Assessment of vital organ dose in volumetric intensity modulated arc therapy for left and right breast cancer

Breast cancer (BC) is a global threat to women’s health. Volumetric intensity modulated arc therapy (VMAT) is effective for the local control of BC. This study evaluated the pulmonary and cardiac radiotherapeutic dosage to provide information for estimating normal tissue complication probability (NTCP) once malignant tumors appear in patients’ left and right breasts.

We conducted a retrospective analysis of VMAT regimen of 40 patients with BC, among whom 20 patients (group 1) were diagnosed with right BC and 20 patients (group 2) with left BC. The pulmonary and cardiac dose volume histogram (DVH) parameters were acquired and compared between patients with left and right BC treated with VMAT.

Generally, the pulmonary and cardiac dosages in patients with right BC were larger than in those with left BC. For the lung, the V20 and V5 of right BC patients were significantly higher, relative to the left BC patients (P<0.05). For the heart, the V5 and V10 of right BC patients were significantly lower, compared to left BC patients, with differences of up to 20% and 10%, respectively (both P<0.05). V20, V30, and V40 as low as zero were observed for right BC patients.

When treating left BC, image guidance and respiratory management techniques should be applied to limit radiotherapy complications that occur in the heart because of patient positioning and respiratory movement.