الفهرس 
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Abstract
Cancer of the breast is the most common malignancy in women not only in Egypt but also worldwide and represents the main cause of cancer-related death in females. Radiotherapy is a cornerstone in breast cancer management as it decreases local recurrence and improves overall survival. Treating breast cancer patients with adjuvant (post-operative) radiotherapy is considered one of the most common tools in the process of management.
Radiation-induced lung injury is a prominent side effect in patients receiving radiotherapy in the chest region as the lungs are considered one of the main organs at risk due to reported radiation-induced pneumonitis or fibrosis. Decreasing toxicity is the main target of new radiotherapy techniques and updates in radiotherapy.
Pulmonary function tests (PFTs) reveal lung functional changes in patients who may be either symptomatic or non-symptomatic. PFTs provide details about different aspects of lung function and provide information about obstructive and restrictive conditions. Spirometry, as a diagnostic tool, measures the rate of gas movement; the most commonly measured parameters are FEV1 and FVC. Besides measuring lung volumes and capacities, it also presents information about the responsiveness of airways, the influence of disease on lung function, the prognosis of the disease, and response to therapeutic interventions.
Works of literature discussing lung toxicity caused by breast irradiation are very heterogeneous due to different simulation techniques, different treatment planning systems, and different treated sites. Radiation-induced lung toxicity has been investigated in many trials for conventionally fractionated regimens. However, few trials studied the lung toxicity induced by radiotherapy in patients receiving hypofractionated schedules.
The aim of this study is to evaluate the effect of hypofractionated radiotherapy in breast cancer patients on pulmonary functions (spirometry).
This study included 31 breast cancer patients who received hypofractionated post-operative radiotherapy to the chest wall/breast ± regional lymph nodes, with a dose ranging from 40-50 Gy, 5 days a week over 15 fractions by high energy linear accelerator. They were treated at Clinical Oncology and Nuclear Medicine Department, Ain Shams University in the period between September 2020 and October 2021. All patients submitted to full medical and surgical history, general clinical examination, local chest examination, CT chest before the RT, and Spirometry before and 8 weeks after the end of RT in the pulmonary function unit of Ain Shams University Hospitals.
In this study, all patients were with no lung changes before radiotherapy treatment on radiological evaluation of patients using CT. Radiation pneumonitis was assessed clinically by using CTCAE V.5 after 8 weeks of radiotherapy treatment. Twenty-six patients (83.9%) were asymptomatic (grade 1) and 5 patients (16.1%) developed grade 2 toxicity (mild symptomatic RP). No patients experienced grades 3 or 4. Patients with grade 2 received medical treatment with steroids.
Comparative analysis of different baseline spirometric parameters and those obtained 8 weeks after the completion of radiotherapy treatment. There is a highly statistically significant correlation as regards FVC and FEV1 before and after radiation treatment, while FEV1/FVC, FEF25-75%, and FEF50% are not significantly affected. Reduction in FVC and FEV1 without FEV1/FVC suggests acute exudative inflammation in alveoli, favoring restrictive lung injury pattern.
When we correlated different patients and treatment characteristics (age, menopausal state, comorbidity, TN staging, and chemotherapy received) with the percent of change in FEV1 and FVC to assess risk factors that may increase the incidence of RR. We found that there is no statistically significant correlation between any of them and either FVC or FEV1. Investigating the association between the percent of change in FVC and FEV1 and the CTCAE grading system resulted in that FEV1 is more sensitive in predicting RP.