Prediction of GTV/LV for radiation pneumonitis in patients with stage Ⅲ non-small cell lung cancer after radical radiotherapy

Objective: To analyze relevant clinical and dosimetric factors associated with radiation pneumonitis in patients with stage Ⅲ non-small cell lung cancer after they received radical radiotherapy. Methods: A total of 126 patients with stage Ⅲ non-small cell lung cancer who received precision radiotherapy in Peking University Cancer Hospital were analyzed from January 2013 to December 2014. Data were collected including various clinical factors (including sex, age, histological type, tumor location, history of diabetes, history of hypertension, history of smoking, the season patients received treatment, ECOG performance status before treatment, chemotherapy before radiotherapy, concurrent chemotherapy and the classification of radiation pneumonitis), as well as related dosimetric parameters [including GTV, lung volume (LV), bilateral V₅, V₁₀, V₂₀, V₃₀ and MLD]. SPSS 19.0 software was used to analyze the relation between correlation factors and radiation pneumonitis (RP ≥ 2). Results: Among the patients, 31 cases (24.6%) had occurrance of radiation pneumonitis ≥ 2. Univariate analysis showed that age, ECOG performance status before treatment, concurrent chemotherapy and GTV/LV ratio were significantly correlated with RP ≥ 2 (R = 0.157-0.222, P < 0.05). Further multivariate Logistic regression showed that age, concurrent chemotherapy and GTV/LV ratio were significantly correlated(Wald = 4.754, 6.422, 14.79, P < 0.05). Conclusions: In patients with stage Ⅲ non-small cell lung cancer after receiving thoracic radical radiotherapy, increasing age and GTV/LV ratio ≥ 3.2% are risk factors of RP ≥ 2. The concurrent chemotherapy with low-dose paclitaxel might also increase the risk of RP ≥ 2. (authors)