REPEAT RT FOR BONE METASTASES

NEW YORK (Reuters Health) Jan 07 - Patients with painful bone metastases have a good chance of benefiting from a second round of palliative radiation, regardless of treatment schedule, according to a new randomized controlled trial.

About half of patients treated with either 8 Gy in a single fraction or 20 Gy in multiple fractions had less pain after treatment, Dr. Edward Chow of the Sunnybrook Odette Cancer Centre at the University of Toronto and colleagues found. The benefit was similar whether or not the patients had responded to their first round of radiation.

Although there is evidence that repeat radiation can be an effective palliative treatment in patients with painful bone metastases, Dr. Chow and his team note in Lancet Oncology, to date the optimal dose and fractionation schedules for repeat treatment have not been evaluated.

To investigate, the researchers randomly assigned 850 patients to either 8 Gy or 20 Gy. (The 20 Gy were delivered in five to eight fractions.)

The study's primary endpoint was overall pain response at two months, or the sum of patients who had a complete response and those who had a partial response. A complete response was defined as a Brief Pain Inventory worst-pain score of zero with no increase in daily oral morphine equivalent. Partial responses involved continuing pain with a worst-pain score reduction of at least two points and no increase in morphine consumption; or no increase in pain and a reduction of at least 25% in morphine consumption.

About a third of the patients in each group could not be assessed at two months. Based on a per-protocol analysis, 116 of 258 patients (45%) given 8 Gy had an overall pain response and 134 of 263 patients (51%) in the 20 Gy group had an overall response. Using an intention-to-treat analysis, response rates were 28% and 32%, respectively.

Among the 466 patients for whom data were available on quality-of-life pain scores, 68% showed improvement.

The most common side effects at 14 days were loss of appetite (56% of patients given 8 Gy vs. 66% of patients given 20 Gy; p=0.011) and diarrhea (23% and 31%, respectively; p=0.018). A similar number of patients in both groups sustained pathological fractures, while seven (2%) of the patients in the 8 Gy group and two (<1 20="" cauda="" compressions="" cord="" equina="" group="" gy="" had="" in="" or="" p="0.094).</p" spinal="" the="">

"In patients with painful bone metastases requiring repeat radiation therapy, treatment with 8 Gy in a single fraction seems to be non-inferior and less toxic than 20 Gy in multiple fractions; however, as findings were not robust in a per-protocol analysis, tradeoffs between efficacy and toxicity might exist," Dr. Chow and his team write.

"We've been waiting for a study like this for 20 years, I honestly didn't know it would ever get done," Dr. Stephen Lutz, a radiation oncologist at the Blanchard Valley Regional Cancer Center in Findlay, Ohio, told Reuters Health. "This was a hard study to get together and get finished, and they did a really good job." Dr. Lutz is the primary author of the American Society for Radiation Oncology's guidelines on palliative radiotherapy for bone metastases, and did not take part in Dr. Chow's research.

"External beam radiation is very effective in getting rid of pain from bone metastases," Dr. Lutz added. "For the people that it doesn't work on, there's always been some question over whether it should be tried a second time." And the findings show that a second trial does work for many patients, he said.

"There's all sorts of ways to deal with pain, but something easy and quick is really welcome," he added.

While it is "unfortunate" that so many patients in the study did not complete the two-month assessment, leaving uncertainty about the differences between the two treatments, "that is quite typical for trials of palliative treatment in patients with limited life expectancy," Dr. Carsten Nieder of Nordland Hospital in Bodo, Norway, told Reuters Health. Dr. Nieder wrote an editorial accompanying the study.

Nevertheless, he added, in patients for whom a more complex regimen would clearly be burdensome (for example, those with a limited life expectancy or who live far from a radiation oncology facility), the findings confirm that a single fraction is the appropriate choice.

"Whether baseline factors that were not analysed in the study (eg, small or large volume disease, sclerotic or lytic lesions) can predict who might benefit from multiple fractions needs further clarification, ideally in studies stratified for tumour characteristics," Dr. Nieder writes.

SOURCES: http://bit.ly/K2hQhu and http://bit.ly/K2hQhu

Lancet Oncol 2013.