ATP-Based Chemotherapy Response Assay in Patients with Unresectable Gastric Cancer

scribed previously [4] . Tumor tissue was obtained with biopsy forceps during endoscopy. The following drugs were used: 5-fluorouracil, cisplatin, docetaxel, doxorubicin, etoposide, mitomycin, paclitaxel, irinotecan and oxaliplatin. The regimens consisted of two chemotherapeutic agents which have proven to inhibit cancer cell growth most effectively. A total of 24 patients were enrolled between April 2003 and April 2006. Median age was 58 years (range: 33–71 years). Regimens used are summarized in table 1 . The overall response rate was 29.2%. Two cases (8.3%) achieved a complete response. They are still alive without evidence of recurrence 38 and 50 months after six cycles of doxorubicin plus docetaxel and nine cycles of doxorubicin plus cisplatin treatment, respectively. Treatment responses are summarized in table 2 . Median overall survival lasted 6.3 months. Oneand 2year survival rates were 18.5 and 13.9%, respectively. Median time to tumor progression was 3.2 months. Both 1and 2-year progression-free survival rates were 10.6%. In most cases, regimens administered were tolerable. One case of grade 3 neutropenia was noted. In this study, the response rates did not reach the results suggested by ATP-CRA. Since the heterogeneity of tumor cells also Patients with unresectable gastric cancer receive chemotherapy to relieve symptoms and improve survival. However, the susceptibility of individual tumors is expected to be different, and it is highly unlikely to find a universally applicable regimen. The individualized tumor response test (ITRT) has been introduced to help in the selection of the appropriate drug for each individual patient [1] . There are technical differences among the various ITRTs, but they all require a tissue sample of the tumor to be able to process tumor cells and subsequently select the appropriate chemotherapeutic agents following culturing of those cells in vitro. ATP-based ITRT determines the degree of cell inhibition by comparing the ATP remaining in the test compared to the control wells to predict the response to each chemotherapeutic agent. Recently, an ATP-based chemotherapy response assay (ATP-CRA), a modified form of the ATP-based ITRT, has been proven to be useful in lung and breast cancer [2, 3] . Since results can be obtained from a small amount of tissue in a short period of time, the ATP-CRA enables to accelerate treatment initiation to meet clinical requirements. We prospectively conducted a clinical trial of ATP-CRA in unresectable gastric cancer. ATP-CRA was performed as deReceived: November 14, 2007 Accepted after revision: December 3, 2007 Published online: June 3, 2008