which has important clinical implications regarding the most appropriate time to operate. Improved agreement between MRI 3 and histopathology compared with previous studies including only one post-treatment MRI was also demonstrated.

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