Neoadjuvant therapy is a preparatory treatment for cancer, administered before the primary treatment, which is usually surgery. This approach is distinct from adjuvant therapy, which is given after the main treatment. The goal is to use medication or other treatments to influence the cancer before its surgical removal. This initial phase of treatment is tailored to the individual and the specifics of their cancer.
Purpose of Pre-Surgical Treatment
The primary objective of neoadjuvant therapy is to reduce the size of a tumor before surgery. This process, known as downstaging, can make a previously inoperable tumor surgically removable. Shrinking the tumor may also allow for a less extensive operation, which can help preserve organs and improve cosmetic outcomes.
This preoperative approach provides an opportunity to observe how a specific cancer responds to treatment. It acts as a real-time test of the tumor’s sensitivity to a particular drug regimen. This information is valuable for planning subsequent treatment phases, and it helps medical teams confirm if the chosen treatment is effective.
Another goal is the eradication of micrometastases. These are small clusters of cancer cells that have broken away from the primary tumor but are too small to be detected by imaging tests. Systemic treatments circulate throughout the body to target these microscopic cells, which helps reduce the risk of the cancer returning.
Common Neoadjuvant Approaches
- Chemotherapy: Uses cytotoxic drugs that circulate through the bloodstream to kill rapidly dividing cancer cells throughout the body. This systemic approach targets both the primary tumor and potential micrometastases.
- Radiation therapy: Employs high-energy beams to damage and destroy cancer cells in a specific, targeted area. As a localized treatment, it focuses directly on the tumor and its immediate vicinity.
- Immunotherapy: Activates the patient’s own immune system to fight cancer. These drugs help immune cells recognize and attack cancer cells more effectively and can be used alone or with other therapies.
- Targeted therapy: Involves drugs that attack specific molecules or genetic mutations present on cancer cells. This approach interferes with the pathways cancer cells use to grow and spread, making it more precise than traditional chemotherapy.
- Hormone therapy: Used for cancers fueled by hormones, such as certain breast and prostate cancers. This therapy works by blocking hormone production or preventing hormones from affecting cancer cells, which slows or stops tumor growth.
Cancers Commonly Treated
Neoadjuvant therapy is a standard approach for certain types of breast cancer, particularly HER2-positive or triple-negative types. Pre-surgical treatment can allow for a lumpectomy—where only the tumor and a small margin of tissue are removed—instead of a more extensive mastectomy. The tumor’s response also helps guide post-surgical treatment decisions.
In the management of rectal cancer, neoadjuvant therapy aims to increase the distance between the tumor and nearby sphincter muscles. This improves the chances of preserving the sphincter, which can help the patient avoid needing a permanent colostomy bag after surgery.
For individuals with locally advanced lung cancer, neoadjuvant treatment can make a large tumor operable. This improves the likelihood of a successful surgical outcome for patients who might not have been candidates for surgery initially.
Neoadjuvant therapy is also used in treating bladder cancer to facilitate its complete surgical removal. Because this cancer has a risk of spreading, systemic treatments like chemotherapy can address potential micrometastases and improve long-term outcomes.
Evaluating Treatment Response
The effectiveness of neoadjuvant therapy is monitored throughout the treatment. Physicians use imaging techniques such as CT scans, MRIs, and PET scans to track changes in the tumor. These scans allow the medical team to see if the tumor is shrinking and to assess its metabolic activity.
After neoadjuvant therapy and surgery are complete, the removed tissue is examined by a pathologist. This examination, known as assessing the pathological response, provides a definitive measure of the treatment’s success.
A primary outcome is the pathological complete response (pCR), which means no residual invasive cancer cells were found in the tissue removed during surgery. Achieving a pCR is associated with a better long-term prognosis for the patient.