Dynamic monitoring of circulating tumour cells to evaluate therapeutic efficacy in advanced gastric cancer

BACKGROUND: This study was intended to determine the clinical significance of circulating tumour cells (CTCs) in patients with advanced gastric cancer (AGC), particularly the potential role of CTCs for dynamic monitoring of the therapeutic response. METHODS: A single-centre, prospective study was undertaken in 136 patients with newly diagnosed AGC. The patients' CTCs were enumerated using CellSearch at baseline and at the first response evaluation. In 15 patients whose clinical condition permitted longitudinal study, CTCs were longitudinally enumerated during treatment. RESULTS: Following 6 weeks of chemotherapy, an unfavourable post-therapy CTC level (⩾3 CTCs per 7.5 ml) was closely correlated with the objective response rate (P=0.016) and the disease control rate (P=0.013), and it also independently predicted a shorter progression-free survival and overall survival. Particularly, conversion to a favourable CTC level following therapy improved the prognosis, but patients who changed to an unfavourable CTC level fared significantly worse. Elevated CTCs during therapy may be associated with a poor prognosis. CONCLUSIONS: Post-therapy CTC level may help in evaluating therapeutic response in patients with AGC and predicting their prognosis. In addition, changes in CTCs following therapy may be useful in rapidly identifying ineffective treatments and poor prognosis.