TAC Regimen Superior to FAC for Early Breast Cancer

Jane Salodof MacNeil

December 08, 2003

Dec. 8, 2003 (San Antonio) — Adjuvant chemotherapy with docetaxel reduced the risk of death from node-positive early-stage breast cancer by 30% at 55 months of follow-up in a major phase III trial.

The combination of docetaxel (Taxotere), doxorubicin (Adriamycin), and cyclophosphomide (Cytoxan) (TAC) also cut the risk of relapse by 28% compared with the standard three-drug regimen of 5-fluorouracil, doxorubicin, and cyclophosphomide (FAC).

"Three hundred thousand women are diagnosed every year with node-positive breast cancer. If they receive TAC, five years from now 18,000 women will be alive because of the new treatment," investigator John R. Mackey, MD, said today at a press briefing here before presenting the results during a special late-breaker session at the 26th Annual San Antonio Breast Cancer Symposium.

The study found that TAC has "major clinical value in adjuvant treatment of women with early stage node positive breast cancer," said Dr. Mackey, a medical oncologist at the University of Alberta and Cross Cancer Institute in Edmonton, Canada.

The Breast Cancer International Research Group (BCIRG) conducted the trial known as BCIRG 001. The randomized study enrolled 1,491 women in 20 countries from June 1997 to June 1999. The new data are based on 55-month follow-up from 92% of participants.

Disease-free survival reached 75% for the women receiving TAC vs. 68% for those receiving FAC. This translated into a hazard ratio of 0.72 (P = .0010).

Overall survival at five years was 81% for the FAC cohort compared with 87% for the women receiving TAC (hazard ratio, 0.70; P = .0080).

Subgroup analyses showed relapse rates decreased 27% in estrogen receptor–positive women and 34% in those who were estrogen receptor–negative. While women with one to three nodes fared better than those with four or more, both benefited; the hazard ratios were 0.61 (P = .0009) for the former and 0.82 (P = .1629) for the latter.

Patients with HER2-neu amplification also did better on TAC. The hazard ratio for HER2-positive patients receiving TAC was 0.61 (P = .0118) and for HER2-negative patients it was 0.76 (P = .0380).

"We can't pick out a group that is not benefiting from the new treatment," Dr. Mackey said.

Febrile neutropenia was significantly higher in the TAC arm (24.7% vs. 2.5%). Dr. Mackey noted that patients were not given prophylactic growth factors, however. "It is safe," he said.

According to I. Craig Henderson, MD, from the University of California at San Francisco, the trial did not answer the most important question for patients and oncologists — ie, which is the best treatment — because it did not include a group receiving dose-dense therapy. Nonetheless, it did establish the superiority of TAC over FAC, he told Medscape.

"FAC is a regimen we've used for 20 years and clearly has been one of our best regimens. TAC clearly represents an improvement. There's no question about that," Dr. Henderson said.

The study received support from Aventis, the maker of docetaxel.

26th Annual SABCS: Abstract 43. Presented Dec. 5, 2003.

Reviewed by Gary D. Vogin, MD


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