Weekly paclitaxel as a radiation sensitizer for locally advanced gastric and pancreatic cancers: the Brown University Oncology Group experience.

Many patients with cancer of the stomach or pancreas have locally advanced, unresectable disease at diagnosis or will develop an early local or regional recurrence despite potentially curative surgery. Effective local treatment could increase the proportion of patients able to undergo surgery and decrease locoregional recurrences, which should improve overall survival. External beam radiation (RT) by itself has little effect. Standard treatment, such as RT with concurrent administration of 5-fluorouracil-based chemotherapy as a radiation sensitizer, has, at best, a modest impact on locoregional recurrences and survival. The use of a more effective radiosensitizer might improve the efficacy of local treatment. Paclitaxel synchronizes cells at G2M, the phase of the cell cycle during which cells are most sensitive to the effects of ionizing radiation, and has been demonstrated to sensitize a variety of human cell lines to the effects of RT. In patients with locally advanced non-small cell lung cancer (NSCLC), the Brown University Oncology Group (BrUOG) has demonstrated a high response rate to low-dose weekly paclitaxel with concurrent RT. In addition, we demonstrated that the response to paclitaxel/RT was not affected by mutations in the p53 tumor suppressor gene. This suggested that paclitaxel/RT would be a rational treatment approach for other malignancies with a high frequency of p53 mutations, such as gastric and pancreatic cancers. We have completed a phase I study of weekly paclitaxel and concurrent radiation for locally advanced gastric and pancreatic cancers. The maximum tolerated dose of paclitaxel was 50mg/m2/week for six weeks with 50 Gray (Gy) abdominal radiation. The dose limiting toxicities were abdominal pain, nausea and anorexia. Preliminary response data from ongoing phase II studies suggest that preoperative paclitaxel/RT has substantial activity in patients with locally advanced gastric and pancreatic cancers, though whether this will translate into improved disease-free and overall survival in these patients is not known.