In achieving local control within patients with pancreatic neuroendocrine tumors (PNT), radiation therapy (RT) is a an effective treatment, according to a study published Nov. 15 in the International Journal of Radiation Oncology*Biology*Physics.
Joseph N. Contessa MD, PhD, and colleagues from the department of radiation oncology at the University of Michigan Medical Center in Ann Arbor, proposed that PNTs may not be as resistant to RT as previously suggested.
According to the authors, PNTs are rare, malignant neoplasms about which there are few clinical studies. This cancer can stay confined to the liver and often lead to liver damage, resulting in death. It is typically unable to be removed by surgery; therefore, the authors sought to determine if external beam radiation therapy (EBRT) could help manage the condition and extend the life expectancy of the diagnosed patient.
The researchers analyzed records of 36 patients presenting with PNTs, who had been treated with RT at 49 sites between 1986 and 2006. In 39 percent of patients, it was found that the tumor shrunk to less than half of its pretreatment size after undergoing EBRT treatment (13 percent complete response, 26 percent partial response). In the remaining patients who underwent RT, 56 percent experienced stable disease and 4 percent experienced disease progression.
Additionally, the authors said that 90 percent of patients saw palliation of symptoms, such as pain, nausea, vomiting or obstructive jaundice, and the three-year local freedom from progression rate was 49 percent.
Of the 36 patients, 23 had radiographic follow-up data that was used to determine the tumor response rate and freedom from local progression.
The authors determined that 33 patients had metastatic disease at their referral for RT, and the median overall survival for this patient population was two years. They recorded three long-term Grade 3 or greater toxicities, based on the National Cancer Institute Common Terminology Criteria for Adverse Events.
"While this particular type of cancer can have potentially devastating effects on a patient, this study proves that using external beam radiation therapy may permit these patients to live longer, which is a very positive breakthrough for a disease that can have very negative outcomes," said co-author Theodore S. Lawrence, MD, PhD, chair of the department of radiation oncology at the University of Michigan.