What dose constraints do you use for the pulmonary vein, pulmonary artery, and superior vena cava for thoracic reirradiation after prior conventional fractionation to a central lung tumor?

In my opinion, the best paper to address this is from Stanford University. The authors describe normal tissue toxicity after thoracic reirradiation. Various dose fractionation schedules were used for both the 1st and 2nd courses of radiation, with dose converted to conventional fractionation (2 Gy equivalent; EQD). For each organ at risk (OAR), they plotted histograms with the cumulative dose on the x axis (in EQD) and the number of patients receiving that dose on the y axis, with the number of patients who developed toxicity depicted in color. Relevant to this question – toxicity risks for SVC and aorta were analyzed; the pulmonary vessels were not specifically analyzed. No toxicity was reported, even with some patients having received >75...

After completing an in house prospective trial of SBRT boost (most frequently 650cGyX 3) to the residual primary mass in stage III lung patients who had already received 60Gy standard chemoradiation, we assessed doses received by the pulmonary vasculature in an effort to estimate the tolerated BED. (see Feddock et al., J. Radiosurgery and SBRT 2(3):235-242 2013). The pulmonary vasculature was contoured. Careful analysis of doses based on L-Q modeling to estimate BED (i.e. 60Gy/200cGy/fraction + SBRT 1950cGy @ 650cGy/fraction), we concluded that it was prudent to limit the pulmonary artery to less than 185Gy BED3, and to less than 120Gy for a 5cc volume; the bronchial wall limit to 175Gy BED3. This would then dictate that a safe SBRT dose to...

Re-irradiation of the chest has been specifically studied by MD Anderson in a 2018 PRO journal paper using Intensity Modulated Proton Therapy (IMPT). 81% of patients had centrally located tumors. Based on their results and others, <120 Gy to great vessels appears to be reasonably safe.

They showed that re-treatment with proton doses of 66 Gy or more is feasible and tolerable, without any Grade 4 or 5 toxicity (ie, no major bleeds, only one patient had hemoptysis, grade 2). They also found improved progression free survival when at least 66 Gy was delivered with IMPT: 1-year progression-free survival (76% vs 14%; P = .050). Many of these patients received well over 100 Gy between 2 courses. Similar to Dr. McGarry, they constrained the "major...