Systemic Inflammation-Immune Status Score Predicts the Incidence of Radiation Induced Pneumonitis in Patients With Breast Cancer After Whole Breast Irradiation: A Result From Two Medical Centers.

Abstract

PURPOSE/OBJECTIVE(S)\nRadiation induce pneumonitis (RP), is a common adverse event after thoracic radiotherapy in patients with breast cancer. The biologically predictive marker of RP in breast cancer is not so abundant as that in lung cancer. Systematic inflammation-immune status (SIS) has been thought to play a crucial role in tumorigenesis, prognosis, and inflammation. Therefore, we proposed this study to evaluate the association between systematic inflammation-immune status and the incidence of RP in patients with breast cancer after whole breast irradiation.\n\n\nMATERIALS/METHODS\nWe searched cases of patients treated at the two institutions, between January 1 2018 and December 31 2018. Inclusion criteria included: pathologically confirmed breast cancer and received breast conserving surgery as the first treatment; patients received postoperative whole breast irradiation; intensity modulated radiotherapy or volumetric modulated arc therapy is delivered to; available blood counts before the radiation and within 1 months from the accomplishment of radiation, available CT scan within one year from the accomplishment of radiotherapy. Pre-radiation and post-radiation inflammation-immune status score were calculated using the formula Platelet X Neutrophil/Lymphocyte. Radiation induced pneumonitis was evaluated by a senior radiation oncologist and a senior radiologist according to CTC AE 4.0. Training group included half of the patients from one center and validation group included the other half of the patients as well as patients from the other center. Receiver operating characteristic (ROC) curve analysis is utilized to define the cut-off value of SIS in affecting RP development.\n\n\nRESULTS\nTotally, 562 patients fulfilled the eligibility criteria. The predictive model was built based on data of 232 patients and validated by 330 patients. After ROC analysis, cut off value was 482.98*109 and 895.32*109 at the time of pre-radiation and post-radiation, respectively. According to the cutoff value of pre-radiation SIS, patients were divided into PrLIS group (pre-radiation SIS≤482.98*109) and PrHIS group (pre-radiation SIS > 482.98*109). Similarly, according to the cutoff value of post-radiation SIS, patients were divided into PoLIS group (post-radiation SIS≤895.32*109) and PoHIS group (post-radiation SIS > 895.32*109). The validation showed that there is no significant difference of RIP (56.1% vs.60.1%, P\u202f=\u202f0.455) between patients in PrLIS and PrHIS group. Patients in PoHIS group were more likely to get RP than that in PoLIS group (72.7% vs 54.5%, P\u202f=\u202f0.001) CONCLUSION: The post radiation SIS is a sensitive predictor of RP in patients with breast cancer after whole breast irradiation. For patients with high SIS after radiation, CT scan after radiation might be taken into consideration.