Radiation Dose to the Thoracic Vertebral Bodies is Associated with Acute Hematologic toxicities in Patients Receiving Concurrent Chemoradiation for Lung Cancer : Results of a Single Center Retrospective Analysis
Menée à partir de données portant sur 201 patients atteints d'un cancer du poumon traité entre 2007 et 2016 par chimioradiothérapie concomitante, cette étude met en évidence une association entre la dose de rayonnements reçue par les vertèbres thoraciques et la survenue de complications hématologiques sévères
Introduction : Chemoradiation (CRT) for the treatment of lung cancers is often associated with severe acute hematologic toxicities (HT). We hypothesized that increasing radiation (RT) dose to the thoracic vertebral bodies (TVB) contributes to the development of HT in this population.
Methods : Cases of non-small cell (NSCLC) and small cell (SCLC) lung cancer treated with definitive CRT with concurrent platinum-based doublet chemotherapy at our institution from 2007 to 2016 were identified. Mean TVB dose and the volume of TVB receiving at least 5-60 Gy (V5-V60) were retrospectively recorded. Logistic regression was used to test associations between grade≥3 HT (HT3+) and dosimetric/clinical parameters. Normal tissue complication probability was evaluated using the Lyman-Kutcher-Burman (LKB) model for HT3+ and receiver operating characteristics (ROC) analysis was used to determine dosimetric cutpoints.
Results : We identified 201 patients, the majority having NSCLC (N=162, 81%) and stage III-IV disease (N=179, 89%). All patients received either cisplatin/etoposide (N=107, 53%) or carboplatin/paclitaxel (N=94, 47%). Median RT dose was 60 Gy (range, 60-70 Gy). The rate of HT3+ was 49% (N=99). Increasing mean TVB dose (per Gy) was associated with higher odds of developing HT3+ (OR=1.041, 95% CI 1.004-1.080, p=.032) as were increasing TVB V5-V20. These dosimetric correlates to HT3+ persisted on multivariate analysis. Constrained optimization of the LKB model for HT3+ yielded the parameters: n=1, m=1.79, and TD50=21.4 Gy. Optimal cutpoints identified were V5=65%, V10=60%, V20=50%, and mean dose=23.5 Gy. Patients with values above these cutpoints had a 2-fold increased risk of HT3+.
Conclusions : We found that mean TVB dose and low-dose parameters (V5-V20) were associated with HT3+ in CRT for lung cancer. Per the LKB model, bone marrow behaves like a parallel organ (n=1), implying that mean TVB dose is a useful predictor for toxicity. These data suggest that efforts to spare dose to the TVB may reduce rates of severe HT.
International Journal of Radiation Oncology • Biology • Physics , résumé, 2016