Georgetown researchers suggest CyberKnife is viable for pancreatic cancer

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BOSTON—Due to the fact that pancreatic cancer often reoccurs, treatment options are often limited to chemotherapy, but researchers at Georgetown University in Washington, D.C., are utilizing Accuray’s CyberKnife to see if radiosurgery is a viable treatment option in select patients, according to a presentation delivered Sunday at the 50th annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO).

“When treating recurrent pancreatic tumors, there are a number of factors to evaluate before we can consider radiosurgery as an additional treatment option,” said the study’s lead author Christopher Lominska, MD, a resident in radiation medicine at Georgetown's Lombardi Comprehensive Cancer Center. “First, treatment must be safe, which is demonstrated in this study. We also designed a treatment that can be delivered in a short period of time—a critically important quality-of-life factor in this patient population.”

For the study, Lominska and colleagues evaluated the safety of radiosurgery using the Sunnyvale, Calif.-based Accuray’s CyberKnife by reviewing the records of patients treated for pancreatic cancer at Georgetown from June 2002 through July 2007. They treated 28 patients for locally recurrent disease, 20 of whom had had prior chemotherapy and conventional radiation, and eight of whom had had prior surgery, as well as radiation and chemotherapy. They used C or PET/CT imaging to visualize disease recurrence.

The median age of the patients was 63 years old. The researchers followed up with 24 of 28 patients (patients lost to follow-up were assumed deceased). They reported that the median survival from the date of radiosurgery treatment was 5.3 months (range 1-27 months). Seven patients (25 percent) lived more than eight months after treatment, the authors reported.

“We found an acceptable safety profile for those receiving radiosurgery,” Lominska said. “These patients had received full doses of conventional radiation therapy prior to their radiation treatment, so this speaks to the very high level of precision of the CyberKnife— that we were able to give them more radiation safely. It's also worth noting that treatment was delivered in only a week allowing patients to resume systemic chemotherapy with minimal interruption."

Lominska said that only two patients experienced serious gastroenterological toxicity (one peripancreatic abscess, one bowel obstruction) after being treated with three sessions of radiosurgery. Review of radiographic studies revealed local control in six patients, local control with distant progression in six patients and local and distant progression in two patients with no follow-up imaging available on the remaining patients, according to the researchers. By March of this year, 26 of 28 patients had died. The two surviving patients remain locally controlled without evidence of distant disease on follow-up of three and eight months.

He said that preliminary survival trends look good, but are not conclusive until more studies are designed to evaluate if radiosurgery with CyberKnife can extend survival when compared with standard care.

In addition to Lominska, other study authors include Nadim Nasr, MD, Natalie Silver, and Gregory Gagnon, MD; all of Georgetown. The authors reported that Gagnon occasionally serves as a paid consultant and receives speaking fees from Accuray, the manufacturer of the CyberKnife. There was no external funding for the study, the researchers noted.