LOS ANGELES—Early data from a Breast Cancer International Research Group (BCIRG) study showed that docetaxel(Drug information on docetaxel) (Taxotere)-based combination therapy was significantly more effective than standard FAC (fluorouracil/doxorubicin [Adriamycin]/cyclophosphamide [Cytoxan, Neosar]) for the treatment of early-stage breast cancer (ASCO abstract 141). Reporting on behalf of BCIRG was its chairman Jean-Marc Nabholtz, MD, professor of medicine at the University of California at Los Angeles and director of Cancer Therapy Development at UCLA’s Jonsson Comprehensive Cancer Center.
The phase III trial compared TAC (Taxotere [docetaxel]/doxorubicin/cyclophosphamide (TAC) to FAC as adjuvant treatment for node-positive breast cancer. Dr. Nabholtz said that interim data analysis with a median follow-up of 33 months showed that TAC reduced breast cancer recurrence risk by 32% (relative risk 0.68 vs FAC, P = .0011) and reduced mortality for women with 1 to 3 positive nodes by 54% (P = .006).
"The observed early benefit that TAC provides over FAC in treatment of node-positive breast cancer is large enough to be of clinical significance, but final conclusions will require a longer period of follow-up," Dr. Nabholtz said.
Relapse Risk Reduced
The primary study endpoint is disease-free survival (DFS), assessed by Cox analysis. This showed a relative risk for TAC/FAC of 0.64 (CI 0.54-0.81, P = .0002). "Seventy-four percent of patients were alive and disease-free at 36 months on FAC and 82% on TAC," Dr. Nabholtz said.
There were 119 recurrences on TAC vs 170 on FAC. This constitutes a 32% reduction in relapse risk (P = .0011), but planned subset analysis showed that this improvement was accounted for entirely by better outcomes for women with three or fewer positive nodes. TAC cut the risk of relapse in half for these women but did not improve DFS for women with four or more positive nodes.
Dr. Nabholtz said the investigators were surprised to find that TAC reduced the risk of relapse almost equally in hormone-receptor positive (HR+) patients and in those who were hormone-receptor negative (32% reduction, P = .002, and 38% reduction, P = .005). "It was very unexpected to see such a difference in a group of patients with positive hormonal receptor status," he said.
