Contouring of the left anterior descending coronary artery in patients with breast cancer – the radiation oncologist’s view

Breast cancer is the cancer with the largest prevalence, both in Poland and worldwide. The standard treatment in patients with this disease is breast-conserving therapy (BCT), followed by whole breast radiotherapy (WBRT) with a boost dose applied to the area of the bed created after tumour resection. In women who have undergone breast amputation – in the presence of poor prognostic factors – the chest wall is irradiated with or without the irradiation of the axillary fossa and clavicular area. Radiotherapy is used as an adjuvant treatment in connection with the high rate of relapses in the area of the treated breast – as much as 20% after 10 years. Some patients, before the commencement of the irradiation, are treated systemically with the use of regimens comprising drugs with a high degree of cardiotoxicity. This effect may even be increased during the course of radiotherapy – mainly in patients after amputation of the left breast. The side-effects induced by radiotherapy depend on area of the heart within the field of irradiation. Studies suggest that the vulnerable parts of the heart are the coronary vessels, and primarily, the left anterior descending (LAD) artery, which is located close to the chest wall. The objective of this study is to present practical guidelines concerning contouring the left anterior descending (LAD) artery in patients with cancer of the left breast, who have qualified for radiotherapy. Contouring the LAD seems to be significant as a method of assessing the critical organ during radiotherapy. The results may cause a modification of the treatment strategy: a change to the planned radiotherapy, the quantity of the beams and/or their angle of incidence or a change in the beam weight.