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Pre-clinical data suggest metformin might enhance the effect of chemotherapy in breast cancer (BC). We conducted a Phase II randomized trial of chemotherapy plus metformin versus placebo in metastatic breast cancer (MBC). In this double blind phase II trial we randomly assigned non-diabetic MBC patients on 1st to 4th line chemotherapy to receive metformin 850 mg po bid or placebo bid. Primary outcome was progression-free survival (PFS); secondary outcomes included overall survival (OS), response rate (RR), toxicity and quality of life (QOL). With 40 subjects and a type-one error of 0.2 (one-sided), a PFS hazard ratio (HR) of 0.58 could be detected with 80% power. 40 patients were randomized (22 metformin, 18 placebo) with a mean age of 55 vs 57 years and ER/PR positive BC in 86.4% vs 83.3% off metformin vs placebo, respectively. Mean BMI was 27kg/m2 in both arms. The majority of patients were on 1st line chemotherapy. Grade 3–4 toxicity occurred in 31.8% (metformin) vs 58.8% (placebo). Best response: Partial response 18.2% metformin vs 25% placebo, stable disease 36.4% metformin vs 18.8% placebo, progressive disease 45.4% metformin vs 56.2% placebo. Mean PFS was 5.4 vs 6.3 months (metformin vs placebo), HR 1.2 (95% CI 0.63–2.31). Mean OS was 20.2 (metformin) vs 24.2 months (placebo), HR 1.68 (95% CI 0.79–3.55). In this population metformin showed no significant effect on RR, PFS or OS. These results do not support the use of metformin with chemotherapy in non-diabetic MBC patients. • The addition of metformin to standard chemotherapy in non-diabetic metastatic breast cancer patients showed no significant effect on response rate, PFS or OS, as compared to placebo. • Metformin was associated with increased grade I and II adverse events and decreased global quality of life. [ABSTRACT FROM AUTHOR]

Background Treatment of breast cancer in elderly women is limited by declining functional status and life expectancy. The impact of providing less aggressive treatment remains controversial. This study assessed the treatment patterns of elderly breast cancer patients. Methods Retrospective chart review of women ≥70 y with breast cancer treated between 2004 and 2011 at two large Canadian cancer centres. Tumour and treatment characteristics were collected across three subgroups: 70–74 y (n = 314), 75–79 y (n = 233), and ≥80 y (n = 219). Comparisons were made using Chi-squared test, Fisher-Freeman-Halton exact test, or ANOVA. Disease free (DFS) and overall (OS) survival were estimated by Kaplan–Meier analysis and compared by log-rank test. Results Women ≥80 y had larger tumours that were better differentiated, hormone receptor-positive, HER2-negative, and lymph node (LN)-positive relative to younger women (p < 0.05). Women ≥80 y more frequently underwent mastectomy than breast conserving surgery and lacked LN staging (p < 0.05). Chemotherapy was provided in few patients, especially ≥80 y. Radiation therapy was provided less often in women ≥80 y despite indications. Hormone therapy was more frequently provided in women ≥80 y. Women ≥80 y had a significantly lower DFS (17.5 m) relative to women 70–74 y (31 m, p = 0.02) and 75–79 y (35 m, p = 0.006). Women ≥80 y had the lowest median OS (53 m) relative to 70–74 y (79 m, p = 0.001) and 75–79 y (75 m, p = 0.003) women. Conclusions Women ≥80 y received less aggressive treatment than younger women and had less favourable DFS and OS. Until age-specific recommendations are available physicians must use clinical judgement and assess the tumour biology with the patient's comorbidties to make the best choice. [ABSTRACT FROM AUTHOR]