An advanced type of radiotherapy has shown promise in the treatment of recurrent lung cancer. 

In a study by researchers at the University of Texas MD Anderson Cancer Center, the technique – known as intensity modulated proton therapy (IMPT) – led to a majority of recurrent lung cancer patients being disease-free for at least one year post-treatment, whilst experiencing few severe side effects.

The technique was investigated in 27 patients treated with IMPT between 2011 and 2016 who had already been given radiotherapy and their disease had recurred. After a median follow-up period of 11.2 months, median overall survival was 18 months and one-year overall survival was 54%.

After one year, 61% of patients were recurrence-free whilst 51% remained progression-free.

“Historically, repeat radiation at a higher, curative dose was not possible with older, less precise radiation techniques because the cumulative radiation dose necessary to treat the cancer would cause too much toxicity,” said Jennifer Ho, the study’s lead author. “In lung cancer, tumours are close to the oesophagus, aorta and spinal cord, and all of these critical structures are vital for the body to function.”

Unlike traditional radiotherapy, which affects all tissues in the path of an X-ray beam, IMPT delivers a series of proton beams that reach their highest intensity once they arrive at a tumour, making the technique a potentially less-damaging form of radiotherapy.

The technique is particularly of interest in recurrent lung cancer which, in the majority of cases, cannot be treated with surgery or responds poorly to chemotherapy.

In the past, lung re-irradiation with traditional techniques led to moderate to severe toxicity. In this case, re-irradiation was well tolerated, with few patients experiencing moderate side effects.

“With the advancement of IMPT, we knew that we were able to generate more precise radiation treatment plans that spared normal tissue, but we weren’t sure if this would translate into beneficial clinical outcomes until we analysed this data,” said Joe Chang, professor at Radiation Oncology. “While the findings are early, we’re hopeful that we can offer more positive outcomes and low toxicity with IMPT for recurrent thoracic cancer patients who previously had few treatment options.”

Researchers are now looking to test their findings in a larger population.