Proforma-based reporting in rectal cancer

Abstract

The improvements in outcomes associate with the use of preoperative therapy rather than postoperative treatment means that clinical teams are increasingly reliant on imaging to identify high-risk features of disease to determine treatment plans. For many solid tumours, including rectal cancer, validated techniques have emerged in identifying prognostic factors pre-operatively. In the MERCURY study, a standardised scanning technique and the use of reporting proformas enabled consistently accurate assessment and documentation of the prognostic factors. This is now an essential tool to enable our clinical colleagues to make treatment decisions. In this review, we describe the proforma-based reporting tool that enables a systematic approach to the interpretation of the magnetic resonance images, thereby enabling all the clinically relevant features to be adequately assessed.

Figure 1

Polypoidal lesions tend to have a smaller invasive front and extend beyond the rectal wall through the stalk.

Figure 2

Annular ulcerating tumours are characterized by a central ulcer/crater with raised rolled edges. They invade at the ulcer crater with either a smooth or more nodular infiltrating border. The latter is associated with a poorer prognosis and higher rate of metastatic failure^[1–6].

Figure 3

The height of the tumour is given from the anal verge as this is a useful reference point for surgeons. It is measured from the lowest point to the raised rolled edge of the tumour to the anal verge.

Figure 4

MRI diagnosis of a tumour spread beyond the muscularis propria is based upon the presence of tumour signal extending into the perirectal fat with a broad-based bulging or nodular configuration in continuity with the intramural portion of the tumour.

Figure 5

At this level there is no mesorectum, which, higher in the rectum, acts as a protective barrier to contain tumour. Therefore any spread beyond the muscularis propria would result in exposure of tumour at the margins if an ultra-low TME or conventional plane APE is undertaken.

Figure 6

MRI is the only imaging modality that has been shown to consistently demonstrate extramural vascular invasion in rectal cancer^[7] and is depicted as discrete serpiginous or tubular projections of intermediate signal intensity into perirectal fat, following the course of a visible perirectal vein.

Figure 7

Lymph nodes should only be evaluated on high resolution (minimum in plane resolution 0.6×0.6 mm, slice thickness 3 mm). Nodes can then be classified according to their appearance. Uniform, homogenous signal intensity nodes are not considered to be suspicious. Nodes are judged suspicious if they have irregular borders or mixed signal intensity or both^[8].

Figure 8

Measurements are taken for the distance of tumour to the mesorectal fascia, the potential CRM of the tumour. A potentially positive margin is defined as tumour lying within 1 mm of the mesorectal fascia.

Figure 9

We record the location of the node, size, site and if there are any suspicious features according to the morphological criteria stated above.

Figure 10

Post chemoradiotherapy assessment of tumour regression. For those patients who received preoperative chemoradiotherapy we used a tumour regression grade analysis, grade 1–5, modified from Dworak et al.^[9] This is known to be a better predictor for outcome after treatment compared with T stage.