Carcinoembryonic antigen directed PET-CECT scanning for postoperative surveillance of colorectal cancer.

AIM: During the follow-up of surgically resected colorectal cancer (CRC), positron emission tomography-contrast-enhanced computed tomography (PET-CECT) is indicated for asymptomatic elevation of carcinoembryonic antigen (CEA) > 5 ng/ml and no obvious site of recurrence on clinical examination and basic imaging. As an institutional policy, a PET-CECT scan was performed at our institute whenever (1) CEA levels rose above 5 ng/ml and (2) CEA values were doubled (even if the CEA level was < 5 ng/ml). Our aim was to correlate the range of CEA elevation with recurrence rates and to evaluate the diagnostic utility of PET-CECT scanning in this setting. METHOD: We retrospectively analysed all cases where a PET-CECT scan was performed for elevated CEA levels during surveillance visits after complete resection of the primary tumour followed by adjuvant therapy. This study was conducted from 1 January 2013 to 31 July 2015. RESULTS: In all, 104 patients underwent a PET-CECT scan for rising CEA values, and 62 patients (59.6%) were found to have recurrent disease. At CEA levels < 5, 5.1-10, 10.1-15, 15.1-50 and > 50 ng/ml, disease recurred in 10%, 45%, 70%, 94% and 100% patients, respectively. Sensitivity, specificity, positive predictive value and negative predictive value of the PET-CECT scan were 92.7%, 95.2%, 96.2% and 90.9%, respectively. Elevation of CEA levels during follow-up was indicative of recurrence in 68% of the secretors and 45% of the non-secretors (based on baseline CEA status). CONCLUSION: In the setting of rising CEA levels during follow-up of patients with CRC, a PET-CECT scan is a valuable tool to detect recurrence, irrespective of the baseline CEA secretor status. The likelihood of recurrence of disease was directly proportional to the value of the raised CEA level.

High nodal positivity rates even in good clinical responders after chemoradiation of rectal cancer: is organ preservation feasible?

AIM: Local excision (LE) is emerging as a treatment option for rectal cancer responding well to chemoradiation. However, it does not address the mesorectal nodal burden. We aimed to identify the factors influencing nodal positivity and subsequently defined a low-risk group by including only patients at low risk. METHOD: A single-centre, retrospective database analysis was carried out of patients with radically resected rectal cancer after neoadjuvant chemoradiation. RESULTS: This study included 524 patients with predominantly low rectal tumours. Nodal positivity among ypT0, T1 and T2 groups was 14.7%, 28% and 30%, respectively. Multivariate analysis with stepwise logistic regression identified the following low-risk features: age ≥ 40 years, nonsignet ring cell carcinoma (SRCC) histology and pathological complete response (pCR). Sixty-nine patients fulfilling all three criteria were analysed and the nodal positivity was found to be 10.1%, which implies that, if these patients had been selected for LE, one in 10 would have had positive mesorectal nodes. CONCLUSION: Even in patients with low-risk criteria (pCR, non-SRCC histology and age ≥ 40 years), the residual positive nodal disease burden is 10%. Whether this high incidence of residual nodal disease translates into a similar risk of locoregional recurrence if an organ-preservation strategy is adopted is unclear.