[Dosimetric and clinical benefits of respiratory-gated radiotherapy for lung and breast cancers: results of the STIC 2003]

Abstract

Purpose: To compare respiratory-gated conformal radiotherapy versus conventional conformal radiotherapy for the irradiation of non-small cells lung cancer and breast cancer.

Patients and methods: The STIC 2003 project was a comparative, non-randomized, multicenter and prospective study that included in 20 French centers between April 2004 and June 2008, 634 evaluable patients, 401 non-small cells lung cancer and 233 breast cancers.

Results: The final results confirmed the feasibility and good reproducibility of the various respiratory-gated conformal radiotherapy systems regardless of tumour location. The results of this study demonstrated a marked reduction of dosimetric parameters predictive of pulmonary, cardiac and esophageal toxicity, especially for non-small cells lung cancer, as a result of the various respiratory gating techniques. These dosimetric benefits were mainly observed with deep inspiration breath-hold techniques (ABC and SDX), which markedly increased the total lung volume compared to the inspiration-synchronized system based on tidal volume (RPM). For non-small cells lung cancer, these theoretical dosimetric benefits were correlated with a significant reduction in clinically acute and late toxicities, especially the pulmonary. For breast cancer, although less clear due to the lower total dose, there was a decrease in the dose delivered to the heart, potentially reducing the risk of cardiac toxicity in the long-term, especially during the irradiation of the left breast, and a reduction in dose to the contra lateral breast.

Conclusion: Respiratory-gated radiotherapy appears to be essential to reduce the risk of acute and late toxicities, especially for lungs and heart, during irradiation of non-small cells lung cancer and breast cancers.