Evaluation of Radiotherapy after Complete Response to Neoadjuvant Chemotherapy in HER-2 Positive Breast Cancer Patients

Lead Investigator: Youssef Zeidan, American University of Beirut Medical Center
Title of Proposal Research: Evaluation of Radiotherapy after Complete Response to Neoadjuvant Chemotherapy in HER-2 Positive Breast Cancer Patients
Vivli Data Request: 7583, 5932
Funding Source: None
Potential Conflicts of Interest: None

Summary of the Proposed Research:

Although treatment modalities of breast cancer are continuously evolving, evidence for the best treatment combination is still lacking in specific sets of patients. Administration of radiotherapy for HER-2 positive breast cancer patients that have received neoadjuvant targeted therapy/chemotherapy and achieved complete pathological response remains controversial in some clinical scenarios. This creates a clinical dilemma that has to balance the toxicities of radiation against its ability to eradicate probable occult malignant cells that can increase the risk of locoregional recurrence and decrease overall survival rates.

Statistical Analysis Plan:

Statistical strategy will be performed by the Clinical Research Institute at the American university of Beirut Medical Center (http://acc.aub.edu.lb/services/cri/)
Univariate analyses will be conducted to describe the cohort. Categorical variables will be presented as frequencies and percent, and continuous variables as means and standard deviations (SD).
Bivariate analyses will be used to compare characteristics as well as outcomes in frequencies and percent between exposed radiotherapy (+) and unexposed radiotherapy (-) groups, using the independent t-test (continuous variables) or the chi-square test (categorical variables).
Multivariate regression analyses will be used to evaluate the association between radiation and LRR while adjusting for potentially confounding variables. Moreover, results will be presented as odds ratios (OR) with their associated 95% confidence intervals (95% CI). Factors considered for inclusion in the multivariate analyses will depend on the statistical significance of the bivariate analyses, as well as the clinical significance of different characteristics.

Moreover, Kaplan Meier curves will be constructed to describe the time to recurrence in both radiation groups. Furthermore, to adjust for the confounding variables, while considering time to recurrence as an outcome, Cox proportional hazards regression modeling will be used to estimate the Hazard Ratios (HR) with 95% CI.
Statistical significance will be set at an alpha of 5% for a two-sided p-value. Analyses will be conducted using STATA.

Requested Studies:

A Randomised, Multicentre, Multinational Phase II Study to Evaluate Pertuzumab in Combination With Trastuzumab, Given Either Concomitantly or Sequentially With Standard Anthracycline-based Chemotherapy or Concomitantly With a Non-anthracycline-based Chemotherapy Regimen, as Neoadjuvant Therapy for Patients With Locally Advanced, Inflammatory or Early Stage HER2-positive Breast Cancer
Sponsor: Roche
Study ID: NCT00976989
Sponsor ID: BO22280

A Randomized, Open Label Study to Compare the Complete Pathological Response Rate Achieved With 4 Combinations of Herceptin, Docetaxel and Pertuzumab in Patients With Locally Advanced, Inflammatory or Early Stage HER2 Positive Breast Cancer
Sponsor: Roche
Study ID: NCT00545688
Sponsor ID: WO20697

Public Disclosures:

Saifi O, Bachir B, Panoff J, Poortmans P, Zeidan YH. Post-mastectomy Radiation Therapy in HER-2 Positive Breast Cancer after Primary Systemic Therapy: Pooled Analysis of TRYPHAENA and NeoSphere Trials. Radiother Oncol. 2023 Apr 6:109668. doi: 10.1016/j.radonc.2023.109668