Radiological Surveillance Post-Curative Colorectal Cancer Resection: Is There a Need for a Targeted Protocol?

Background The frequency of radiological surveillance after curative colorectal cancer resection has long been a controversial issue with the need to balance potential harm from ionizing radiation and the financial burden of intense surveillance against advantages of early detection of recurrent disease. NICE guidelines issued in 2018 suggested having two surveillance computed tomography (CT) scans within three years of surgery without specifying the timing or the interval. Aim To examine whether an evidence-based flexible approach based on individual patients' risk factors can add value to surveillance protocols. Reaching a targeted protocol that can maximize early detection of metastasis without consumption of resources and most important without compromising patient safety. Methodology A retrospective study involving five years of data of patients who underwent curative colorectal cancer resections. Data extracted after patients completed their three-year surveillance CT scans, CT reports retrieved together with post-operative histology reports, and a detailed database was constructed. Results Of 179 patients included, 66 developed recurrence (7 local and 59 distant). Recurrence increased from 23.5% in T1 to 66% in T4 (P=0.0001). The median time to recurrence 23 months in T4 disease compared to 36, 42 and 43 months for stages T1, T2 and T3, respectively (P=0.0001). A similar incremental increase in recurrence noted from 22% in the N0 stage to 73.5% in the N2 stage (P=0.0001); the median time to recurrence of 14 months in N2 patients compared to 45 and 33 months for stages N0 and N1, respectively (P=0.0001). Recurrence correlated well with positive extramural vascular invasion (EMVI) status, (71.7% versus 19.3% P=0.0001) being detected significantly earlier in EMVI positive group at 17 versus 45 months (P=0.0001). Conclusion Flexible protocol for radiological surveillance after curative resection of colorectal cancer, based on known pathological prognostic factors, is likely to be more effective in maximizing resource utilization as well as improving patient outcomes.