Stereotactic body radiotherapy for lung tumors in patients with subclinical interstitial lung disease: The potential risk of extensive radiation pneumonitis
Introduction
Stereotactic body radiotherapy (SBRT) has become widespread as a new treatment modality for pulmonary lesions in recent years due to its high local control rate and completely painless and ambulatory treatment. Although adverse reactions are not recognized in most patients treated with SBRT, radiation pneumonitis (RP) is an occasional complication of SBRT. Previous reports have shown a correlation between severe RP and dose–volume parameters, such as the mean lung dose (MLD), V20 (percentage of the lung volume receiving > 20 Gy) and V5 [1], [2].
A group of noninfectious, acute and chronic diffuse parenchymal lung disorders are classified as interstitial lung disease (ILD). More than 150 clinical conditions and/or causes are associated with ILD [3]. The COPD Gene Study group previously demonstrated both chest computed tomographic (CT) and pathologic evidence of subclinical ILD in asymptomatic members; 194 (8%) of 2416 screening HRCT scans in a cohort of smokers showed interstitial lung abnormalities [4]. The frequency of acute exacerbation following conventional radiotherapy in patients with ILD has been reported to be around 25% [5], [6]. The eligibility criteria for patients in a phase I/II study of SBRT to treat primary lung cancer showed that active ILD is a factor for patient exclusion [7]. The clinical guidelines for SBRT published by the Japanese Society for Therapeutic Radiology and Oncology also recommend that SBRT should be relatively contraindicated in patients with severe ILD.
Beginning in August 2005, at our institution, the use of SBRT to treat patients with stage I non-small cell lung cancer (NSCLC) or metastatic lung tumors was initiated according to our own protocols. Patients with subclinical (untreated and oxygen-free) ILD were treated with SBRT, while those with clinical ILD were not. To our knowledge, there are only a few case series evaluating SBRT in patients with subclinical ILD [8], [9], [10]. The purpose of our study was to evaluate the toxicity and efficacy of thoracic SBRT in patients with subclinical ILD and to investigate whether subclinical ILD is a predictor of RP.
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Patients
Between August 2005 and February 2011, SBRT was performed to treat lung tumors at our institution in 109 consecutive patients with 138 lung tumors. For this study, we retrospectively collected data for patients who received follow-up for a minimum of six months. Nine patients who were followed up for less than six months were excluded. One hundred patients with 124 lung tumors were included in this study. According to our own protocols for SBRT, during the same period, patients with subclinical
Results
The median follow-up period after SBRT was 17.1 months (range, 6.0–71.5 months). Subclinical ILD on the pre-SBRT CT findings was recognized in 16 (16%) of 100 patients: 84 patients with no evidence of ILD (score 0), two patient with a status of slight ILD (score 1), five patients with a status of mild ILD (score 2) and nine patients with moderate ILD (score 3).
Grade 2 or higher RP was recognized in 13 (13%) of 100 patients: Grade 5 in one patient, Grade 4 in one patient, Grade 3 in four
Discussion
Promising clinical results of thoracic SBRT with high local control rates and the absence of severe toxicities have been demonstrated [7], [15]. Recently, thoracic SBRT has been performed as a standard treatment method in patients with medically inoperative NSCLC or those who refuse surgery, especially to treat peripheral lesions. Previous studies of thoracic SBRT have reported a 9–28% incidence of Grade 2 or higher RP [2], [16], [17], [18], [19]. To our knowledge, however, only a few papers
Conflict of interest statement
Potential conflicts of interest do not exist in this study.
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Stereotactic body radiation therapy (SBRT) as salvage treatment for early stage lung cancer with interstitial lung disease (ILD): An observational and exploratory case series of non-asian patients
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2022, Clinical Lung CancerCitation Excerpt :These results are consistent with other published series suggesting that IMPT is safe.47-48 Radiation pneumonitis is a significant dose limiting treatment-related toxicity in locally advanced NSCLC characterized by dyspnea, fever, and cough.49-50 The incidence of grade more than or equal to 3 pneumonitis rate in our study (9.2%) was higher than in the pre-durvalumab RTOG 0617 trial (3.5% with IMRT) and similar to the PACIFIC trial (7.7% with either pneumonia or pneumonitis).