What AJCC staging prefix indicates a case treated with neoadjuvant therapy?

The prefix that indicates a case treated with neoadjuvant therapy is "y." This designation is used to denote that the staging of the cancer has occurred after the patient has received preoperative treatment, which can include chemotherapy, radiation therapy, or both, given prior to the main treatment, which is usually surgery.

This staging prefix is crucial because it helps differentiate between the clinical stage of the disease before treatment and the pathological stage after treatment and surgery. By using "y," it conveys important information about how the tumor responded to the neoadjuvant therapy, which can be significant for treatment planning and prognostication.

The prefixes "p" and "t," while they serve distinct purposes in the AJCC staging system, do not indicate neoadjuvant treatment. "p" denotes pathological staging which is determined after the surgical resection, and "t" usually refers to the clinical staging at diagnosis, evaluating the extent of the tumor before any treatment. Therefore, "y" is the appropriate choice to indicate that neoadjuvant therapy has been part of the treatment pathway.