ER+ HER2- Invasive Breast Cancer: Tumor Remission following Viscum Album Extract/Influenza Vaccine Treatment - A Report of 2 Cases.

Introduction: Many patients with breast cancer use complementary and alternative medicine (CAM) including mistletoe preparations (Viscum album extracts, VAE). CAM alone has been associated with poor outcomes. Few, if any, confirmed breast cancer remissions have been reported with CAM treatment alone.

Case presentations: Case 1: 60-year-old female with a histologically confirmed local recurrence of hormone receptor positive (HR+) Her2/neu negative (HER2-) breast cancer 3 years after the initial diagnosis and treatment. The patient declined conventional therapies and was treated with intratumoral VAE plus intratumoral influenza vaccine (IV) and concurrent VAE-induced hyperthermia. Lumpectomy 5 months later confirmed a near pathological complete remission (near pCR). Follow-up at 3 years confirms durable remission. Case 2: 57-year-old female with histologically confirmed HR+, HER2- right sided breast cancer with 2-[18F]FDG-PET/computed tomography (CT) positive metastatic disease who declined conventional treatment. The patient was treated with 17 monthly cycles of VAE-induced hyperthermia, eight of which included intratumoral VAE, four of these eight including intratumoral IV. Almost 2 years after treatment start, a follow-up 2-[18F]FDG-PET/CT showed marked morphological and metabolic reduction of breast tumor on the right side, stable local lymph node metastases in the right axilla, complete remission of pulmonary metastases, the single bone metastasis, and the majority of hilomediastinal lymph node metastases but a new metabolic highly active left adrenal lesion.

Conclusions: Clinical studies of intratumoral VAE-influenza vaccine with concurrent VAE-induced hyperthermia in ER positive HER2/neu negative breast cancer are warranted.