Purpose: To investigate the correlation among DVH (lung dose-volume histogram) parameters, clinical factors, and grade > or = 2 radiation pneumonitis (RP) in patients with locally advanced non-small-cell lung cancer (NSCLC) treated with three-dimensional conformal radiotherapy (3D-CRT), and the differences between patients treated with 3D-CRT alone or that combined with chemotherapy on RP.
Patients and methods: As much as 93 patients of stage III NSCLC were treated with 3D-CRT, among which 36 were treated with chemotherapy after 3D-CRT, 57 received 3D-CRT treatment alone. The radiation dose was 62.5-65 Gy (BED = 68-72.7 Gy).
Results: The morbidity of grade > or = 2 RP was 49.5%, of which grade 2 and grade 3 were 33.3 and 16.1%, respectively. The morbidity of RP in those patients treated with chemotherapy after radiotherapy was evidently higher than that of patients treated with radiotherapy alone (61.1 vs. 42.1%). According to the single factor analysis, V5-V50 and MLD of both the ipsilateral and the whole lung were all related to the occurrence of RP; comparing grade 3 with grade 2 within the same group, except V45, V50, TV20, TV30, and TMLD, other parameters also had their statistical significance (P < 0.01); comparing the non-chemotherapy-treated group with the chemotherapy-treated group, TV30 and TV35 had their statistical significance. According to logistic regression analysis; the occurrence of RP was evidently associated with the comprehensive value of DVH parameters, chemotherapy, and gender. Chemotherapy has increased the risk of RP 7.6 times. The increase of each score in the comprehensive value of DVH parameters would increase the risk of RP 22.7 times.
Conclusion: The comprehensive values of DVH parameters, chemotherapy, and gender have independent effects on the occurrence of RP. Most of DVH parameters were associated with the occurrence of RP. The curve shape composed of multiple points in DVH parameters was more important than any single DVH parameter.