Top Line: Could moderate hypofractionation be an alternative to twice daily radiation when treating LS-SCLC?
The Study: 45 Gy in 30 BID fractions is considered the standard radiation regimen for LS-SCLC. In the CONVERT trial, 66 Gy in 33 daily fractions was not superior to 45 Gy in 30 BID. A recent phase 2 trial found that there may be room for improvement, though, with improved outcomes for 60 Gy in 40 BID fractions. On the other hand, for many patients and centers, a single daily fraction is the most practical approach to delivering radiation. Could hypofractionated daily treatment shorten the overall treatment time and improve outcomes compared to BID treatment? This randomized phase 2 study compared progression free survival (PFS) outcomes for 45 Gy in 30 BID fractions and 65 Gy in 26 daily fractions in nearly 200 patients with LS-SCLC. The PTV was a 5 mm expansion from GTV accounting for respiratory motion. OAR constraints were prioritized over target coverage, but those constraints were fairly standard. Everyone received 4-6 cycles of cis/etoposide, and those with good response then received PCI (25 Gy in 10 fractions). Median PFS was significantly longer in the hypofractionated arm (13 → 17 months), and the 2-year PFS rate went from 28 → 42%. There were no differences in toxicity between groups with 15-17% having grade 3+ esophagitis and 2-3% having grade 3+ pneumonitis.
TBL: In this randomized phase 2 trial, moderately hypofractionated daily radiation improved PFS over standard twice daily radiation for patients with LS-SCLC. | Qiu, Int J Radiat Oncol Biol Phys 2021