Background
Palliative antalgic treatments represent an issue for clinical management and a challenge for scientific research. Radiotherapy (RT) plays a central role. Techniques such as stereotactic body radiotherapy (SBRT) were largely investigated in several phase 2 studies with good symptom response, becoming widely adopted. Still is lacking evidence from randomized, direct comparison of RT and SBRT.
Methods/Design
The PREST trial was designed as an interventional study without medicinal, randomized 1:1, open-label, multicentric, phase 3. Inclusion criteria: painful spinal bone metastases presenting pain level >4 (or >1 if assuming analgesic) at numeric rating scale (NRS); expected intermediate/high prognosis (superior to 6 months) according to the Mizumoto prognostic score; low spine instability neoplastic score (SINS) sores (<7); magnetic resonance imaging (MRI) assessment of the bulky lesion. Patients will be assigned to either standard conventional radiotherapy administering 4 Gy x5 fractions (fx) to whole involved vertebra or SBRT by intensity modulated radiotherapy with simultaneous integrated boost (IMRT-SIB) administering 7 Gy x3 fx (to the whole involved vertebra) + 10 Gy x3 fx on the macroscopic disease (Gross Tumor Volume -GTV). In the experimental arm, the GTV will be contoured by registration with baseline MRI.
Discussion
Primary endpoint is overall pain reduction, defined in term of variation between baseline and 1-month evaluation; pain will be measured by Numeric Rating Scale (NRS) score. Secondary endpoints include: pain control duration; retreatment rates (after a minimum interval of 1 month); local control assessed with RECIST Criteria; symptom progression free survival; progression free survival; overall survival and quality of life (at 0, 30 and 90 days). Accrual of 330 lesions is planned. Experimental arm is expected to improve overall pain response rates of 15% respect to standard arm (60% according to Chow et al 2012).
The clinical benefits of radiotherapy in pancreatic tumors should not be withheld from patients treated in centers only with two-dimensional technology. Prospective trials, particularly in developing countries, would be useful to evaluate the efficacy in this setting of involved-field two-dimensional treatments using the dose and fractionation defined in this analysis.
Previous trials showed the tolerability and efficacy of a palliative radiotherapy (RT) regimen (SHARON) based on the 4 fractions delivered in 2 days in different oncological settings. In order to identify possible predictors of symptomatic response, the purpose of this study is to perform a pooled analysis of previous trials. We analyzed the impact on symptomatic response of the following parameters: tumor site, histological type, performance status (ECOG), dominant symptom, and RT dose using the Chi-square test and Fisher’s exact test. One-hundred-eighty patients were analyzed. Median RT dose was 20 Gy (range: 14–20 Gy). The overall response rate was 88.8% (95% CI 83.3–92.7%) while pre- and post-treatment mean VAS was 5.3 (± 7.7) and 2.2 (± 2.2), respectively (p < 0.001). The overall response rate of pain, dyspnea, bleeding, dysphagia, and other symptoms was 86.2%, 90.9%, 100%, 87.5%, and 100%, respectively. Comparing the symptomatic effect based on the analyzed parameters no significant differences were recorded. However, patients with locally advanced disease showed a higher rate of symptomatic responses than metastatic ones (97.3% vs 83.0%; p = 0.021). Finally, the complete pain response rate was more than double in patients with mild to moderate (VAS: 4–7) compared to those with severe (VAS > 7) pain (36.0% vs 14.3%; p = 0.028). This pooled analysis showed high efficacy of the SHARON regimen in the relief of several cancer-related symptoms. The markedly and significantly higher complete pain response rate, in patients with mild-moderate pain, suggests early referral to palliative RT for patients with cancer-related pain.
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