Radiation oncologists could play a key role in treating widespread bone metastases even in the absence of symptoms, according to research presented at the American Society for Radiation Oncology (ASTRO) annual meeting in San Antonio.
Dr. Erin Gillespie.A phase II multicenter randomized clinical trial showed that treating high-risk, asymptomatic bone metastases with radiation may reduce painful complications and hospitalizations, as well as possibly extend overall survival in people whose cancer has spread to multiple sites. Traditionally, palliative radiation has focused on reducing existing pain and other symptoms when a patient's cancer is no longer considered curable.
"It's thought-provoking that radiation to prevent pain could potentially prolong life," said Dr. Erin F. Gillespie, lead author of the study and a radiation oncologist at Memorial Sloan Kettering Cancer Center in New York, in a statement from ASTRO. "It suggests that treating to cure the cancer is not the only thing that can help people live longer."
Many patients hospitalized for painful bone metastases have evidence of these lesions on imaging scans several months earlier. External beam radiation therapy is standard-of-care for painful lesions, but it has not been used for asymptomatic ones outside of the oligometastatic setting; generally, patients remain on systemic therapy until lesions become symptomatic.
Dr. Gillespie and colleagues sought to determine "if and when we might intervene before these symptoms occur to prevent hospitalizations and debility from cancer."
The researchers enrolled 78 adults with a metastatic solid tumor malignancy and more than five metastatic lesions, including at least one asymptomatic high-risk bone lesion. The subjects had a cumulative 122 bone metastases.
The most common types of primary cancer were lung (27%), breast (24%), and prostate (22%).
Participants were randomly assigned to receive standard treatment, which could include systemic treatment (such as chemotherapy or targeted agents) or observation, with or without radiation therapy to treat all of their high-risk bone metastases.
The primary endpoint was to determine whether treating asymptomatic lesions could prevent skeletal-related events, which are often a painful and debilitating complication of bone metastases that can contribute to a higher risk of death.
Treating the asymptomatic lesions with radiation reduced the number of these events and related hospitalizations, as well as extended overall survival, compared to people who received no radiation.
At the end of one year, for patients on the radiation arm, skeletal-related events occurred in one of 62 lesions (1.6%), compared with14 of 49 lesions (29%) for those receiving standard care (p < 0.001). Significantly fewer patients in the radiation arm were hospitalized for skeletal-related events (0 vs. 4, p = 0.045).
After a median of 2.4 years of follow-up, overall survival was significantly longer for patients who received radiation therapy, compared to those who did not (hazard ratio 0.50, 95% confidence interval 0.28-0.91, p = 0.02).
After the first three months, patients in the radiation arm reported less pain than those in the standard care arm (p < 0.05), a trend that continued but was no longer statistically significant for the remainder of the study.
"Our trial results add to a growing field of study examining the potential of early supportive care, but they still need to be confirmed in a larger phase III trial," Gillespie said.
