What type of immunotherapy is administered to initiate an antitumor effect without creating immunologic memory?

The correct answer relates to passive immunotherapy, which is designed to provide immediate, temporary effects by introducing pre-formed antibodies or immune cells directly into the patient. This approach activates the immune system against tumors without requiring the body to mount a sustained immunologic memory response, distinguishing it from active immunotherapy that aims to stimulate the patient's own immune system to develop long-term immunity.

In passive immunotherapy, the focus is on delivering external immune components that help fight the tumor at that moment, rather than inducing a prolonged immune response. This makes it particularly useful in immediate therapeutic settings where rapid intervention is needed.

Active immunotherapy, in contrast, engages the immune system in a way that often leads to immunologic memory, allowing the body to recognize and combat the tumor in the future. Nonspecific immunotherapy employs methods that stimulate the immune system broadly, yet often with lasting effects. Specific immunotherapy, such as targeting specific antigens on tumor cells, also tends to create a kind of immunologic memory due to the adaptive immune response it triggers.

Thus, passive immunotherapy is specifically effective in initiating antitumor effects without establishing long-term immune memory.