Navigating the highlights of phase III trials: a watchful eye on evidence-based radiotherapy

Phase III randomized controlled trials (RCTs) are the cornerstone of evidence-based oncology. However, there is no exhaustive review describing the radiotherapy RTCs characteristics. The objective of the present study was to describe features of all phase III RCTs including at least a radiation therapy.

Requests were performed in the Medline database (via PubMed). The latest update was performed in April 2016, using the following MESH terms: 'clinical trials: phase III as topic', 'radiotherapy', 'brachytherapy', as keywords.

A total of 454 phase III RCTs were identified. Studies were mainly based on open (92.1%) multicenter (77.5%) designs, analyzed in intend to treat (67.6%), aiming at proving superiority (91.6%) through overall survival assessment (46.5%). Most frequently studied malignancies were head and neck (21.8%), lung (14.3%) and prostate cancers (9.9%). Patients were mainly recruited with a locally advanced disease (73.7%). Median age was 59 years old. Out of 977 treatment arms, 889 arms experienced radiotherapy, mainly using 3D-conformal radiotherapy (288 arms, 32.4%). Intensity-modulated techniques were tested in 12 arms (1.3%). The intervention was a non-cytotoxic agent addition in 89 studies (19.6%), a radiation dose/fractionation modification in 74 studies (16.3%), a modification of chemotherapy regimen in 63 studies (13.9%), a chemotherapy addition in 63 studies (13.9%) and a radiotherapy addition in 53 trials (11.7%). With a median follow-up of 50 months, acute all-grade and grade 3-5 toxicities were reported in 49.6% and 69.4% of studies, respectively. Radiotherapy technique, follow-up and late toxicities were reported in 60.1%, 74%, and 31.1% of studies, respectively.

Phase III randomized controlled trials featured severe limitations, since a third did not report radiotherapy technique, follow-up or late toxicities. The fast-paced technological evolution creates a discrepancy between literature and radiotherapy techniques performed in daily-routine, suggesting that phase III methodology needs to be reinvented.