Changes in Pulmonary Function and Development of Clinical Radiation Pneumonitis in Breast Cancer Patients following Post Mastectomy Radiation Therapy

Background: Lung is the main organ at risk for radiation induced injury while treating breast cancers with Post Mastectomy Radiotherapy (PMRT). Restrictive lung changes are usually seen in spirometry which tends to normalize by 1 year. Central Lung Distance (CLD) is shown to correlate well with the percentage of ipsilateral lung volume irradiated. Aims and Objectives: Spirometric changes following Radiation Therapy (RT) to chest wall in breast cancer patients using conventional fractionation and its correlation with acute radiation pneumonitis. Materials and Methodology: Thirty Breast cancer patients who received RT to chest wall +/supraclavicular fossa and axilla, following Modified Radical Mastectomy (MRM) and neoadjuvant or adjuvant chemotherapy using tangential beams with Co60 teletherapy to a dose of 50 Gray in conventional fractionation were included and followed up till 6 months post RT. Baseline chest X-ray and spirometry done pre-RT were compared with those taken at 1, 3 and 6 months after completion of RT. Patients were evaluated at each visit for signs and symptoms of radiation pneumonitis, when present were graded as per Radiation Therapy Oncology Group (RTOG) criteria. Results: There was a significant fall in Forced Vital Capacity (FVC) by the end of 3 months (p value <0.01) which improved by 6 months without any active intervention in 95% of the patients. Mean baseline FVC was 83% which decreased to 70% by the end of 3 months and 79% at 6 months. Forced Expiratory Volume in first second (FEV1) and FEV1/FVC did not show any significant change compared to baseline. Spirometric changes correlated with reversible restrictive lung changes. One out of 30 patients developed symptomatic acute radiation pneumonitis (5%) of grade 3 severity who had moderate restrictive lung disease. Conclusion: Significant decrease in FVC of the lungs is present following PMRT in carcinoma of breast patients in the initial 3 months which tends to normalize by 6 months. 5% of the patients develop symptomatic acute lung toxicity which can be further reduced by minimizing the irradiated lung volume.