From the Mayo Clinic website. It is called adjuvant therapy. Chemo is a therapy used “when there is no evidence of cancer on MRIs and/or scans.”

“Adjuvant therapy is often used after primary treatments, such as surgery, to lessen the chance of your cancer coming back. Even if your surgery was successful at removing all visible cancer, microscopic bits of cancer sometimes remain and are undetectable with current methods.”

Adjuvant therapy: Treatment to keep cancer from returning
Understand your options before you decide whether adjuvant therapy is for you. Balance the side effects with the benefits of treatment when making your decision.

Your doctor says the surgery to take out your tumor was a success, but then refers you to another doctor to consider more treatment — called adjuvant therapy.

What is adjuvant therapy?

Which treatments are used as adjuvant therapies?

Types of cancer treatment that are used as adjuvant therapy include:

Chemotherapy. Chemotherapy uses drugs to kill cancer cells throughout the body.

Hormone therapy. For cancers sensitive to hormones, certain treatments can stop hormone production in your body or block the effect of hormones.

Radiation therapy. Radiation therapy uses high-powered energy beams, such as X-rays or protons, to kill cancer cells. It can be given internally or externally.

Immunotherapy. Immunotherapy works with your body's immune system to fight off any remaining cancer cells by stimulating your body's own defenses or supplementing them.

Targeted therapy. Targeted therapy is designed to alter specific abnormalities present within cancer cells. For example, a targeted therapy is available to block the action of a protein called human epidermal growth factor receptor 2 (HER2) in women with breast cancer.