Frank Lagerwaard, MD, radiation oncologist at VU University Medical Center in Amsterdam, reported this week in a presentation that patients with Stage I NSCLC who were treated with stereotactic ablative radiotherapy (SABR or SBRT) and who were potentially suitable for an operation, achieved similar tumor control rates to individuals treated with the current surgical standard of care. 33% of participants in the investigation were treated with Varian Medical System’s RapidArc delivered on a Novalis TX liner accelerator from Varian and Brainlab.
` Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, it is considered Stage I when the tumor is small and has not yet spread to further areas within the body or to nearby lymph nodes. Surgery that involves removing a small section of the affected lung is usually the standard of care. Complications of this surgery can include, wound infections, chest wall pain, atrial fibrillation and pneumonia.
Dr. Lagerwaard, chief study author, explained:
“Based on the results of our analysis, SABR appears to be an important option to be considered by all patients presenting with early-state lung cancer. These data also support ongoing randomized clinical trials comparing surgery and SABR in potentially operable stage I NSCLC.”
SABR involves treating the tumor with a high dose of targeted radiation. Radiation is used to kill cancer cells by damaging their DNA. Complications of treating lung cancer with SABR may include, chest wall complications (pain, chest wall swelling, rib fractures), radiation-induced pneumonitis, finding it hard to breath, cough, and feeling fatigued.
Lagerwaard and his team looked through records of individuals with lung cancer treated between the years 2003 to 2010, to find those who could have been candidates for surgery, based on their overall health and tumor characteristics, but who received SABR instead. In the investigation a total of 177 patients (76 women and 101 men) were examined.
Medical records revealed that three years after treatment 93% of patients treated with SABR included in the investigation did not show local tumor regrowth. This is similar to prior outcomes reported for individuals who received NSCLC surgery.
For the operable patients who received SABR the average overall survival (OS) was 61.5 months, survival rates for one year was 94.7%, for three year 84.7% and for five year 51.3%. For those who received SABR the thirty-day mortality was 0%. This was promising compared to a previous report by other investigators that predicted that 2.6% of patients undergoing a lobectomy (removal of the affected lobe of the lung), would die within 30 days (based on the Thorascore model, Falcoz PE, 2007).
In the investigation 42% of patients reported no early adverse effects with the SABR treatments. Participants who report early adverse effects experiences cough (14%), fatigue (25%), dyspnea (10%) and local chest wall pain (11%), some participants reported more than one adverse effect. Late SABR adverse effects involved radiation pneumonitis for which 2% of patients needed medication, and rib fractures in 3% of patients.
In an additional presentation, Jeffrey Bradley, M.D., associate professor of radiation oncology at Washington University in St. Louis summarized primary results from a prospective Phase I/II investigation to find out the ideal dose of SBRT for NSCLC located in the central part of the lung, near the bronchial tree (main airway). 24 patients with Stage 1 NSCLC participated in the investigation.
According to Dr. Bradly, a previous investigation of SBRT for NSCLC did not identify the difference between tumors that were central or peripheral. Individuals with both types of tumor were enrolled to participate in a prospective dose-escalation investigation that began by giving each patient three treatments of 8 Gray (a unit of dose) and increased up to 24 Gray at each of three treatments.
Dr. Bradley explained:
“From that experience, the investigators described excessive toxicity for tumors located within 2 centimeters of the proximal bronchial tree and warned of potential toxicity. Based on the report, we launched this prospective Phase I/II study in an effort to help determine a viable treatment protocol for centrally located early-stage lung cancers. The Radiation Therapy Oncology Group (RTOG)* followed along and also has a prospective dose escalation study ongoing for this population.”
Each participant in the investigation received five SBRT Treatments. 5 participants received a dose of 9 Gray units per treatment, 6 participants received 10 Gy per treatment, 6 participants received 11 Gy per treatment, and 5 received 12 Gy per treatment. Overall, the main tumor control rate was 95.5%. Out of the 24 participants 16 remain alive and have a project OS rate of 45.7%, a projection that is based on the published data on this medically inoperable group (7,8). Toxicities from treatment stayed tolerable at doses of up to 12 Gy, only one participant developed a grade 3 pneumonitis. The study will proceed to Phase II in order to measure how effective a dose level of 5-11 Gy is.
Dr. Bradley said:
“To date, local tumor control has been excellent for patients in this trial. This study, along with others, will help determine a viable SBRT treatment protocol for centrally-located early-stage lung cancer, which could provide a treatment option for patients with this inoperable disease.”
Dow Wilson, Varian’s chief operating officer, explained:
“The findings from these two studies show the importance of continuing to evaluate new treatments for lung cancer. Advancements in radiotherapy have the potential to help treat early-stage lung cancer without some of the complications of surgery, and they appear to offer inoperable patients a viable treatment option.”
*The RTOG is a national clinical cooperative group funded by the National Cancer Institute in order to carry out cancer treatment research.
Written by Grace Rattue