Stage I, II, IIIA, and Operable IIIC Breast Cancer
At 3 years, of all of the patients, 71% (95% CI, 61-78) showed improvement in EFS with trastuzumab versus 56% without trastuzumab (95% CI, 46-65), HR = 0.59 (95% CI, 0.38-0.90, P = .013), thereby favoring the addition of trastuzumab. The 3-year OS was 87% versus 79% at the time of the report (P = .114, not significant). Symptomatic cardiac failure developed in two patients receiving concurrent doxorubicin and trastuzumab for two cycles. Close cardiac monitoring of left ventricular ejection fraction (LVEF) and the total dose of doxorubicin not exceeding 180 mg/m2 accounted for the relatively low number of declines in LVEF and only two cardiac events. (See the Cardiotoxicity with adjuvant trastuzumab section in this summary.)[Level of evidence: 1iiD]
Adjuvant radiation and chemotherapy
The optimal sequence of adjuvant chemotherapy and radiation therapy after breast-conserving surgery was studied in a randomized trial. Patients received either chemotherapy first (n = 122), consisting of CMFP plus doxorubicin repeated every 21 days for four cycles, followed by breast radiation, or breast radiation first (n = 122), followed by the same chemotherapy. With a median follow-up of 5 years, OS was 73% for the radiation-first group and 81% for the chemotherapy-first group (P = .11).[Level of evidence: 1iiA] The 5-year crude rates of first recurrence by site in the radiation-first and chemotherapy-first groups, respectively, were 5% and 14% for local recurrence and 32% and 20% for distant or regional recurrence or both. This difference in the pattern of recurrence was of borderline statistical significance (P = .07). Further analyses revealed that differences in recurrence patterns persisted for most subgroups with the exception of those that had either negative tumor margins or one to three positive lymph nodes. For these two subgroups, sequence assignment made little difference in local or distant recurrence rates, though the statistical power of these subgroup analyses was low. Potential explanations for the increase in distant recurrence noted in the radiation therapy-first group are that chemotherapy was delayed for a median of 17 weeks after surgery, and that this group received lower chemotherapy dosages due to increased myelosuppression.
Two additional randomized trials, though not specifically designed to address the timing of radiation therapy and adjuvant chemotherapy, do add useful information.[165,217] In the NSABP-B-15 trial, patients who had undergone breast-conserving surgery received either one course of CMF (n = 194) followed by radiation therapy followed by five additional cycles of CMF, or they received four cycles of AC (n = 199) followed by radiation therapy. No differences in DFS, distant DFS, and OS were observed between these two arms.[Level of evidence: 1iiA] The International Breast Cancer Study Group trials VI and VII also varied the timing of radiation therapy with CMF adjuvant chemotherapy. These studies showed that delays from 2 to 7 months in radiation therapy after surgery had no effect on the rate of local recurrence.