Long-term prognostic value of detection of circulating colorectal cancer cells using CGM2 reverse transcriptase-polymerase chain reaction assay

BackgroundThe criteria commonly used for prognosis of colorectal cancer remain histoprognostic and are based on primarily TNM classification. The lack of discrimination of purely histoprognostic criteria is evidenced by the development of different outcomes in similarly staged patients. The aim of this work was to study the long-term prognostic value of preoperative detection of circulating enterocytes in the blood of colorectal cancer patients using the CGM2 reverse transcriptase-polymerase chain reaction (RT-PCR) assay.MethodsA nested RT-PCR with specific primers for CGM2 was used preoperatively to detect circulating enterocytes in 121 patients (64 men, 57 women; mean age, 70 years) with colorectal neoplasms.ResultsCirculating enterocytes were detected in 58/121 (48%) patients. The positivity rate was not correlated with American Joint Committee on Cancer (AJCC) staging (stage I, 11/28 (39%); stage II, 13/34 (38%); stage III, 15/23 (65%); stage IV, 17/32 (53%); sterilized (after radiotherapy, no residual neoplasm) 2/4 (50%); not significant [NS]), but circulating enterocytes were detected more frequently in patients with metastatic lymph nodes (60% vs 41%, P = .06). Overall 5-year survival rates (mean ± SD) were 40 ± 13% and 45 ± 13% for patients without and with circulating enterocytes, respectively (P = NS). Similarly, recurrence-free survival rates were 71 ± 4% versus 72 ± 14% (P = NS). Using univariate analysis, AJCC stage (P < .0001) was correlated with survival. AJCC stage (P = .007) and obstructive neoplasms (P = .043) were correlated with recurrence-free survival. Using multivariate analysis, AJCC stage was correlated with survival and recurrence-free survival.ConclusionsPreoperative detection of circulating enterocytes using CGM2 RT-PCR assay provides no specific prognostic information and cannot be used as a decision criterion for adjuvant therapy.