Ultra-central lung tumors: safety and efficacy of protracted stereotactic body radiotherapy

Abstract

Background: For patients with early stage or medically inoperable lung cancer, stereotactic body radiotherapy (SBRT) is a general accepted and effective treatment option. The role of SBRT in ultracentral tumors remains controversial. The aim of this single-center retrospective analysis was to evaluate the safety and efficacy of protracted SBRT with 60 Gy in 12 fractions (with a biological effective dose (BED 10 ) of 90-150 Gy) for patients with ultra-central lung tumors. Materials and methods: Patients with ultra-central lung tumors treated in our institution with 60 Gy in 12 fractions from January 2012 until April 2020 were included. Ultra-central tumors were defined as planning target volume (PTV) abutting or overlapping the main bronchi and/or trachea and/or esophagus. Data regarding patient-, tumor-, and treatment-related characteristics were evaluated. Results: A total of 72 patients met the criteria for ultra-central tumor location. The PTV abutted the main bronchus, trachea or esophagus in 79%, 22% and 28% of cases, respectively. At a median followup of 19 months, 1-and 2-year local control rates were 98% and 85%, respectively. Overall survival rates at 1 and 2 years were 77% and 52%, respectively. Grade 3 or higher toxicity was observed in 21%, of which 10 patients (14% of total) died of bronchopulmonary hemorrhage. A significant difference between patients with or without grade !3 toxicity was found for the mean dose (D mean ) to the main bronchus (p ¼ 0.003), where a D mean BED 3 of !91 Gy increased the risk of grade !3 toxicity significantly. Discussion: A protracted SBRT regimen of 60 Gy in 12 fractions for ultra-central lung tumors leads to high local control rates with toxicity rates similar to previous series, but with substantial risk of fatal bronchopulmonary hemorrhage. Therefore, possible risk factors of bronchopulmonary hemorrhage such as dose to the main bronchus should be taken into account.

Survival and Prognostic Factors of Ultra-Central Tumors Treated with Stereotactic Body Radiotherapy

“…Median OS was 29 months and 1-year, and 2-year OS rates were 75% and 58%, respectively. Similar results were reported by Breen et al [ 21 ] and Lodeweges et al [ 19 ], with 1-year and 2-year OS rates of 78% and 57%, and 77% and 52%, respectively. One-year LC was 97% in the study reported by Guillaume et al [ 17 ], and 98% in the work by Lodeweges et al [ 19 ], slightly higher than our findings.…”

“…Similar results were reported by Breen et al [ 21 ] and Lodeweges et al [ 19 ], with 1-year and 2-year OS rates of 78% and 57%, and 77% and 52%, respectively. One-year LC was 97% in the study reported by Guillaume et al [ 17 ], and 98% in the work by Lodeweges et al [ 19 ], slightly higher than our findings. Across the studies investigating SBRT for ultra-central tumors, there was a significant heterogeneity in terms of fractionation schedules.…”

First experimental demonstration of VMAT combined with MLC tracking for single and multi fraction lung SBRT on an MR-linac

“…These undesired high dose areas could damage surrounding tissue [2,12]. This is also important for central tumours, for which intensified hypofractionation is currently often not recommended because of toxicity risks [33]. The high precision of VMAT + MLC tracking could increase the feasibility of single fraction deliveries for more patients, while also increasing patient comfort with the possibility of free-breathing during treatment and no extended beam-on times (100% duty cycle).…”

Safety and Efficacy of Stereotactic Ablative Radiotherapy for Ultra-Central Lung Cancer

“…For fatal hemoptysis, central tumor location is a critical factor. Another research concluded that a mean dosage to the major bronchus of 91 Gy significantly increased the probability of grade ≥3 toxicity ( 24 ). Recently, the HILUS-Trial suggested that the dose to the combined structure’s main bronchi and trachea, as well as the distance of the tumor from the main bronchi, were significant risk factors.…”