Author(s)

Yukinori Okada^1*, Shingo Sakamoto¹, Tatsuyuki Abe¹, Mio Shinozaki¹, Hiromichi Gomi¹, Yoshihide Kanemaki², Shin Matsuoka¹, Yasuo Nakajima¹

¹Department of Radiology, St. Marianna University School of Medicine, Kawasaki, Japan.
²Department of Radiology, Breast and Imaging Center, St. Marianna University School of Medicine, Kawasaki, Japan.

We investigated the factors predicting radiation-induced organizing pneumonia (RIOP) relapse after tangential breast irradiation. The participants included 23 patients diagnosed with RIOP at the St. Marianna University School of Medicine Hospital between January 2008 and March 2015. Relapse was defined as the appearance of new lesions on diagnostic images during follow-up or after commencing treatment. The relapse-free survival rate and the following 9 parameters were compared between patients with and without RIOP relapse: 1) age (less than vs. equal to or more than the median); 2) white blood cell count (less than vs. equal to or more than the median); 3) C-reactive protein (CRP) level at the time of RIOP diagnosis (less than normal, more than normal/ less than borderline, and more than borderline); 4) boost irradiation (yes vs. no); 5) maximum lung depth on linacgraphy (less than vs. equal to or more than the median); 6) hormone therapy (yes vs. no); 7) chemotherapy (yes vs. no); 8) RIOP ratio in the whole lung (less than vs. equal to or more than the median) at the time of RIOP diagnosis; and 9) use of corticosteroids (yes vs. no). The Kaplan-Meier method was used for statistical analysis, with relapse as the cutoff. The follow-up period spanned the date of RIOP onset to May 30, 2015. The level of significance for 2-sided tests was p < 0.05. Relapse was evident in 14 patients (60.8%). The relapse-free survival rate was significantly greater in the normal CRP group (less than 0.30 mg/dl) than in the abnormal CRP group (more than 0.36 mg/dl) (p = 0.044) and in the normal/borderline CRP group (less than 0.36 mg/dl) than in the high CRP group (more than 0.70 mg/dl) (p < 0.01). The CRP level at RIOP onset may be a useful predictor of relapse after breast-conserving therapy.We investigated the factors predicting radiation-induced organizing pneumonia (RIOP) relapse after tangential breast irradiation. The participants included 23 patients diagnosed with RIOP at the St. Marianna University School of Medicine Hospital between January 2008 and March 2015. Relapse was defined as the appearance of new lesions on diagnostic images during follow-up or after commencing treatment. The relapse-free survival rate and the following 9 parameters were compared between patients with and without RIOP relapse: 1) age (less than vs. equal to or more than the median); 2) white blood cell count (less than vs. equal to or more than the median); 3) C-reactive protein (CRP) level at the time of RIOP diagnosis (less than normal, more than normal/ less than borderline, and more than borderline); 4) boost irradiation (yes vs. no); 5) maximum lung depth on linacgraphy (less than vs. equal to or more than the median); 6) hormone therapy (yes vs. no); 7) chemotherapy (yes vs. no); 8) RIOP ratio in the whole lung (less than vs. equal to or more than the median) at the time of RIOP diagnosis; and 9) use of corticosteroids (yes vs. no). The Kaplan-Meier method was used for statistical analysis, with relapse as the cutoff. The follow-up period spanned the date of RIOP onset to May 30, 2015. The level of significance for 2-sided tests was p < 0.05. Relapse was evident in 14 patients (60.8%). The relapse-free survival rate was significantly greater in the normal CRP group (less than 0.30 mg/dl) than in the abnormal CRP group (more than 0.36 mg/dl) (p = 0.044) and in the normal/borderline CRP group (less than 0.36 mg/dl) than in the high CRP group (more than 0.70 mg/dl) (p < 0.01). The CRP level at RIOP onset may be a useful predictor of relapse after breast-conserving therapy.

Radiation-Induced Organizing Pneumonia, Breast-Conserving Therapy, Tangential Irradiation, C-Reactive Protein

Okada, Y. , Sakamoto, S. , Abe, T. , Shinozaki, M. , Gomi, H. , Kanemaki, Y. , Matsuoka, S. and Nakajima, Y. (2015) Factors Predicting the Relapse of Radiation-Induced Organizing Pneumonia after Breast-Conserving Therapy. Open Journal of Radiology, 5, 159-169. doi: 10.4236/ojrad.2015.53023.