Preoperative assessment of retrorectal tumours.

BACKGROUND: Retrorectal tumours present diagnostic and surgical challenges. This study aimed to identify whether preoperative imaging and/or biopsy provide diagnostic accuracy. METHODS: A consecutive series of patients who had undergone excision of a retrorectal tumour were identified from a database (2002-2013). Details of patient demographics, preoperative presentation, imaging, biopsy, surgical procedure, and gross and microscopic pathology were reviewed. Preoperative imaging and/or biopsies were compared with eventual pathology findings. RESULTS: In total, 76 patients were identified, all of whom had undergone preoperative cross-sectional imaging whereas only 22 had preoperative biopsy. Imaging correctly discriminated benign from malignant tumours in 72 of the 76 patients (specificity 97 per cent, sensitivity 88 per cent, positive predictive value 88 per cent and negative predictive value 97 per cent). The corresponding values for preoperative biopsy (benign versus malignant) were 100, 83, 100 and 93 per cent. None of the four patients who were assessed incorrectly as having benign or malignant disease on imaging would have undergone an alternative procedure had this been known before surgery. Preoperative biopsy did not significantly influence patient management, and the absence of preoperative biopsy had no detrimental effect; a definitive preoperative histological diagnosis would not have influenced subsequent management. CONCLUSION: Preoperative imaging was accurate in the assessment of retrorectal tumours, whereas biopsy did not add to the surgical strategy.

MRI assessment of the bony pelvis may help predict resectability of rectal cancer.

OBJECTIVE: The outcome after surgical treatment of rectal cancer may be influenced by the technical difficulty of the operation, which is thought to be affected by pelvic size. The aim of this study was to examine the association between bony pelvic dimensions and CRM involvement. PATIENTS AND METHODS: All patients with primary rectal cancer between December 1999 and January 2002 were studied. Staging was performed by pelvic MRI. Nine pelvic dimensions were measured from the MR images on a workstation. Pathology reports were obtained for all patients and the mesorectal specimen was examined. Technical difficulty was assessed by circumferential resection margin (CRM) involvement. RESULTS: Of 126 patients with primary rectal cancer, 88 had staging MRI and rectal excision; there were significant differences between the sexes in all 9 pelvic dimensions (P < 0.05). In females, the interspinous diameter was significantly shorter in patients with CRM involvement compared with patients with a negative CRM. In female patients predicted to have a negative CRM, the anteroposterior diameter of the inlet, the anteroposterior diameter of the midplane and the transverse diameter of the midplane (interspinous distance) were significantly shorter in patients who actually had a positive CRM compared with those in whom the CRM was negative. In male patients, there was no correlation between pelvic dimensions and CRM status. CONCLUSIONS: In certain patients with rectal cancer, CRM positivity may be predicted from pre-operative MRI pelvic measurements. This may influence the choice of adjuvant therapy.