A central concern.
Top Line: Another brave group, this time from Dublin, has reported its outcomes with ablative radiation for ultra-central lung tumors abutting or involving the trachea or main / lobar bronchi.
The Study: It includes 57 patients with inoperable primary (n=37) or metastatic (n=20) tumors treated with a BED10 ≥72 Gy. Side note: some people may not consider all these fractionation schemes ablative. It’s a little frustrating to again have a mixed bag of prescriptions, but almost all patients (n=50) received 7.5 Gy x 8 = 60 Gy, which yields a BED10 of 105 Gy that squarely falls in the ablative box. What is homogenous among this cohort is fairly homogeneous dose distributions with no max dose exceeding 120%—the hottest 2.0 cc in any patient received a BED10 of 141 Gy. While all patients had a 4D simulation scan, only half required motion management: 14 patients (25%) received treatment with breath hold technique and another 13 patients (23%) received gated treatment. At just over 2 years median follow-up, freedom from local progression at 2 years was 92%. However, five patients died of fatal hemoptysis: two attributed to tumor recurrence, two attributed to radiation, and one unknown. Perhaps the most elucidative finding was learned from dosimetric discrepancies between those who experienced hemoptysis (n=5) and those who didn’t (n=52). While there was no difference in BED3 to the hottest 0.1 cc of central airways (trachea through lobar bronchi), there was a clear distinction in BED3 to the hottest 4.0 cc of central airways: median of 147 Gy with subsequent hemoptysis versus 47 Gy without.
TBL: Albeit effective, ablative radiation to central lung tumors once again results in grade 5 toxicity when hot spots are not vigorously avoided in central airways. | Mihai, Clin Oncol 2021