Statement: The Trastuzumab arm of the primary trial reported a pCR rate of 54%, significantly worse results than the Lapatinib arm which achieved a pCR rate of 45%.
Primary_evidence: Outcome Measurement:    Percentage of Participants With Overall Pathological Complete Response (pCR) After 26 Weeks of Therapy   A pCR in the breast was defined as no pathologic evidence of invasive disease (residual ductal carcinoma in situ [DCIS] or lobular carcinoma in situ [LCIS] was allowed). A pCR in the axillary lymph node(s) was defined as no evidence of breast cancer cells in the lymph node (including subcapsular sinus). Overall pCR was defined as the sum of pCR in the breast and pCR in the lymph nodes. 26 weeks of therapy comprised the 2-week run-in phase, 12 weeks of treatment with FEC, and 12 weeks of treatment with Paclitaxel.   Time frame: Week 26 Results 1:    Arm/Group Title: Trastuzumab   Arm/Group Description: Participants received trastuzumab alone (a loading dose of 4 milligrams [mg]/kilogram [kg] on Day 1, followed by a dose of 2 mg/kg on Day 1 of Week 2 and weekly thereafter). Participants were treated with trastuzumab in a 2-week run-in period. On Day 14, a second core needle biopsy was performed, followed by initiation of chemotherapy with 2 combination regimens of 4 cycles each (1 cycle=3 weeks): FEC75 (5-fluorouracil [5-FU] 500 mg/meters squared [m^2], epirubicin 75 mg/m^2, cyclophosphamide 500 mg/m^2 x 4 cycles on Day 1), then paclitaxel (80 mg/m^2 x 4 cycles on Day 1, Day 8, and Day 15) in combination with trastuzumab.   Overall Number of Participants Analyzed: 26   Measure Type: Number   Unit of Measure: percentage of participants  54.0 Results 2:    Arm/Group Title: Lapatinib   Arm/Group Description: Participants received lapatinib alone (1250 mg orally [PO] once daily [QD]). Participants were treated with lapatinib in a 2-week run-in period. On Day 14, a second core needle biopsy was performed, followed by initiation of chemotherapy with 2 combination regimens of 4 cycles each (1 cycle=3 weeks): FEC75 (5-FU 500 mg/m^2, epirubicin 75 mg/m^2, cyclophosphamide 500 mg/m^2 x 4 cycles on Day 1), then paclitaxel (80 mg/m^2 x 4 cycles on Day 1, Day 8, and Day 15) in combination with lapatinib.   Overall Number of Participants Analyzed: 29   Measure Type: Number   Unit of Measure: percentage of participants  45.0