Comparison of Effects of Two Radiotherapy Techniques, Two Tangential / Single Anterior Supra-clavicular Field and Two Tangential / Two Anterior and Posterior Opposed Supra-clavicular Fields on Lung Volumes and Peripheral Oxygen Saturation

Background: Chest wall irradiation for early breast cancer affects forced vital capacity (FVC), forced expiratory volume in the first second of expiration (FEV1) and may change peripheral oxygen saturation (SpO2). In our institute chest wall is irradiated with a four field technique: two tangential and two oppositional anterior and posterior supraclavicular fields. Regional recurrence in this technique is less than 5 percent. Materials and Methods: We conducted this study to compare changes in FEV1, FVC and SpO2 between standard three field and four fields technique.

Materials and methods: We randomized 51 stage I and II breast cancer cases after modified radical mastectomy and completion of chemotherapy in two groups. In group I patients were treated with four field and in group II with three field technique using cobalt 60 teletherapy. Patients with a history of smoking, pulmonary disease, heart disease and any deformities in chest wall were excluded. Patients were stratified due to central lung distance (CLD), fields separation in tangential fields and filed borders defined in standard manner. Radiotherapy dose was 50.4 Gy in 28 fractions. Spirometry and pulse oxymetry was done before, one month after and three months after the completion of radiotherapy.

Results: FEV1, FVC and FEV1/FVC showed no significant difference between two groups one month and three months after radiotherapy. Also there was no significant difference in FEV1, FVC, FEV1/FVC one month after radiotherapy comparing with pre-radiotherapy values. There were significant differences in FEV1 and FVC reduction three months after radiotherapy in comparison with preradiotherapy values (P<0.001, P<0.006 respectively). SpO2 showed no significant difference between two groups and also in each group after one and three months.

Conclusion: Locoregional radiotherapy of chest wall and supraclavicular lymph nodes causes reduction in FEV1 and FVC three months after radiotherapy but there is no significant difference between three field and four fields techniques. We suggest this study be completed by using pulmonary function tests including spirometry and diffusion capacities.