The adjuvant radiotherapy to the whole breast or the chest wall is an integral part of the treatment of breast cancer. This study is aimed at evaluating the potential for sparing the heart and lung using voluntary deep inspiratory breath-hold (DIBH) technique for radiotherapy of left sided breast or chest wall.
During the period 09.2016 – 09.2017, 95 patients with breast cancer had planning CT scans in the both respiratory phases, using Varian Real Time Positioning Management System® for monitoring of the respiratory chest wall excursions. Each patient had two planning CT scans: one during free breathing (FB) and another one with voluntary deep inspiration breath-hold (DIBH). The Planning Target Volume (PTV) included the whole breast/chest wall with or without the supraclavicular nodal groups (SCL). For each patient, two radiotherapy plans were prepared using the FB and the DIBH planning scans.
The DIBH was very well tolerated. The mean anterior-posterior chest wall shift during FB was 3.1 mm. With the DIBH, the front chest wall position was between 10 mm and 18 mm anteriorly to its mid-FB position. In the post-lumpectomy cases the portion of the heart that received more than 50% of the prescribed dose, was decreased from 2.07% to 0% (39.7 % max dose). At the same time, relative lung volume irradiated to > 50% of the prescribed target dose was reduced from 17.63% (for FB) to 13.2% (for DIBH). In one extreme case with SCL, the volume of the heart, receiving more than 50% of the prescribed dose, was: 5.74% for FB and 0% for DIBH (36% max dose); the ipsilateral lung received: 21.2% with FB and 8% with DIBH. The median ipsilateral relative lung volume receiving >50% was higher for DIBH – 14.17% and 10.91% for FB.
This is the first study in Bulgaria, which demonstrates the dosimetric benefits of breathing adapted radiotherapy (BART). Our results showed that irradiated cardiac volumes can be consistently reduced for left-sided breast cancers by using DIBH.
Has not received any funding.
All authors have declared no conflicts of interest.