Study of Low-Dose Fractionated Radiotherapy in Patients With Locally Advanced Metastatic Pancreatic Cancer

People with pancreatic cancer usually have a large amount of the cancer in the area of the pancreas and around it when they are diagnosed with it. Or their cancer has spread (metastasized)outside that area of the abdomen and is not able to be surgically removed (resected). For patients with metastatic disease, one standard treatment is the combination of gemcitabine and erlotinib. This combination has shown slightly longer survival compared to getting gemcitabine alone. For patients with localized but unresectable disease, the standard treatment remains controversial. Early studies showed that chemotherapy and radiation together was better than either one used alone. The greatest benefit of external beam radiotherapy may be after a period of full-dose chemotherapy alone, to help the rapid spread. A problem of beginning treatment with standard radiotherapy is that the doses of chemotherapy usually have to be reduced sometimes by half. Studies have already shown that low dose radiotherapy (LDRT)is safe. This study will evaluate the safety of LDRT instead of standard doses with full dosing of gemcitabine and erlotinib in patients with locally advanced or limited metastatic pancreatic cancer. Patients will be enrolled in groups of 3 to 6 each with a slightly higher dose of LDRT and erlotinib. For patients with locally advanced disease, this protocol also may help because most patients develop and die from spread to the liver and abdominal cavity.