Adjuvant therapy for HER2+ breast cancer: practice, perception, and toxicity

Multiple adjuvant regimens are used for HER2+ breast cancer, but experience in routine practice is not reported. We evaluated whether oncologists' perceptions of these regimens matches clinical experience. We surveyed Wisconsin medical oncologists throughout the state regarding factors impacting selection of TCH (docetaxel, carboplatin, and trastuzumab) or anthracycline-based therapy. We also reviewed 200 cases of HER2+ breast cancer treated at the University of Wisconsin and the Marshfield Clinic and collected data on patient and tumor characteristics, chemotherapy regimen, and toxicities. Two-thirds of surveyed oncologists prefer anthracycline-based therapy, particularly for node-positive cancers. However, TCH was preferred for early-stage (T1a-bN0) tumors. Half of oncologists use prophylactic G-CSF with TCH. In the 200 cases reviewed at our centers, acute toxicity occurred more frequently with TCH. There were fewer dose modifications or delays for AC-TH (doxorubicin, cyclophosphamide, paclitaxel, and trastuzumab) than TCH (31% vs. 47%, P = 0.07), possibly due to higher use of prophylactic G-CSF with AC-TH (77% vs. 34% with TCH, P < 0.001). Fifteen patients received prophylactic G-CSF during TCH; none developed neutropenic fever. In contrast, 25% developed neutropenic fever during TCH without G-CSF. There were modest declines in median left ventricular ejection fraction reaching 9% with AC-TH and 3% with TCH at 12 months, but early cessation of trastuzumab was similar for both regimens. We conclude that TCH and AC-TH are common adjuvant regimens used for HER2+ breast cancer. The preference of TCH for early-stage disease and anthracycline-based therapy for node-positive disease suggests that many oncologists perceive that TCH is safer and AC-TH more effective. Myelosuppression from TCH is greater than AC-TH, but can be mitigated with routine G-CSF.