Pain Flare Occurs in 4 of 10 Patients After RT for Bone Metastases

Almost 40% of patients undergoing palliative radiotherapy (RT) to treat symptomatic bone metastases experienced pain flare, according to the results of an observational study published in BMC Palliative Care.

Despite this increase in short-term pain flare, researchers led by Alfonso Gomez-Iturriaga, MD, of Hospital Universitario Cruces/Biocruces Health Research Institute in Barakaldo, Spain, concluded that “RT for symptomatic bone metastases is a very effective palliative treatment, in terms of pain control and functional interference.”

The use of palliative RT to treat symptomatic bone pain is well-established, according to the study. However, research has shown that some patients will experience “transitory aggravation of bone pain” after this treatment. In this analysis, Gomez-Iturriaga and colleagues wanted to evaluate the incidence of pain flare among a group of patients undergoing palliative RT and determine if this therapy has an effect on pain control.

The study included 204 patients taken from 10 radiation oncology departments throughout Spain; 135 evaluable patients were included in the published analysis. The primary cancer site varied among the patients; the most common sites were lung (31.1%) and prostate (20%). About one-third of patients received a single fraction of 8 Gy of radiation and about two-thirds received 20 Gy in 5 fractions.

Pain flare was defined as a two-point increase in worst pain score compared with baseline with no decrease in analgesic intake or a 25% increase in analgesic intake compared with baseline with no decrease in worst pain score. The researchers collected pain scores at baseline, daily during the study, and for 10 days after RT.

Overall, 37.7% of patients in the study reported experiencing pain flare.

“Based on our results apparently the advent of the pain flare is more common in the first days after the initiation of RT,” the researchers wrote. About 88% of pain flares occurred on days 1 to 5 after RT. The average duration of patient pain flare was 3 days.

Analyses did not uncover any baseline characteristics that were associated with an increased occurrence of pain flare, including primary cancer site or radiation dose.

The researchers also used the Brief Pain Inventory at baseline and 4 weeks after RT. Results from this survey showed that all items measured at 4 weeks had significant improvement compared with the baseline scores (P < .001).

“Our study demonstrates that pain flare is a common event in patients that receive palliative RT for bone metastases. Despite its frequency, it does not seem to have detrimental effect on the degree of pain control at 4 weeks,” the researchers wrote. “Further studies evaluating whether simple interventions such as prophylactic dexamethasone or short-acting opioids contribute to the prevention or amelioration of the flare phenomenon are warranted.”