In North America, the Radiation Therapy Oncology Group (RTOG) conducted a study (RTOG-9704) of pancreatic cancer patients postresection who were randomly assigned to receive either gemcitabine followed by 5-FU and radiation followed by gemcitabine or 5-FU followed by 5-FU and radiation followed by 5-FU. The two treatment arms differed on the systemic therapy components. The study reported superior survival in patients with pancreatic head tumors treated with the gemcitabine-based regimen (20.5 months vs. 16.9 months, hazard ratio, 0.82; P=0.09) (JAMA 2008;299:1019). More recently, Japanese researchers reported the preliminary results of their trial using S1 or gemcitabine as adjuvant therapy in the pancreatic cancer at the 2013 American Society of Clinical Oncology (ASCO) meeting, and so far, the survival benefit in this trial has surpassed all previous adjuvant studies with a 2-year survival rate of 70% in the S1 arm and 53% in the gemcitabine arm. Currently, S1 is available only in Asia.
B. Borderline resectable and locally advanced pancreatic cancer. Borderline resectable disease is an emerging entity. It is distinguished from locally advanced disease by having less involvement of the tumor vasculature. For example, if the tumor abuts the superior mesentery artery (SMA), it is considered borderline resectable because there is still a chance for resection, despite the fact that the risk for a positive margin is high. If the tumor encases the SMA, then it is considered locally advanced because the chance of resection with a clean margin is zero; so by definition, patients with locally advanced disease are not candidates for curative resection. The detailed radiographic differences of vascular involvement between borderline resectable and locally advanced pancreatic cancer can be found on the National Comprehensive Cancer Network (www.nccn.org).
Because of the 70% distant recurrent rate in patients who undergo curative resection, it is logical to consider systemic therapy prior to surgery. The rationales for exploring this approach include identifying patients with rapidly progressive disease so that they may avoid an unnecessary operation, eliminating micrometastases, improving the effectiveness of RT (because surgery may interfere with the effectiveness of postoperative RT as a result of vascular damage from surgery), and downstaging tumors to decrease the risk of positive surgical margins. This upfront systemic therapy approach to managing borderline resectable pancreatic cancer is gaining acceptance in the oncology community. Although the optimal upfront therapy remains undefined, aggressive chemotherapy regimens with proven survival benefits in the metastatic setting, such as 5FU, oxaliplatin, irinotecan (FOLFIRINOX), or gemcitabine and nab-paclitaxel, have been extrapolated to this setting. Concurrent chemotherapy and RT has also been used in this setting.
The standard treatment for patients with locally advanced pancreatic cancer is systemic chemotherapy. The benefit of concurrent chemotherapy and RT in this setting was initially reported in the Groupe Cooperateur Multidisciplinaire en Oncologie (GERCOR) study (J Clin Oncol
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