A hot mess.
A hotly debated topic in thoracic radiation oncology is the best balance of tumor control and treatment toxicity when treating inoperable ultra-central lung tumors. A recent review landed on 7.5 Gy x 8 as a good option, recognizing a single prescription can result in vastly different plans depending on the allowable hot spot. This week the phase 2 HILUS trial reported on outcomes among 65 patients receiving 7 Gy x 8 to tumors within 1 cm of the proximal bronchial tree (i.e. the highest of high-risk ultracentral tumors). In fact, the median distance was actually touching the proximal bronchial tree. Unfortunately, grade 3+ toxicities occurred in over one-third of patients (n=22) including 10(!) grade 5 toxicities due to bronchopulmonary hemorrhage (n=8), pneumonitis (n=1), and fistula (n=1). Critics would argue it was the allowed hot spot (150%), not the prescription, that was to blame. And, indeed, dosimetric modeling revealed max dose to 0.2cc of the main bronchi/trachea was a primary predictor of lethal bronchopulmonary hemorrhage. | Lindberg, J Thorac Oncol 2021