Radiation therapy


The sequence of treatments (chemotherapy and/or surgery and/or radiotherapy) follows a specific timing. Radiation therapy is generally administered in 25 sessions (i.e. 5 sessions per week from Monday to Friday, for 5 weeks).

The sequence of treatments follows a specific timing. If chemotherapy is not required, radiation therapy is usually performed within 12 weeks after surgery. If chemotherapy is required after surgery, radiation therapy will be scheduled 4 to 6 weeks after chemotherapy.

Radiation therapy is usually given in 25 sessions (5 sessions per week, from Monday to Friday, during 5 weeks) to the entire breast. This may be followed by 8 additional sessions of radiation to the initial tumor area, called a “boost”, for a total of 33 sessions. Currently, the treatment is often delivered in 15-20 sessions over 3-4 weeks (“hypo-fractionated” scheme).

As with any radiotherapy treatment, the first step is to perform a simulation CT scan during which the radiation oncologist will determine the treatment field (the entire mammary gland or chest wall +/- the supra- and sub-clavicular, internal mammary and axillary lymph node areas). Small tattoo points will be made at the end of this scan to serve as marks to maintain the correct positioning  during the entire treatment. Breast radiotherapy can be performed using the 3D conformal technique or intensity modulation, depending on the patient’s anatomy and the volumes to be treated (breast alone or with lymph nodes). In some centers, the treatment can be performed in deep inspiration breath-hold for patients with left breast cancer, to reduce the dose received by the heart.