The impact of adjuvant radiotherapy (ART) on cancer-specific mortality (CSM) and overall mortality rates in patients who have undergone radical prostatectomy (RP) depends on the cumulative number of certain pathologic features found during surgery, report researchers.
Only patients with at least two of the features are at a significantly higher risk for CSM and are likely to benefit from ART, say Firas Abdollah (Vita-Salute University, Milan, Italy) and colleagues. "Conversely, patients with fewer than two of the risk factors would hardly benefit from ART and may only suffer from its potential adverse effects."
The team evaluated 1049 patients who were treated with RP and extended lymph node dissection alone, or in combination with ART, and who had at least one of the following pathologic findings: positive surgical margins (PSMs), extracapsular extension (ECE), seminal vesicle invasion (SVI), pathologic tumor (pT) stage 4, and/or lymph node invasion (LNI).
Cox regression analysis revealed that only three adverse pathologic features observed during surgery were significantly associated with higher CSM rates. Namely, a Gleason score of at least 8, a pT stage 3 or 4 (categorized by TNM [tumor, nodes, metastasis] classification), and a positive lymph node count of 1 or more significantly increased the risk for CSM, at hazard ratios 5.4, 2.2, and 2.6, respectively.
The total number of these factors shared by each patient was used to construct a novel risk score and CSM-free survival curves were then analyzed after stratification according to the score.
Patients who were treated with versus without ART had 10-year CSM-free rates of 79.9% versus 69.6% when they had a risk score of 2 or more (more than two of the predictors) while the corresponding rates were 97.6% versus 96.6% in patients with a risk score of less than 2.
Similarly, the 10-year overall mortality-free rate in men treated with versus without ART was 75.6% versus 62.7% for patients with a risk score of at least 2, while it was 95% versus 88.5% for patients with a risk score of less than 2.
"From a clinical perspective, the classification of patients according to our novel risk score might be considered easier and more practical, especially when a physician has to decide on the need of ART after RP," suggests the team.
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