Impact of Sulforaphane on Breast Cancer Progression and Radiation Therapy Outcomes: A Systematic Review.

Breast cancer is a debilitating chronic condition that affects millions and causes the death of hundreds of thousands of people annually worldwide. Sulforaphane (SFN) has the potential to prevent and enhance the management of breast cancer and alleviate its poor outcomes. As most of the available evidence on SFN's impact and safety in breast cancer management is from cell culture studies and animal models, there is a need to consolidate this evidence to determine whether there is a need to conduct empirical human studies. This systematic review summarizes and analyzes evidence of SFN's impact on breast cancer progression and radiation therapy outcomes in terms of efficacy and safety. A systematic literature search was performed on PubMed, Cumulated Index in Nursing and Allied Health Literature, ProQuest Central, and ScienceDirect databases to find sources of evidence. The selected sources were published between 2018 and 2024. The inclusion and exclusion criteria included studies published in the last eight years, availability in full-text, published in English, and covering concepts relevant to the topic. The selected sources were summarized through literature review tables and the evidence was synthesized to identify themes relevant to the impact of SFN in breast cancer progression and radiation therapy outcomes. In total, 20 sources of evidence, including three randomized controlled trials, five in vivo animal models, and 12 cell culture studies, were selected for review and analysis. The sources were broadly classified into two themes, namely, the role of SFN in breast cancer biology and the safety of SFN in radiation therapy. The evidence confirmed that SFN targets breast cancer biology by modulating reactive oxygen species and reducing the proliferation of tumors, inducing apoptosis, and inhibiting metastasis. SFN is an effective and safer treatment as it reduces damage to and protects normal cells, causes a synergistic effect rather than interacting with other breast cancer cells, and is effective in concentrations ranging from 5 µM to 200 µM. Cell culture studies and animal models have proven that SFN is highly effective in breast cancer prevention and treatment either as a single intervention or in combination with radiotherapy and chemotherapy.