Lung cancer patients with underlying idiopathic pulmonary fibrosis (IPF) treated with proton radiation therapy live longer than those treated with X-ray irradiation, a study shows.
Additionally, fewer occurrences of treatment-related lung complications were reported in proton therapy-treated patients.
The study, “Preliminary result of definitive radiotherapy in patients with non-small cell lung cancer who have underlying idiopathic pulmonary fibrosis: comparison between X-ray and proton therapy,” was published in the journal Radiation Oncology.
IPF in patients with early-stage non-small cell lung cancer (NSCLC) can increase the chances of pulmonary complications following radiation therapy to treat cancer.
X-ray therapy and proton therapy are two radiation therapy techniques. Proton therapy has been shown to be safe in IPF patients. However, studies comparing the overall safety of the two treatments in NSCLC patients with IPF are limited.
To address this, researchers at Samsung Medical Center, Sungkyunkwan University School of Medicine in Seoul, South Korea, reviewed the medical records of NSCLC patients with underlying IPF to compare the impact of X-ray and proton radiation therapy on overall survival.
They identified 264 early-stage (I and II) NSCLC patients who received radiation treatment at the Samsung Medical Center between January 2010 and October 2017.
Of these patients, the medical records of 30 patients with underlying IPF were analyzed. The median age of these patients was 76 years, and the median follow-up period was 11 months.
Among the 30 patients, 22 received X-ray and eight were treated with proton radiation therapy.
Four treatment-related deaths occurred only in the group treated with X-ray therapy, accounting for 18.2% of the 22 patients.
Results showed that proton therapy improved overall survival compared with X-ray. All patients who received proton therapy were alive six months after treatment, representing the six-month overall survival rate, compared with 67.9% of those treated with X-ray therapy.
Similarly, the one-year overall survival rate was 66.7% for patients on proton therapy, and 46.4% for those who received X-ray radiation therapy.
IPF stages are classified as GAP stages based on age, sex, and lung function status. There are three GAP stages — the higher the stage, the more severe is the condition and poorer the prognosis. Results showed that patients in GAP stages II and III who received proton therapy had a significantly better one-year overall survival rate (50%) than X-ray patients (26.4%).
Treatment-related pulmonary complications occurred more frequently in the X-ray group (40.9%), than in the proton radiation therapy group (12.5%), although this difference was not considered statistically significant.
Researchers noted that regardless of the type of radiation therapy used, treatment-related pulmonary complications proved fatal in most patients within one month of symptom onset.
“[Radiation therapy] is associated with serious treatment-related complications in patients with IPF,” but “proton therapy may be helpful to reduce these acute and fatal complications,” the researchers concluded.
One of the limitations of the study is the small number of patients assessed; therefore, future studies with a larger sample size are needed.
The Samsung Medical Center is currently conducting a Phase 2 trial in patients with IPF and/or severely compromised pulmonary function.
“We hope our ongoing prospective study with a large number of patients and systematic evaluation of pre- and post-treatment lung functions could confirm the benefit of proton therapy for patients with severely compromised pulmonary function and/or IPF,” the researchers wrote.