Association of Computed Tomography-detected Pulmonary Interstitial Changes with Severe Radiation Pneumonitis for Patients Treated with Thoracic Radiotherapy

Abstract

We evaluated associations of interstitial changes with radiation pneumonitis (RP) for patients treated with thoracic radiotherapy. Between 2005 and 2009, patients who received thoracic radiotherapy of 40 Gy or more for lung cancer or thymic tumors and were followed-up for more than 6 months were eligible for this study. Possible risk factors for RP included the presence of interstitial changes on computed tomography before radiotherapy, and elevated C-reactive protein (CRP) and lactate dehydrogenase (LDH) levels; these were compared with the incidences of severe RP. A total of 106 patients were included. The incidences of RP were 4 (4%), 0 (0%), and 5 (5%) for grades 3, 4, and 5, respectively. For those with interstitial changes, the incidence of RP ≥ grade 3 was significantly increased from 3% (2/79) to 26% (7/27) (p < 0.001). CRP and LDH levels were also associated with increased RP, as were pulmonary emphysema and performance status ≥ 2. Among 91 patients with RP ≥ grade 1, RP grade ≥ 3 occurred significantly earlier than grades 1 and 2. In conclusion, pulmonary interstitial changes, LDH and CRP levels, pulmonary emphysema, and performance status ≥ 2 were significantly associated with RP ≥ grade 3. RP grade ≥ 3 occurred significantly earlier than grades 1 and 2. The early appearance of interstitial changes requires careful management due to the possibility of severe RP.

Impact of Pretreatment Interstitial Lung Disease on Radiation Pneumonitis and Survival after Stereotactic Body Radiation Therapy for Lung Cancer

“…[7][8][9][10]12,33 In addition, pre-existing interstitial pneumonia is thought to be a risk factor for fatal RP after SBRT, 12,13 and has been reported in conventional radiotherapy. 34,35 Our results showed that the presence of ILD was a significant risk factor for both ≥ Gr2 RP and ≥ Gr3 RP; the incidences of ≥ Gr2 RP and ≥ Gr3 RP for those with ILD were 55.0% and 10.0%, respectively. Even minimal ILD change was a significant risk factor for ≥ Gr2 RP-the incidence was 50.0%-but not for ≥ Gr3 RP.…”

Pre–Radiation Therapy Fluorine 18 Fluorodeoxyglucose PET Helps Identify Patients with Esophageal Cancer at High Risk for Radiation Pneumonitis

“…Other image parameters were previously found to be predictors of RP, such as RT dosimetric parameters mean lung dose, V5, V20, et cetera (2–5) and pre-RT CT interstitial findings (17,18). In this study, those dosimetric parameters did not reach statistical significance.…”

“…Makimoto et al (17) found that pretreatment radiographic findings of underlying lung disease were associated with a higher incidence of RP (47.1% vs 5.3%, P < .001). Sanuki et al (18) found interstitial findings at CT were associated with grade 3 or higher RP (26% vs 3%, P < .001). Finding these subtle CT features requires an experienced chest radiologist.…”

Nondosimetric Risk Factors for Radiation-Induced Lung Toxicity

“…Patients with pre-existing ILD appear to be more susceptible to acute lung injury after RT, resulting in acute ILD exacerbation. It has been reported that for patients with pre-existing interstitial changes on computed tomography (CT), the incidence of RP ≥ grade 3 was significantly increased to 26% as compared to 3% for those with normal lung [26]. In another study, grade 4–5 RP occurred in 57% of patients with interstitial pneumonitis (IP) as compared to 2% of those without [27].…”