A large Taiwanese retrospective look at outcomes following definitive proton (n=105) or photon (n=54) radiation for localized HCC >5 cm reveals a significant advantage with biologically effective doses ≥ 75 Gy (n=119) in terms of 2-year local control (86% vs. 21%) and median progression-free (7.4 vs. 3.2 months) and overall (18.1 vs. 7.3 months) survival. This was achieved with 72.6 Gy in 22 fractions when within 1 cm of GI tract or porta hepatis and 66 Gy in 10 fractions otherwise. Of note, prescription above this threshold was heavily skewed towards proton (96%) versus photon (33%) treatment. Why? Dosimetric investigations with post-hoc photon comparison plans “indicated that the favorable dosimetric characteristics of protons allowed ablative doses…while leaving a large proportion of surrounding normal organs untouched by radiation.” | Hsieh, Int J Radiat Oncol Biol Phys 2023
