Bystander Effect
Phenomenon where cells that do not directly receive treatment are affected through signals from nearby treated cells, relevant in radiation and targeted therapies.
Full Definition
In cancer biology, the bystander effect describes the observation that therapeutic effects can extend beyond directly targeted cells to affect neighboring untreated cells. This occurs through various mechanisms including gap junction communication, secreted factors, inflammatory responses, or immune activation. In radiation therapy, the bystander effect can enhance tumor cell killing beyond the direct radiation dose distribution. In targeted therapies and immunotherapies, bystander effects may contribute to abscopal responses where distant untreated tumors respond to local treatment. Understanding these effects is important for optimizing treatment protocols and explaining clinical responses that exceed predicted direct effects.
In Context
- "The radiation-induced bystander effect contributed to tumor control beyond the planned target volume." — Radiation oncology report
- "Research into the bystander effect mechanisms may inform combination therapy strategies." — Preclinical study