C. Jillian Tsai, MD, PhD
A new study from Memorial Sloan Kettering Cancer Center found that high-dose radiation therapy administered alongside systemic therapy in patients with metastatic non-small cell lung cancer can help extend progression free survival. This is the first and largest randomized clinical trial ever to study the use of stereotactic body radiation therapy (SBRT) in treating oligoprogressive metastatic lung and breast cancers. These findings will be presented during this year’s American Society for Radiation Oncology (ASTRO) meeting in Chicago.
In many patients with metastatic lung and breast cancers, a few of their metastatic tumors can become resistant over time to systemic therapies, while others remain stable. Oncologists refer to these isolated growing tumors as oligoprogressive. When this occurs, the common standard approach to care is to switch systemic therapy. Unfortunately, such changes can lead to different side effects, and in some cases, there might not be an option for a different systemic therapy.
“When metastatic cancer is being treated with systemic therapies such as chemotherapy, immunotherapy or hormone therapy, inevitably some tumors will stop responding to treatment,” said C. Jillian Tsai, MD, PhD, MSK radiation oncologist and the study’s lead author. “This setback can be distressing for patients.”
At the time of presentation, the study had accrued 106 MSK patients who were randomized to two study arms: half received SBRT to progressing tumors and the other half were treated with the standard of care, which allowed their physician to change their systemic treatment or continue with their current therapy. All patients had metastatic breast cancer (47) or non-small cell lung cancer (NSCLC) (59) and were noted to have mixed response to their current systemic therapy with between one and five progressing tumor sites. The median follow-up was 45 weeks.
“Interestingly, our interim analysis found that stereotactic radiation is extremely beneficial for lung cancer patients in prolonging their progression-free survival, but unfortunately made no significant difference in patients with advanced breast cancer,” explained Dr. Tsai. For patients with NSCLC treated with SBRT, the median progression-free survival was 44 weeks compared to 9 weeks for those receiving standard treatment. The team noted no difference in progression-free survival among the breast cancer groups (19 weeks with SBRT versus 18 weeks with standard treatment).
SBRT is a targeted radiation treatment that delivers extremely precise, intense doses of radiation to tumor sites while minimizing damage to healthy tissue. It involves the use of sophisticated image guidance that pinpoints the exact three-dimensional location of a tumor so that the radiation can be more precisely delivered. “We utilized SBRT in particular because of its precision and ability to give high-dose radiation focused on tumors,” said Dr. Tsai.
“Our results show that lung cancer patients with oliogoprogressive tumors can obtain a meaningful benefit using this approach,” said Dr. Tsai. “We will continue to look at the important role SBRT plays in these cancers and others, and also work to understand why its effectiveness was not seen across the entire study cohort.”