Risk‐adapted stereotactic body radiation therapy for central and ultra‐central early‐stage inoperable non‐small cell lung cancer

Abstract

To determine the therapeutic efficacy and safety of risk‐adapted stereotactic body radiation therapy (SBRT) schedules for patients with early‐stage central and ultra‐central inoperable non‐small cell lung cancer. From 2006 to 2015, 80 inoperable T1‐2N0M0 NSCLC patients were treated with two median dose levels: 60 Gy in six fractions (range, 48‐60 Gy in 4‐8 fractions) prescribed to the 74% isodose line (range, 58%‐79%) for central lesions (ie within 2 cm of, but not abutting, the proximal bronchial tree; n = 43), and 56 Gy in seven fractions (range, 48‐60 Gy in 5‐10 fractions) prescribed to the 74% isodose line (range, 60%‐80%) for ultra‐central lesions (ie abutting the proximal bronchial tree; n = 37) on consecutive days. Primary endpoint was overall survival (OS); secondary endpoints included progression‐free survival (PFS), tumor local control rate (LC), and toxicity. Median OS and PFS were 64.47 and 32.10 months (respectively) for ultra‐central patients, and not reached for central patients. Median time to local failure, regional failure, and any distant failures for central versus ultra‐central lesions were: 27.37 versus 26.07 months, 20.90 versus 12.53 months, and 20.85 versus 15.53 months, respectively, all P < .05. Multivariate analyses showed that tumor categorization (ultra‐central) and planning target volume ≥52.76 mL were poor prognostic factors of OS, PFS, and LC, respectively (all P < .05). There was one grade 5 toxicity; all other toxicities were grade 1‐2. Our results showed that ultra‐central tumors have a poor OS, PFS, and LC compared with central patients because of the use of risk‐adapted SBRT schedules that allow for equal and favorable toxicity profiles.

The HILUS-Trial—a Prospective Nordic Multicenter Phase 2 Study of Ultracentral Lung Tumors Treated With Stereotactic Body Radiotherapy

“…No consensus exists on the definition of the ultracentral location, and dependent on the used definition, both the PBT, 10,[13][14][15][16][19][20][21][22][23][24] or the main bronchi specifically, 8,9,17 and other central thoracic structures 12,13,15,16,19,20,24 may be the OAR of primary concern at treatment. Results from the current study, in which the main risk organ was the PBT, indicate that injury to the main bronchi or trachea results in increased risk for high-grade toxic effects.…”

Salvage stereotactic body radiotherapy for post‑operative oligo‑recurrence of non‑small cell lung cancer: A single‑institution analysis of 59�patients

“…The central lesion was defined as a tumor <2 cm from the proximal bronchial tree, according to the RTOG 0236 guidelines, or <2 cm in any direction from a critical mediastinal structure, including the bronchial tree, esophagus, heart, brachial plexus, major vessels, spinal cord, phrenic nerve and recurrent laryngeal nerve, as in most recent studies (44,45). For certain hilar or mediastinal tumors, or tumors invading the trachea or bronchi, a regimen with increased number of fractions (such as 50 Gy in 10 fractions) was used (46,47).…”

Revisiting the formalism of equivalent uniform dose based on the linear-quadratic and universal survival curve models in high-dose stereotactic body radiotherapy

“…In this study, the calculated values for the LQ-EUDCFRT predict a 3-year local progression-free survival (LPFS) rate of almost 100.0%. In contrast, using the USC-EUDCFRT values would yield a more reasonable LPFS estimation (median 93.8%) but still higher than the median of 56.5% (range 95.9-46.0%) reported in the literature [32][33][34][35][36][37][38]. Such deviation of predicted outcome from actual clinical data is likely due to the model parameters used to estimate the LPFS and the slightly more potent dose regime (20 Gy for three fractions) used in this study.…”