STUDY OF EARLY RADIATION PNEUMONITIS IN CARCINOMA BREAST AND LUNG TREATED WITH RADIOTHERAPY

Introduction: Radiation induced Pulmonary toxicity is common after radiation therapy (RT) to the thorax. Breast Cancer is one of the commonest cancers requiring chest wall irradiation. The quantification of lung tissue response to irradiation is important in designing treatments for maximum tumor control. Objective: To study the impact of lung volume irradiated on early pneumonitis in patients undergoing RT for breast cancer. Method: The Study was conducted as per ICH GCP guidelines and with Ethics Committee approval. This is prospective study of 26 patients with breast cancer treated with radiotherapy to the chest wall. Computerized tomography (CT) simulation was part of treatment planning. The volume of lung irradiated was calculated by using both CLD (Central Lung Distance) method and summation of area technique. Chest x-ray and spirometric tests were done first as a baseline procedure and later at one month and at 3 months after completion of radiotherapy. Results: The incidence of acute radiation pneumonitis in carcinoma breast is 3.9%. With conventional technique of treatment planning for carcinoma breast, percentage of lung volume irradiat ed in majority of cases (16/26) was within 11% and CLD proved to be best predictor of it. The total dose of 45-50 Gy with conventional fractionation and dose/Fr of 180-200 cGy is safer. Conclusion: The spirometry is helpful in assessing the radiation damage of lung. The CLD method of calculation of PIV (Percentage of Irradiated Lung Volume) is recommended.