IMRT improved high risk prostate cancer outcomes

Intensity-modulated radiation therapy reduced cancer-specific mortality among patients with high-risk prostate cancer but not those with low- or intermediate-risk disease, according to results of a population-based study.

“There has been a rapid adoption of IMRT in patients with prostate cancer, despite the lack of randomized trials evaluating its effectiveness,” the researchers wrote. “The aim of our study was to evaluate the survival benefit associated with IMRT in patients with prostate cancer.”

Researchers used the SEER-Medicare database to identify 42,483 patients with prostate cancer who underwent IMRT or observation between 2001 and 2007.

The analysis included 19,064 patients who were matched in both treatment arms using propensity-score methodology.

Among all patients, 8-year cancer-specific mortality was 3.4% in the IMRT arm vs. 4.1% in the observation arm (number needed to treat [NNT], 142; P˂.001).

Researchers then stratified results based on risk category.

Among patients with low- or intermediate-risk disease, 8-year cancer-specific mortality did not significantly differ between those who underwent IMRT and those who underwent observation (P=.7).

However, IMRT significantly reduced 8-year cancer-specific mortality among high-risk patients (5.8% vs. 10.5%; NNT, 21; P˂.001).

Researchers observed a cancer-specific mortality benefit with IMRT vs. observation among high-risk patients younger than 73 years (4.3% vs. 9.4%; NNT, 19) and those aged at least 73 years (6.9% vs. 11.9%; NNT, 21; P˂.001 for both).

IMRT also was associated with improved cancer-specific mortality among high-risk patients with a Charlson comorbidity index score ≤1 (5.3% vs. 11.4%; NNT, 16) and ˃1 (6.1% vs. 10.1%; NNT, 25; P˂.001 for both) compared with observation.

However, multivariate analyses indicated IMRT benefit was more significant among high-risk patients who were younger and had lower comorbidities.

Disclosure: See the study for a full list of the researchers’ relevant financial disclosures.