for Pancreatic Cancer
Radiation therapy or radiotherapy uses high-energy rays to damage or kill cancer cells by preventing them from growing and dividing. Similar to surgery, radiation therapy is a local treatment used to eliminate or eradicate visible tumor. Radiation therapy is not typically useful in eradicating cancer cells that have already spread to other parts of the body. Radiation therapy may be externally or internally delivered. External radiation delivers high-energy rays directly to the cancer site from a machine outside the body. Internal radiation, or brachytherapy, involves the implantation of a small amount of radioactive material in or near the cancer.
The role of radiation therapy alone for the treatment of pancreatic cancer is limited. Radiation therapy is usually given in combination with chemotherapy for treatment of stage I, II or III cancer, which can improve the average duration of survival for patients with localized and locally advanced disease.1
External Beam Radiation Therapy
Radiation therapy is delivered to the pancreas and surrounding lymph nodes from a machine outside the body, called a linear accelerator, or from a shielded repository of a powerful isotope, such as cobalt 60. External beam radiation therapy is most often administered in conjunction with chemotherapy. In some instances, patients with advanced disease are treated with radiation therapy alone for palliation. Conventional radiation therapy is administered over a course of 5-7 weeks. The Radiation Therapy Oncology Group (RTOG) is actively involved in improving radiotherapy techniques for pancreatic cancer. The RTOG has evaluated higher dose radiation delivered on a twice-a-day basis as well as low-dose liver irradiation in clinical trials. Definite improvement with these approaches awaits results of further study. Technical advances in treatment planning of radiation therapy are allowing more precise targeting of radiation to the cancer.
Three-dimensional conformal radiation therapy can precisely target radiation to the areas of where cancer cells may be located, and therefore minimize side effects from radiation to normal structures such as the liver, stomach and kidneys. Because many patients develop areas of cancer cells in the liver, low-dose radiation therapy aimed at the entire liver has been used in an attempt to destroy cancer cells.
Intraoperative Radiation Therapy (IORT): Intraoperative radiation therapy (IORT) is a single dose of radiation therapy that is delivered directly to the area of surgery during the operation. IORT is performed in specially-equipped operating rooms. During IORT, the radiation doctor can see the area being treated and move sensitive normal structures, such as the small bowel, away from the radiation beam. Results from some studies evaluating IORT indicate that cancer may recur less often in the area of the surgery.
Three-dimensional Conformal Radiation Therapy: Three-dimensional conformal radiation therapy can precisely target radiation to the areas where cancer cells may be located and therefore, minimize side effects from radiation to normal structures such as the liver, stomach and kidneys. Because many patients develop areas of cancer cells in the liver, low-dose radiation therapy aimed at the entire liver has been used in an attempt to destroy cancer cells.
Side Effects of Radiation Therapy
Although patients do not feel anything while they are receiving radiation treatment, the effects of radiation gradually build up over time. Many patients experience fatigue as treatment continues. Loose stools or diarrhea is also common.
1 Hazard L, Tward JD, Szabo A, Shrieve DC. Radiation therapy is associated with improved survival in patients with pancreatic adenocarcinoma: results of a study from the Surveillance, Epidemiology, and End Results (SEER) registry data. Cancer. 2007;110:2191-201.