Statement: the primary trial has a 5 year long intervention, the duration of the secondary trial is not specified in the intervention section.
Primary_evidence: INTERVENTION 1:    Tamoxifen   Tamoxifen 20mg orally daily for 5 years INTERVENTION 2:    Ovarian Function Suppression   Tamoxifen 20mg orally daily or Exemestane 25mg orally daily for 5 years plus ovarian function suppression (OFS; triptorelin (GnRH analogue) 3.75 mg by im injection q28 days for 5 years; or surgical oophorectomy; or ovarian irradiation)   Note: Data were collected separately for the T+OFS and E+OFS participants in the parent study, IBCSG 24-02 (SOFT). The sample size for this Co-SOFT substudy was small, so the analysis plan was revised to pre-specify collective analysis for all patients receiving OFS.
Secondary_evidence: INTERVENTION 1:    Single Drain   Insertion of a single drain: A negative pressure drain will be inserted below the lower flap directing to the axilla in the single drain group.   Ultrasonography after removal of the drains: One day after removal of the drains seroma under the flaps and in the axilla will be examined by ultrasonography.   Insertion of a single drain: A negative pressure drain will be inserted below the lower flap directing to the axilla.   Ultrasonography after removal of the drains: One day after removal of the drains seroma under the flaps and in the axilla will be examined by ultrasonography. INTERVENTION 2:    Double Drain   Insertion of double drains: Two negative pressure drains will be inserted into the axilla and below the lower flap in the double drains group.   Ultrasonography after removal of the drains: One day after removal of the drains seroma under the flaps and in the axilla will be examined by ultrasonography.   Insertion of double drains: Two drains will be inserted into the axilla and below the lower flap in the double drains group.   Ultrasonography after removal of the drains: One day after removal of the drains seroma under the flaps and in the axilla will be examined by ultrasonography.