How are biologic response modifiers best defined?

Biologic response modifiers are best defined as agents that alter immune responses to cancer. This category of treatment encompasses a variety of substances designed to enhance or restore the ability of the immune system to fight cancer. Unlike agents that directly attack cancer cells, biologic response modifiers work primarily by modifying the host's immune response, which can lead to improved recognition and destruction of cancer cells.

These agents can also help to stimulate the immune system more broadly, allowing it to act more effectively against tumors. This mechanism is especially important in the context of cancer treatment because many cancers can evade the immune response, so modifying this response can be a strategic approach to enhance the effectiveness of other cancer therapies and improve patient outcomes.

Other options, such as agents that only relieve symptoms or those that increase the rate of cell division, do not align with the primary function of biologic response modifiers, which is centered on immune system modulation rather than direct cancer cell destruction or symptom management.