SBRT, CRT Radiation Therapies May Not Have Many Differences for NSCLC

Radiation therapy techniques, including stereotactic body radiotherapy (SBRT) and hypofractionated conventional radiotherapy (CRT), had no detected differences for patients with peripheral and central stage 1 non-small cell lung cancer (NSCLC).

Findings from the phase 3 LUSTRE study, published in JAMA Network, compared SBRT and hypofractionated CRT by evaluating a total of 233 patients who were randomly assigned to receive SBRT or CRT. The SBRT group included 154 patients and the CRT group included 79 patients.

A total of 64 patients had centralized tumors, which included 45 patients in the SBRT group and 19 in the CRT group, according to the study.

SBRT Versus Hypofractionated CRT for NSCLC

SBRT is a type of radiation therapy that delivers beams of energy to targeted areas of the body where tumors are present, as defined by the Mayo Clinic.

“Historically, radiation therapy for [patients with] lung cancer has taken several weeks to complete and required low doses of radiation given over multiple sessions — sometimes 30 or more treatments,” added Dr. Bismarck C. Odei in an email interview with CURE®. “SBRT, on the other hand, allows for a dramatic shortening of the treatment duration by delivering very high doses of radiation in a safe and highly precise way. This precision targets the tumor while sparing healthy tissue, and treatments are typically completed in five or fewer sessions.”

Odei is a physician-scientist and assistant professor of genitourinary cancers in the Department of Radiation Oncology at Huntsman Cancer Institute at the University of Utah.

Similarly, he explained that hypofractionated CRT also delivers high doses of radiation, but the duration of radiation is shorter than traditional radiation therapy and requires more sessions than SBRT.

“You can think of it as a middle ground between the traditional long-course treatments and the shorter SBRT approach,” Odei said. “In the LUSTRE trial, hypofractionated radiotherapy required 15 treatment sessions.”

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Although the study did not find significant differences between the two radiation techniques, Odei noted that there are still some differences.

“They differ in several ways. SBRT delivers higher doses of radiation per treatment compared to hypofractionated radiotherapy. SBRT also requires fewer days to complete the treatment course, often five or fewer sessions, while hypofractionated radiotherapy may require around 15 sessions,” he explained. “Additionally, when treating tumors near vital organs in the chest, SBRT may have a higher risk of [side effects] due to the higher dose per session. With either type of treatment, care is taken to ensure that the radiation is delivered safely, considering the patient's breathing and how it might affect the location of the cancer being targeted.”

Why There Aren’t Many Differences Between SBRT and Hypofractionated CRT

In the study, a total of 34 local control events were observed in the patient population, with 18 in patients from the SBRT group and 16 in the CRT group. The three-year local control with SBRT was 87.6% versus 81.2% with CRT.

“The LUSTRE trial found that both SBRT and hypofractionated radiotherapy had similar effectiveness in controlling the cancer and had low rates of severe side effects. This might be because hypofractionated radiotherapy, by using larger doses per session than traditional radiotherapy, can be almost as effective as SBRT,” Odei said. “Additionally, advancements in radiation technology have improved the precision and effectiveness of both treatments. As a result, the difference in outcomes between the two methods may not be as significant as previously thought. However, we need more research to fully understand the differences between these two treatment approaches because the LUSTRE trial had some limitations.”

An important limitation of note was that the study had fewer patients than originally planned, Odei explained.

“A smaller sample size makes it harder to see clear differences between the treatments,” he said. “Also, more than half of the patients couldn't have a biopsy to confirm their cancer because of health risks. Without biopsy confirmation, there's a chance that some patients didn't actually have cancer, which could influence the study outcomes.”

According to Odei, the hypofractionated CRT used in the study worked better than what was anticipated.

“This could be due to improvements in technology and techniques since earlier studies,” he explained. “Because the hypofractionated radiation treatment did so well, it affected the criteria the researchers had planned to use to determine which treatment type was better.

Because of these limitations, we hope future studies will build on what the LUSTRE researchers did to deepen our understanding of these treatment approaches.”

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