Limited M1 disease: a significant prognostic factor for stage IV breast cancer.

PURPOSE: The prognosis of patients with breast cancer presenting with distant metastasis can vary depending on disease extent. This study evaluates a definition of limited M1 disease in association with survival in a cohort of women presenting with metastatic breast cancer. METHODS: The study cohort comprised 692 women referred to the BC Cancer Agency between 1996 and 2005 with M1 breast cancer at presentation. Limited M1 disease was defined as <5 metastatic lesions confined to one anatomic subsite. Extensive M1 disease was defined as ≥ 5 lesions or disease in more than one subsite. Clinicopathologic and treatment characteristics and overall survival (OS) were compared between subjects with limited (n = 233) versus extensive (n = 459) M1 disease. Multivariable analysis was performed by Cox regression modeling. RESULTS: Median follow-up time was 1.9 years. Five-year Kaplan-Meier OS was significantly higher in patients with limited compared to extensive M1 disease (29.7 vs. 13.1 %, p < 0.001). In the multivariable Cox regression analysis, limited M1 disease was significantly associated with OS (hazard ratio 0.51, 95 % confidence interval 0.40-0.66, p < 0.001). The only patient subsets with limited M1 disease with poor 5-year OS <15 % were patients with Eastern Cooperative Oncology Group performance status of ≥ 2 or estrogen receptor-negative status. CONCLUSIONS: Limited M1 disease, defined as <5 metastatic lesions confined to one anatomic subsite, is a relevant favorable prognostic factor in patients with stage IV breast cancer. This definition may be used in conjunction with other clinicopathologic factors to select patients for more aggressive systemic and locoregional treatments.

Can locoregional treatment of the primary tumor improve outcomes for women with stage IV breast cancer at diagnosis?

PURPOSE: To examine the effect of locoregional treatment (LRT) of the primary tumor on survival in patients with Stage IV breast cancer at diagnosis. METHODS AND MATERIALS: The study cohort comprised 733 women referred to the British Columbia Cancer Agency between 1996 and 2005 with newly diagnosed clinical or pathologic M1 breast cancer. Tumor and treatment characteristics, overall survival (OS), and locoregional progression-free survival were compared between patients treated with (n = 378) and without (n = 355) LRT of the primary disease. Multivariable analysis was performed with Cox regression modeling. RESULTS: The median follow-up time was 1.9 years. LRT consisted of surgery alone in 67% of patients, radiotherapy alone in 22%, and both in 11%. LRT was used more commonly in women with age <50 years, Eastern Cooperative Oncology Group (ECOG) performance status 0-1, Stage T1-2 tumors, N0-1 disease, limited M1 burden, and asymptomatic M1 disease (all p < 0.05). Systemic therapy was used in 92% of patients who underwent LRT and 85% of patients who did not. In patients treated with LRT compared with those without LRT, the 5-year OS rates were 21% vs. 14% (p < 0.001), and the rates of locoregional progression-free survival were 72% vs. 46% (p < 0.001). Among 378 patients treated with LRT, the rates of 5-year OS were higher in patients with age <50, ECOG performance status 0-1, estrogen receptor-positive disease, clear surgical margins, single subsite, bone-only metastasis, and one to four metastatic lesions (all p < 0.003). On multivariable analysis, LRT was associated with improved OS (hazard ratio, 0.78; 95% confidence interval, 0.64-0.94, p = 0.009). CONCLUSION: Locoregional treatment of the primary disease is associated with improved survival in some women with Stage IV breast cancer at diagnosis. Among those treated with LRT, the most favorable rates of survival were observed in subsets with young age, good performance status, estrogen receptor-positive disease, clear margins, and distant disease limited to one subsite, bone-only involvement, or fewer than five metastatic lesions.