Identifying an early indicator of drug efficacy in patients with metastatic colorectal cancer-a prospective evaluation of circulating tumor cells, 18F-fluorodeoxyglucose positron-emission tomography and the RECIST criteria

B. Ma, A. D. King, L. Leung, K. Wang, A. Poon, W. M. Ho, F. Mo, C. M.L. Chan, A. T.C. Chan, Sze Chuen Cesar Wong

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14 Citations (Scopus)


Background: This study investigated the predictive and prognostic significance of assessing early drug response with both positron-emission computerized tomography (PET-CT) and circulating tumor cells (CTCs) in patients receiving first-line chemotherapy for metastatic colorectal cancer. Patients and methods: Eligible patients had PET-CT and CTC analysis at baseline and 4-6 weeks after starting chemotherapy, and then a CT scan at 10-12 weeks to assess the Response Evaluation Criteria In Solid Tumors (RECIST) response. Early response was defined as achieving a dual-endpoint consisting of PET-CT (30% drop in the sum of maximum standard uptake values- SUVmax-of target lesions) and CTC response (CTC<3 cells/7.5 ml blood) at 4-6 weeks after starting chemotherapy. Results: About 84 patients were enrolled with a median follow-up of 32.9months (95% confidence interval, CI, 24.5months-not reached, NR), and 70 patients (84.3%) completed all assessments. Achieving an early response based on the dual-endpoint was independently associated with progression-free survival (hazard ratio, HR=0.452, 95% CI 0.267-0.765). The median progression-free survival of early responders was 7.41months (95% CI, 6.05-9.11) compared with 5.37 months (95% CI, 4.68-6.24) in non-responders (log-rank, P=0.0167). RECIST response at 10 weeks was independently associated with overall survival (OS) (HR=0.484, 95% CI, 0.275-0.852). Early response based on the dual-endpoint could predict the subsequent RECIST response with a sensitivity, specificity and positive predictive value of 64%, 70% and 74%, respectively. Conclusions: Early response based on both PET-CT and CTC analysis has prognostic and probably predictive significance in patients undergoing first-line chemotherapy for metastatic colorectal cancer. Its utility as a new tool for assessing early drug response should be further validated.
Original languageEnglish
Pages (from-to)1576-1581
Number of pages6
JournalAnnals of Oncology
Issue number7
Publication statusPublished - 30 Mar 2017


  • Circulating tumor cells
  • Colorectal cancer
  • Positron-emission tomography

ASJC Scopus subject areas

  • Hematology
  • Oncology

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