Adjuvant

Adjuvant is a term used in medicine with two related meanings. In oncology, adjuvant therapy refers to additional treatment given after the primary treatment to lower the risk of cancer recurrence. In vaccinology and immunology, an adjuvant is a substance that enhances the body's immune response to an antigen in a vaccine without having substantial activity itself.

Adjuvant therapy follows surgical resection or radiotherapy when microscopic disease may remain. It can include chemotherapy, radiotherapy, hormone therapy, or targeted therapies, chosen based on tumor type, stage, and risk of recurrence. The aim is to improve disease-free and overall survival. Adjuvant treatment is not generally curative for metastatic disease and carries risks of toxicity; decisions balance potential benefits with side effects.

Vaccine adjuvants boost immune responses by activating innate immune pathways and enhancing antigen presentation, enabling stronger or longer-lasting immunity or allowing reduced antigen doses. Aluminum salts are among the oldest adjuvants; newer formulations include oil-in-water emulsions and toll-like receptor agonists. Safety assessment is essential, as adjuvants can cause local reactions or systemic effects in some individuals.

In oncology, adjuvant therapies may be systemic, targeting cancer cells throughout the body, or local, such as radiotherapy to the surgical bed. In vaccines, adjuvants influence the quality of the immune response, including antibody and T cell responses.