(CHICAGO, IL) – Maintenance chemotherapy with the combination of gemcitabine and paclitaxel (GP) following clinical response to GP is associated with improved survival times among metastatic breast cancer patients without impairing patient quality of life, according to results of a Phase 3 clinical trial presented at the 2012 American Society of Clinical Oncology Annual Meeting.

The prospective, randomized, multicenter study was intended to clarify the optimal duration of chemotherapy for metastatic breast cancer, which remains controversial, said lead author Young-Hyuck Im, MD, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea. The study also aimed to determine if GP is superior to observation in terms of progression-free survival (PFS) in responding patients with metastatic breast cancer after 6 cycles of GP as first-line treatment. The study was conducted at 10 cancer centers by the Korean Cancer Study Group between 2007 and 2010.

Metastatic breast cancer patients who achieved complete or partial response, or stable disease, after 6 cycles of GP chemotherapy (gemcitabine 1,250mg/m2 on Day 1 and 8, plus paclitaxel 175mg/m2 on Day 1 every 3 weeks) were randomly assigned either to a maintenance-until-progression arm or an observation arm

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At a median follow-up period of 33 months, median PFS was significantly longer among 116 patients in the GP maintenance-arm than the 115 patients assigned to the observation control group, 12.0 vs. 8.3 months; HR 0.73 (95% CI: 0.55–0.97); P=0.031. From randomization, median PFS was 7.5 months in the maintenance arm vs. 3.8 months in the observation arm (adjusted HR 0.73 [95% CI: 0.55–0.96]; P=0.026). Median 6-month PFS rate was 59.7% in the GP maintenance arm vs. 36% in the observation arm (P=0.00023).

Although these data are preliminary, median overall survival (OS) was significantly prolonged among patients receiving maintenance therapy compared with those in the observation group, 36.8 vs. 28.0 months; HR 0.65 (95% CI: 0.42–0.99); P=0.048).

No impairment in quality of life was observed in the maintenance GP arm, Dr. Im said. He concluded by noting that maintenance GP chemotherapy after 6 cycles should be considered in patients with metastatic breast cancer who have negative hormone receptor tumors, visceral disease, high tumor burden, are aged 50 years or younger, or are premenopausal.