Reproduction of Gastric Cancer Prognostic Score by real-time quantitative polymerase chain reaction assay in an independent cohort

Purpose Addition of molecular markers to the American Joint Committee on Cancer (AJCC) staging system would allow further refinements in predicting recurrence and help individualize treatment decisions. We aimed to validate the Gastric Cancer Prognostic Score (GCPS) in an independent cohort using an easy and cost effective quantitative real-time polymerase chain reaction (qRT-PCR) assay. Methods We performed qRT-PCR using 48 samples from our previous study and expanded to 128 independent patients. The GCPS was recalculated using Cox regression estimates and the performance of cutoff values for GCPS was reassessed. Results The qRT-PCR results showed a similar pattern to nanostring data by scale function data comparison. Using a new cutoff value, GCPS stratified 95 stage IB–III patients who received adjuvant chemotherapy into 74 high-risk patients and 21 low-risk patients with significantly different recurrence-free survival (P< 0.0001). The survival difference remained significant (P= 0.028) in 27 patients who did not receive adjuvant chemotherapy. Among stage I and II patients who were treated with surgery only, one AJCC stage IIA patient was defined as low-risk and showed long-term survival. Nine of 12 high-risk patients showed recurrence less than 67 months after operation. Conclusion We reproduced the GCPS with an easily applicable qRT-PCR assay and successfully predicted recurrence in patients with gastric cancer.