IntroductionThis study aimed at evaluating the overall survival (OS) gain associated with human epidermal growth factor receptor 2 (HER2)-directed therapies in patients with metastatic breast cancer (mBC).MethodsA bibliographic search was conducted in PubMed and Cochrane databases. Only phase III randomized controlled trials (RCTs) including HER2-positive (HER2+) mBC patients were included in this review. OS was defined as time from randomization until the occurrence of death from any cause. Studies have been grouped according to the line of treatment, i.e., first-line or second-line or beyond.ResultsNineteen RCTs were eligible for inclusion, of which 12 assessed therapies targeting HER2+ mBC in the first-line setting. OS improved from 20.3 months in the first RCT (standard chemotherapy; Slamon et al. (N Engl J Med 344:783–92, 2001)) evaluating HER2-targeting therapies to 48 months in the study of Swain et al. (Lancet Oncol 14:461–71, 2013), with triple combination of pertuzumab, trastuzumab and docetaxel. Seven RCTs evaluated the OS of HER2-targeting therapies in the second-line setting and beyond. The OS in second-line setting improved from 15.3 months (capecitabine; Cameron et al. (Breast Cancer Res Treat 112:533–43, 2008)) to 30.7 months (trastuzumab emtansine; Verma et al. (N Engl J Med 367:1783–91, 2012)). In the third-line setting, the association of lapatinib and trastuzumab has demonstrated to improve OS to 4.5 months compared with lapatinib alone (14 months vs. 9.5 months; Blackwell et al. (J Clin Oncol 30:2585–92, 2012)).ConclusionsHER2-directed therapies had an undeniable beneficial impact on the OS of patients with HER2+ mBC. The triple combination of docetaxel, pertuzumab and trastuzumab is associated with a survival extent of more than 4.5 years, compared with a life expectancy of 1.5 years achieved 14 years ago.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-015-0648-2) contains supplementary material, which is available to authorized users.

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BackgroundThe number needed to treat (NNT) is an absolute effect measure that has been used to assess beneficial and harmful effects of medical interventions. Several methods can be used to calculate NNTs, and they should be applied depending on the different study characteristics, such as the design and type of variable used to measure outcomes. Whether or not the most recommended methods have been applied to calculate NNTs in studies published in the medical literature is yet to be determined. The aim of this study is to assess whether the methods used to calculate NNTs in studies published in medical journals are in line with basic methodological recommendations.MethodsThe top 25 high-impact factor journals in the “General and/or Internal Medicine” category were screened to identify studies assessing pharmacological interventions and reporting NNTs. Studies were categorized according to their design and the type of variables. NNTs were assessed for completeness (baseline risk, time horizon, and confidence intervals [CIs]). The methods used for calculating NNTs in selected studies were compared to basic methodological recommendations published in the literature. Data were analyzed using descriptive statistics.ResultsThe search returned 138 citations, of which 51 were selected. Most were meta-analyses (n = 23, 45.1%), followed by clinical trials (n = 17, 33.3%), cohort (n = 9, 17.6%), and case–control studies (n = 2, 3.9%). Binary variables were more common (n = 41, 80.4%) than time-to-event (n = 10, 19.6%) outcomes. Twenty-six studies (51.0%) reported only NNT to benefit (NNTB), 14 (27.5%) reported both NNTB and NNT to harm (NNTH), and 11 (21.6%) reported only NNTH. Baseline risk (n = 37, 72.5%), time horizon (n = 38, 74.5%), and CI (n = 32, 62.7%) for NNTs were not always reported. Basic methodological recommendations to calculate NNTs were not followed in 15 studies (29.4%). The proportion of studies applying non-recommended methods was particularly high for meta-analyses (n = 13, 56.5%).ConclusionsA considerable proportion of studies, particularly meta-analyses, applied methods that are not in line with basic methodological recommendations. Despite their usefulness in assisting clinical decisions, NNTs are uninterpretable if incompletely reported, and they may be misleading if calculating methods are inadequate to study designs and variables under evaluation. Further research is needed to confirm the present findings.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-017-0875-8) contains supplementary material, which is available to authorized users.