Hypofractionated vs Standard Radiotherapy in Breast Cancer With an Indication for Regional Lymph Node Irradiation About Lymphedema Occurrence

Inclusion Criteria:

* Woman ≥ 18 years who had radical surgery for invasive breast cancer pT1-3, pN0-N3, M0 with either mastectomy or breast conservation. The patient can be included no matter the status of oestrogen receptor, progesterone receptor, malignancy grade, HER2 status.
* ECOG 0-2
* Axillary lymph node dissection of the axilla where the findings give indication for regional nodes radiotherapy to levels +/-I, +/- II, +/-III, +/-IV, +/-interpectoral nodes (Rötter) and +/-the IMN.
* Sentinel node biopsy documenting limited nodal disease without an indication for axillary lymph node dissection according to institutional, national or other trial guidelines are accepted.
* The patient may be a candidate for a boost to the tumour bed.
* Adjuvant systemic therapy with chemotherapy, endocrine therapy and anti-HER2 treatment is accepted.
* Neoadjuvant chemotherapy for downstaging according to institutional or national guidelines is accepted if there is not an indication for a boost in the area of regional nodes after surgery.
* Primary systemic therapy of an operable breast cancer is accepted.
* If the patient is not treated with chemotherapy, the patient must be randomized within 8 weeks from last surgery. If the patient has received adjuvant chemotherapy, the patient must be randomized within 4 weeks after the last series of adjuvant chemotherapy or within 42 days from last surgery in case of surgery after neoadjuvant or adjuvant chemotherapy.Breast implants are accepted.
* Connective tissue disease is allowed if the treating radiation oncologist finds radiotherapy indicated
* Postoperative infection and/or seroma giving indication for drainage during RT is accepted
* Women of childbearing potential must agree to use adequate contraception for the duration of study participation and up to 3 months following completion of therapy
* Signed informed consent
* Affiliated to the Social Security system

Exclusion Criteria:

* Previous breast cancer or DCIS of the breast.
* Bilateral breast cancer
* Patient with previous non-breast malignancy with the exception of cancer in complete remission for over 5 years and low risk of recurrence. Patients with the following diseases can be accepted despite less than 5 years disease free interval: carcinoma in situ of the cervix, melanoma in situ, basal cell carcinoma of the skin, squamous cell carcinoma of the skin
* The patient has an indication for boost to 1 or more regional nodes
* Previous radiotherapy to the chest region
* Patient enrolled in another therapeutic trial. Observational cohorts are accepted if the collection of data does not interfere with the current trial
* Pregnant or lactating
* Conditions indicating that the patient cannot go through the radiation therapy or follow up, or a condition where the treating radiation oncologist thinks the patient should not participate in the trial for example due to language problems.