Analysis On Risk Factors Of Radiation Pneumonitis After Three-dimensional Conformal Radiotherapy In Non-small Cell Lung Cancer

Objective: To explore a relationship of incidence in radiation pneu- monitis with its relevant parameters after non-small cell lung cancer (NSCLC) treated with three-dimensional (3D) radiationtherapy was analyzed with dose-volume histogram (DVH).Methods: During September, 2005 and March, 2007, 63 patients withNSCLC were treated with 3D radiation therapy. Forty-two patients weretreated with sequential chemotherapy. All patients had full 3D treatment planning (including total lung dose-volume histograms) prior to treatment delivery. Radiotherapy was delivered to a total dose of 48– 66 Gy at 1.8–2.0 Gy per fraction with a three-dimensional conformal technique. The following dosimetric parameters were generated from the dose-volumehistogram (DVH) for total lung, lung volume, mean dose to lung, and relative volumes of lung receiving more than a threshold dose. Radiation pneumonitis was graded according to RTOG.The relationship of the DVH and clinical relevantparameters with the incidence of radiation pneumonitisafter radiation therapy was analyzed by Univariate analyses. By binary Logistic analyses were performed to assess those factors having univariate significance (P < 0.05) to select the most significant factor associated with radiation pneumonitis.Results: The median follow-up period was 11.5 months (range 10– 12 months). Thirteen of the 63 patients develeped radiation pneumonitis. On univariate analysis, higher relative volume of lung receiving≥7 Gy (V7) (P = 0.036), V10 (P = 0.015),GTV (P = 0.047) and chronic obstructive pulmonary disease (COPD) were all associated significantly with anincreased incidence of radiation pneumonitis complicated by radiation therapy. By multivariate analysis, V07 and V10 ware the most significant factors associated with the incidence of grade 2 or higher radiation pneumonitis.Conclusions: In this study, low dose radiation distributed around target area, and surrounded the greater part of normal lung tissue. The lung volume with the doses of 7 to 10Gy should be attended when usingintrathoracic radiotherapy techniques, which is associated significantly withthe incidence of radiation pneumonitis.