Shaped-beam radiosurgery treats tiniest lung tumors

Nov 8 2006

Patients with metastatic cancer tumors in their lungs are much more likely to live disease-free if they have an experimental treatment involving shaped-beam radiosurgery rather that conventional treatment, according to a University of Rochester Medical Center study.

The research, presented this week at the American Society of Therapeutic Radiology and Oncology conference in Philadelphia, offers a new option for the tens of thousands of patients annually who must cope with cancer that has spread to their lungs. Usually when the disease advances to that stage, the average survival time is 12 months and treatments are limited. In this study, some patients who were treated more than three years ago still have not had the disease spread.

Shaped-beam, radiosurgery technology was originally designed for destroying brain tumors. Rochester oncologists are expanding its use to other parts of the body, studying whether it can be used to destroy other soft-tissue tumors that were previously considered untreatable. This includes tumors in the liver, adrenal glands and spine.

Last year Paul Okunieff, M.D., and colleague Alan Katz, M.D., reported using the technology to achieve an 88 percent control rate for metastatic tumors in the liver, a result that was considered highly unlikely as recently as five years ago.

The current study was funded in part by BrainLab, the maker of the Novalis radiosurgery system. In the study of 50 patients, 91 percent of the lung tumors treated between February 2001 and December 2005 never progressed, and about 25 percent of patients appear to be disease-free after three years of follow-up.

Doctors hope that shaped-beam radiosurgery and chemotherapy might form a "synergistic combination that allows the drugs to destroy the microscopic cells that imaging studies can't see while the radiation therapy controls the tumors we can see," said Okunieff, chair of Radiation Oncology at the Medical Center's James P. Wilmot Cancer Center.

Perhaps most importantly, this high-dose, focused radiation targets the tumor with very limited damage to healthy tissue that surrounds the lesion, and patients experience minimal side effects even when a large number of tumors are treated, Okunieff said.

"We're getting better and better at finding smaller and smaller tumors that we can irradiate easily, and people are living longer," Okunieff said.

Advances in CT imaging technology are allowing doctors to detect lung cancers earlier, generally improving a person's chance for survival. The new imaging techniques combined with other technologies like Novalis are making it possible for physicians to offer treatments that a few years ago were considered impossible.

"We are now in the process of determining the circumstances in which these new technologies can benefit patients. We seem to have hit on some important ones,' Okunieff said.

Okunieff's current study focused on patients with multiple lung lesions ranging in size from 3 millimeters to 7.7 centimeters between February 2001 and December 2005. Doctors treated 31 people with fewer than five tumors curatively and 19 others with more than five lesions palliatively to slow the disease. These patients had undergone multiple previous therapies for their metastatic disease prior to radiosurgery.

Three years after follow-up, of the 125 lesions treated, 36 lesions (29 percent) disappeared completely, 32 lesions (26 percent) had shrunk, and 49 (39 percent) were stable after treatment. Only eight of the 125 lesions (6 percent) grew larger after the radiosurgery.

"If we can kill the spots that we can see, and they are the most life-threatening, we can help people live longer," Okunieff said. "And when you deliver a one-two punch with chemotherapy to destroy the cancer cells we can't yet see, we dare to consider the potential of controlling metastatic disease comprehensively."