Marion van Mackelenbergh

Surrogate End Points for Overall Survival in Neoadjuvant Randomized Clinical Trials for Early Breast Cancer

PURPOSE To assess trial-level surrogacy value for overall survival (OS) of the pathologic complete response (pCR) and invasive disease-free survival (iDFS) in randomized clinical trials (RCTs) for early breast cancer (BC). METHODS Individual patient data of neoadjuvant RCTs with available data on pCR, iDFS, and OS were included in the analysis. We used the coefficient of determination R 2 from weighted linear regression models to quantify the association between treatment effects on OS and on the surrogate end points. RESULTS Eleven RCTs, for a total of 15 treatment comparisons and 12,247 patients, were included in the analysis. There was a weak association between hazard ratios (HRs) for OS and odds ratio of pCR overall ( R 2 , 0.07; 95% CI, 0.00 to 0.48), as well as in all the subgroups explored. Overall, the R 2 for the association between HR OS and HR iDFS was 0.46 (95% CI, 0.08 to 0.71), which is just below the cutoff of 0.5 for moderate surrogacy. In the majority of subgroups explored, the R 2 ranged from 0.5 to <0.7, while in hormone receptor–/human epidermal growth factor receptor 2– subtype, histologic grade 1-2 tumors, and lobular tumors, surrogacy was strong (ie, R 2 ≥0.7). The surrogacy value of iDFS for OS was affected by follow-up (FUP) length: R 2 substantially increased up to 36 months of FUP, with little further improvement after 48 months of FUP. CONCLUSION iDFS with sufficient FUP is an acceptable surrogate end point to confidently anticipate final OS results of neoadjuvant RCTs for early BC. This recommendation holds true across many subgroups, with the notable exception of HR+ disease. There is definite need to reassess whether OS is the optimal end point for treatment efficacy measurement in HR+ early BC.

Calculating Future 10-Year Breast Cancer Risks in Risk-Adapted Surveillance: A Method Comparison and Application in Clinical Practice

Abstract The German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC) has successfully implemented risk-adapted breast cancer surveillance for women at high breast cancer risk in Germany. Women with a family history of breast and ovarian cancer but without pathogenic germline variants in recognized breast cancer risk genes are recommended annual breast imaging if their predicted 10-year breast cancer risk is 5% or higher, using the Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA) breast cancer risk model, as outlined in the current GC-HBOC guideline. However, women who initially do not meet this risk threshold may do so later, even if there is no new cancer in their family. To determine when this threshold is crossed, one could annually repeat BOADICEA calculations using an aging pedigree: the “prediction by aging pedigree” (AP) approach. Alternatively, we propose a simplified and more practical “'conditional probability” (CP) approach, which calculates future risks based on the initial BOADICEA assessment. Using data from 6,661 women registered with GC-HBOC, both methods were compared. Initially, 74% of women, ages 30 to 48 years, had a 10-year breast cancer risk below 5%, but 53% exceeded this threshold at an older age based on the AP approach. Among the women with an initial risk below the threshold, the CP approach revealed that 99% of women exceeded the 5% threshold at the same or an earlier age compared with the AP approach (88% of cases were within the same year or 1 year earlier). The CP approach has been implemented as a user-friendly web application. Prevention Relevance: The German Consortium for Hereditary Breast Cancer recommends annual breast imaging for women if their 10-year breast cancer risk is 5% or higher. Women who initially do not meet this risk threshold may do so later. We propose a simple method to determine future risks based on initial risk assessments.