Acute radiation pneumonitis after conformational radiotherapy for nonsmall cell lung cancer: Clinical, dosimetric, and associated-treatment risk factors

Abstract

Conformational thoracic radiotherapy (CTR) is a key-treatment in locally advanced nonsmall cell lung cancer (LA-NSCLC). Acute radiation pneumonitis (ARP) is one of the major complications. To evaluate the predictors of ARP after CTR in the treatment of LA-NSCLC. A total of 47 consecutive patients (pts) were treated with CTR for LA-NSCLC and retrospectively analyzed. The mean total dose of radiation therapy (RT) was 65 Gy, with respiratory gating (RG) in 19 cases. Induction and concomitant chemotherapy was performed in 33 pts (70%) and 41 pts (87%), respectively. Eleven pts (23%) had an ARP resulting in death for one pt. In univariate analysis, age, sex, pretherapeutic value of forced expiratory volume (FEV), not-gated radiotherapy and type of concomitant chemotherapy did not appear as contributing factors in contrast to the administration of induction gemcitabine ( p = 0.03). The occurrence of ARP was significantly associated with nontumor lung volumes irradiated to 13 Gy (V13, p = 0.04), 20 Gy (V20, p = 0.02), and 25 Gy (V25, p = 0.006), the mean lung dose ( p = 0.008) and lung normal tissue complication probability (NTCP) ( p = 0.004). In multivariate logistic regression analysis, the occurrence of ARP was significantly associated with age >75 years (odds ratio (OR) = 16.72, confidence interval (CI) 95% 1.77-157.87) and administration of induction gemcitabine (OR = 18.08, CI 95% 1.09-300.08). ARP is a common acute complication, requiring close posttreatment follow-up, particularly for elderly patients. The use of gemcitabine before radiation should be avoided. The benefits and risks of CTR must be carefully analyzed, according to the dosimetric parameters.