Follow-up of colorectal cancer and patterns of recurrence.

Colorectal cancer is one of the commonest cancers detected as also amongst the most common causes of cancer death. Survival has improved due to better disease understanding and treatment; however, a substantial proportion of patients recur after curative intent therapy. In this article, we will discuss the imaging features of recurrent colorectal cancer and the role of the radiologist in its management.

Minimally invasive versus open pelvic exenterations for rectal cancer: a comparative analysis of perioperative and 3-year oncological outcomes.

BACKGROUND: This study compared the surgical and oncological outcomes of open and minimally invasive pelvic exenteration. METHODS: Patients who underwent pelvic exenterations for primary locally advanced rectal cancers with invasion of the urogenital organs (central and anterior disease) between August 2013 and September 2020 were reviewed retrospectively. Patients were categorized as undergoing open or minimally invasive surgery (MIS) and these groups were compared for perioperative outcomes and 3-year survival (overall, recurrence-free and local relapse-free survival). Multivariable Cox regression analysis was performed to assess the independent influence of approach of surgery and cancer features on recurrence-free survival (RFS). RESULTS: Of the 158 patients who underwent pelvic exenteration, 97 (61.4 per cent) had open exenterations and 61 (38.6 per cent) patients had an MIS resection (44 patients (72 per cent) using laparoscopy and 17 (28 per cent) using robotic surgery). There were 96 (60.8 per cent) total pelvic exenterations and 62 (39.2 per cent) posterior pelvic exenterations. MIS exenterations had significantly longer operative times (MIS versus open: 640 mins versus 450 mins; P < 0.001) but reduced blood loss (MIS versus open: 900 ml versus 1600 ml; P < 0.001) and abdominal wound infections (MIS versus open: 8.2 versus 17.5 per cent; P = 0.020) without a difference in hospital stay (MIS versus open: 11 versus 12 days; P = 0.620). R0 resection rates and involvement of circumferential resection margins were similar (MIS versus open: 88.5 versus 91.8 per cent, P = 0.490 and 13.1 versus 8.2 per cent, P = 0.342 respectively). At a median follow-up of 29 months, there were no differences in 3-year overall survival (MIS versus open: 79.4 versus 60.2 per cent; P = 0.251), RFS (MIS versus open: 51.9 versus 47.8 per cent; P = 0.922) or local relapse-free survival (MIS versus open: 89.7 versus 75.2 per cent; P = 0.491. On multivariable analysis, approach to surgery had no bearing on RFS, and only known distant metastasis, aggressive histology and inadequate response to neoadjuvant radiation (pathological tumour regression grade greater than 3) predicted worse RFS. CONCLUSION: MIS exenterations documented longer procedures but resulted in less blood loss and fewer wound infections compared with open surgeries. In the setting of an experienced centre, the hospital stay, R0 resection rates and oncological outcomes at 3 years were similar to those of open exenterations.

Can Post-Treatment MRI Features Predict Pathological Circumferential Resection Margin (pCRM) Involvement in Low Rectal Tumors.

The MERCURY II study demonstrated the use of MRI-based risk factors such as extramural venous invasion (EMVI), tumor location, and circumferential resection margin (CRM) involvement to preoperatively predict pCRM (pathological CRM) outcomes for lower rectal tumors in a mixed group of upfront operated patients and patients who received neoadjuvant treatment. We aim to study the applicability of results of MERCURY II study in a homogeneous cohort of patients who received neoadjuvant chemoradiation (NACTRT) prior to surgery. After Institutional Review Board approval, post NACTRT restaging MRI of 132 patients operated for low rectal cancer between 2014 and 2018 were retrospectively reviewed by two radiologists for site of tumor, EMVI status, distance from anal verge (< 4 or > 4 cm), and mrCRM positivity. Findings were compared with post surgery pCRM outcomes using Fisher's exact test. Only 9/132(7%) patients showed pCRM involvement on histopathology, 8 of them being CRM positive on MRI (p = 0.01). The positive predictive value (PPV) of mrCRM positive status and pCRM status was 12.7% (95% CI: 9.7-16.5%), while the negative predictive value was 98.5% (95% CI: 91.4-99.8%) (p = 0.01). EMVI positive and anteriorly located tumors showed higher incidence of pCRM positivity but were not found to be significant (15% vs 5.2% and p = 0.13 and 8.6% vs 2.1% and p = 0.28, respectively). Unsafe mrCRM was the only factor significantly associated with pCRM positivity on post neoadjuvant restaging MRI. Tumors less than 4 cm from anal verge, anterior tumor location, and mrEMVI positivity did not show statistically significant results to predict pCRM involvement.