T-staging and target volume definition by imaging in breast tumours

Abstract

Breast cancer is the most frequent cancer in women in both developed and developing countries. Early detection of breast cancer is of great importance, as it allows carrying out less mutilating or aggressive treatments, thus achieving a better quality of life and higher survival rates. The standard of care in breast cancer therefore includes organized screening programs. Mammography and MRI play a key role in both staging of breast lesions and target volume definition. The treatment of breast cancer should be multidisciplinary, involving gynecologists, pathologists, radiologists, surgeons, medical oncologists, and radiation oncologists and nuclear medicine physicians, among others, in order to personalize the treatment of each patient. With the aim of offering the best radiation therapy to patients, but in turn to limit radiation to organs at risk, several imaging techniques are used, which help to define the volumes of treatment: clinical tumour volume (CTV) and planning tumour volume (PTV). Throughout the world, computed tomography (CT) is the most used imaging technique for treatment planning, but we can use the information provided by ultrasound, magnetic resonance, etc., to assist in correctly defining the primary tumour bed and the lymph node regions. Radiation therapy is adapted to the patients’ risks and may include whole-breast, chest wall, regional nodes, or be limited to (accelerated) partial breast irradiation ((A)PBI). Regarding [18F]FDG PET/CT, it has a limited role in the diagnosis of breast cancer, but it can provide relevant information for detecting locoregional and distant disease, for helping to plan surgical and medical treatment, monitoring response, and locating recurrent disease. PET also has the potential to quickly assess new treatments by detecting their effects on specific receptors and has evidenced it improves the prediction of the clinical outcome in previously treated breast cancer patients.