PHILADELPHIA (September 22, 2020) – Patients with cancer who have had prior radiation to the pelvic region often have very few treatment options if the cancer comes back or a new cancer is discovered in the same location. Researchers at Fox Chase Cancer Center have now shown that pulsed low-dose rate radiation for pelvic reirradiation was a safe treatment option that resulted in high rates of pain reduction.
Pulsed low-dose rate radiation therapy (PLDR-RT) delivers conventional radiation doses in pulses of small doses with intermittent pauses, said Joshua E. Meyer, MD, associate professor in the Department of Radiation Oncology. Meyer was senior author of the study, which was conducted with a number of colleagues at Fox Chase, and the lead author was Jonathan Paly, DO, senior radiation oncology resident.
“This technique has been around for about 15 years or so, but is not used all that commonly,” Meyer said. “The technique does require a bit of expertise in terms of the way the radiation is planned and delivered, and delivery requires more time. Delivery of PLDR-RT takes about three times as long as standard radiation.”
Experts at Fox Chase have been employing PLDR-RT for more than 10 years in patients requiring reirradiation, but there were not any studies reporting safety and efficacy of PLDR-RT reirradiation to the pelvis.
In the study, Meyer and colleagues looked at outcomes from patients who underwent PLDR-RT for cancers of the prostate, rectum, bladder, gynecologic cancers, or others. Twenty-three patients were treated with a curative intent and 15 were treated palliatively.
At one-year, 59% of patients treated for curative intent had a clinical, biochemical, or radiographic response, and six of the 23 patients had no evidence of disease at their last follow-up. Among the patients treated palliatively, 61% had a clinical or radiographic response.
Of the 50% of patients who reported pain at the local site before treatment, 68% reported an improvement in pain after PLDT-RT.
About 5% of patients experienced grade 1 and 2 acute skin or soft tissue toxicity. The highest rates of toxicity observed were acute grade 2 genitourinary complications, which affected 21% of patients. Less than 8% of patients had a grade 3 toxicity.
“There are more patients who benefit from retreatment now than there used to be, largely due to the fact that systemic therapy has improved in a number of disease sites and patients have a greater need for durable control,” Meyer said. “We always have patients on treatment with this technique in our department and it is reassuring to see that what we have been practicing is benefiting patients.”
The paper, “Pelvic Reirradiation Utilizing Pulsed Low-Dose Rate Radiation Therapy,” was published in the American Journal of Clinical Oncology.