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Painful Bone Metastases: RTOG Trial 9701 Finds Response Rate From 8 Gy
Single Fraction Radiotherapy As Effective As A Longer Course
(July 2005)
“Randomized Trial of Short- Versus Long-Course Radiotherapy
for Palliation of Painful Bone Metastases”, JNCI, June 1,2005, reports the
findings of a collaboration of 11 major institutions as to “whether 8 Gy
delivered in a single treatment fraction provides pain and narcotic relief
that is equivalent to that of the standard 30 Gy delivered in 10 treatment
over 2 weeks.” The study included 898 patients with prostate and breast
cancer. The answer to the study query was affirmative. Measured at 3
months “The overall response was 66%. Complete and partial response rates
were 15% and 50%, respectively in the 8-Gy arm compared with 18% and 48%
in the 30-Gy arm.” The criteria for complete response was perhaps
unrealistically strict - zero pain and zero narcotic use - since pain from
other causes might prompt the need for analgesia. Grade 2-4 toxicity
favored the 8-Gy group, 10% versus 17%. Retreatment was employed in 18% of
the single fraction group compared to 9% in the 30-Gy arm.
The accompanying editorial put the results of the RTOG
study into perspective and asked “How Much More Evidence Is Needed?” There
is no current consensus as to the optimal fractionation schedule. 20 Gy in
five treatments is common in Canada, and single fraction treatment with 8
Gy is most common in European countries. All told there are 40 variations.
The editorial reviews the Dutch Bone Metastases Study (1171
patients)and the Bone Pain Trial Working Group trial (765 patients) both
of which found an equivalent response efficacy for an 8-Gy schedule
compared to a multifraction schema. Overall response in the Dutch study
was 71% with 35% CRs; and for the BPTWG trial overall response was 78% and
CR 57%. The retreatment rate for the single fraction vs multifraction in
the Dutch study was 24% vs 6%, and in the BPTWG, 23% vs. 10%.
Athough the editorial acknowledges that the retreatment
rate “may be of concern to some oncologists”, it points out that in the
RTOG study there was “no statistically significant difference in the
treatment failure rate in the two arms” and speculated that the ease of a
single fraction retreatment may have favored its use. In the Dutch study
“Retreatment for nonresponders was successful in 66% of the
single-fraction group but in only 33% of the multiple-fraction group
(P=.24)”.
Bottom Line:
In three very large randomized trials 8-Gy radiation therapy delivered in
a single fraction “is sufficient to achieve palliation of painful bone
metastases.” [Editorial, above]
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