Quality assurance procedures in radiotherapy of breast cancer

In breast cancer, the multidisciplinary therapeutic approach is most commonly used. Radiotherapy, involving neoplastic targets and healthy tissue tolerance already modified by other treatments, in the various phases is burdened with problems and uncertainties which condition treatment quality. Within the four phases of prescription, planning, implementation and follow-up, the authors analyze some uncertainties that impact on the quality of radiation treatment complementary to conservative surgery.

it is the phase where the radiotherapist defines the target volume and the dose to be delivered. Uncertainties remain in CTV2 definition (boost); the not frequent placement of metal clips within the surgical cavity and the not perfect correlation between surgical scar and tumor bed, make their identification not always ready. Moreover, the combination with other therapies creates problems also in dose prescription.

in CTV1 treatment (breast) particular precautions are necessary to decrease the dose contribution at the pulmonary level and avoid that the breast advances towards the supraclavicular region in the supine position. For CTV2, the interstitial boost is indicated especially in patients with a large breast and deep cancer and in cases of non radical surgery, while external beam boost, most commonly used, is performed with electron beams including the pectoral fascia in the 90% isodose.

to prevent or limit the incidence of possible random and/or systematic errors during treatment, suitable procedures are required.

it enables the assessment of therapeutic results in terms of efficacy and side-effects. Some controversies still remain on implementation modalities: intensive vs clinical.