Prognostic value of pre- and post-operative circulating tumor cells detection in colorectal cancer patients treated with curative resection: a prospective cohort study based on ISET device

Background: Circulating tumor cells (CTCs) have been regarded as a promising biomarker for colorectal cancer (CRC); however, the prognostic value of post-operative (op) CTCs is still unclear. This study aimed to compare the recurrence prediction value of pre- and post-op CTCs in CRC patients treated with curative resection. Patients and methods: Consecutive CRC patients treated with curative resection from January 2014 to March 2015 were identified. CTCs from 2.5 mL peripheral blood were enumerated with an ISET device-CTCBIOPSY (R) before and after surgery. Based on the status of pre- and post-op CTCs, the included patients were grouped into four cohorts: pre- and post-op CTCs-, pre-op CTCs- but post-op CTCs+, pre-op CTCs+ but post-op CTCs-, and pre- and post-op CTCs+. The 3-year recurrence-free survival (RFS) rate of patients was analyzed. Results: A total of 138 patients (79 [57.2%] male; median ag e= 62 [43-75] years) were enrolled. Patients with pre-op CTCs- had a 19.2% higher 3-year RFS rate (86.2%) than the combined cohorts with pre-op CTCs+ (67.0%) (P=0.038). Patients with post-op CTCs+ had as 25.6% lower 3-year RFS rate (57.1%) than the combined cohorts with post-op CTCs- (82.7%) (P=0.001). Moreover, patients with pre- and post-op CTCs+ had a 25.1% lower 3-year RFS rate (53.8%) than patients with pre-op CTCs+ but post-op CTCs- (78.9%) (P=0.004). Multivariate analyses confirmed that post-op CTCs+ (I IR=2.82, 95% CI=1.39 5.75, P=0.004), but not but pre-op CTCs+ (HR=2.17, 95% CI=0.75-6.31, P=0.153), was independently associated with shorter 3-year RFS rate. Conclusion: Post-op CTCs+, but not pre-op CTCs+, is an independent indicator of poor prognosis for CRC patients treated with curative resection. Patients with post-op CTCs+ have a higher risk of recurrence those with pre-op CTCs+. Evaluation of post-op, rather than pre-op, CTCs is warranted.