"Heterogeneity of treatment effect on patients' long-term outcome according to pathological response type in neoadjuvant RCTs for breast cancer."

INTRODUCTION: To provide evidence explaining the poor association between pCR and patients' long-term outcome at trial-level in neoadjuvant RCTs for breast cancer (BC), we performed a systematic-review and meta-analysis of all RCTs testing neoadjuvant treatments for early-BC and reporting the hazard ratio of DFS (HRDFS) for the intervention versus control arm stratified by pathological response type (i.e., pCR yes versus no). METHODS: The objective was to explore differences of treatment effects on DFS across patients with and without pCR. We calculated the pooled HRDFS in the two strata of pathological response (i.e., pCR yes versus no) using a random-effects model, and assessed the difference between these two estimates using an interaction test. RESULTS: Ten RCTs and 8496 patients were included in the analysis. Patients obtaining pCR in the intervention-arm had a higher, although not statistically significant, risk of DFS-event as compared with patients obtaining pCR in the control-arm: the pooled HRDFS for the experimental versus control arm was 1.23 (95%CI, 0.91-1.65). On the opposite, the risk of DFS-event was higher for control as compared with the intervention-arm in the stratum of patients without pCR: the pooled HRDFS was 0.86 (95%CI, 0.78-0.95). Treatment effect on DFS was significantly different according to pathological response type (interaction test p: 0.014). CONCLUSION: We reported new evidence that contributes to explaining the poor surrogacy value of pCR at trial-level in neoadjuvant RCTs for early-BC.

Obesity and Breast Cancer: Interaction or Interference with the Response to Therapy?

Background: Aromatase inhibitors (AI) are widely used for treating hormone-sensitive breast cancer (BC). Obesity, however, due to aromatase-mediated androgen conversion into estradiol in the peripheral adipose tissue, might impair AI inhibitory capacity. We aimed at identifying a cut-off of body mass index (BMI) with significant prognostic impact, in a cohort of stage I-II BC patients on systemic adjuvant therapy with AI. Methods: we retrospectively evaluated routinely collected baseline parameters. The optimal BMI cut-off affecting disease-free survival (DFS) in AI-treated BC patients was identified through maximally selected rank statistics; non-linear association between BMI and DFS in the AI cohort was assessed by hazard-ratio-smoothed curve analysis using BMI as continuous variable. The impact of the BMI cut-off on survival outcomes was estimated through Kaplan−Meier plots, with log-rank test and hazard ratio estimation comparing patient subgroups. Results: A total of 319 BC patients under adjuvant endocrine therapy and/or adjuvant chemotherapy were included. Curve-fitting analysis showed that for a BMI cut-off >29 in AI-treated BC patients (n = 172), DFS was increasingly deteriorating and that the impact of BMI on 2-year DFS identified a cut-off specific only for the cohort of postmenopausal BC patients under adjuvant therapy with AI. Conclusion: in radically resected hormone-sensitive BC patients undergoing neoadjuvant or adjuvant chemotherapy and treated with AI, obesity represents a risk factor for recurrence, with a significantly reduced 2-year DFS.