Segmental bronchi radiation dose affected the progression of radiation pneumonitis in lung cancer patients.

Objective: To evaluate the association between the segmental bronchi radiation dose and radiation pneumonitis (RP) in patients with lung cancer who underwent radiotherapy.

Methods: A total of 135 patients with lung cancer who were treated with radiation therapy between December 2014 and December 2015 were enrolled in the study. RP was defined and graded according to the criteria of the Radiation Therapy Oncology Group. The radiation dose to the segmental bronchi, along with clinical, and other dosimetric factors were recorded. Logistic regression analysis was used to evaluate the association between the related factors and RP.

Results: Among the 135 enrolled patients, 24 (17.8%) developed grade 3 radiation pneumonitis or higher. Study found that RP was associated with the following factors: patient age, complications with chronic obstructive pulmonary disease, concurrent chemotherapy, percentage of lung volume receiving more than 30 Gy (V30), whole lung volume, and the segmental bronchi maximum and mean dose. Logistic regression analysis showed that the maximum dose of the segmental bronchi, whole lung volume, and V30 were independent risk factors for RP. According to the receiver operating characteristic curve, the maximum dose constraint of the segmental bronchi during radiotherapy is estimated at 23.85 Gy.

Conclusion: The segmental bronchi radiation dose should be considered as a normal tissue constraint, in addition to whole lung volume and V30 in radiotherapy for patients with lung cancer to decrease the incidence of RP.