Glossary — R

Radiation therapy uses focused beams of high-energy radiation — most often X-rays — to damage the DNA inside cancer cells so they can no longer divide and grow. It may be used alone or alongside surgery and chemotherapy, depending on the type and stage of cancer being treated.

A radiologist is a medical doctor who has completed specialized training in interpreting imaging studies — such as mammograms, MRIs, CT scans, and ultrasounds — to detect disease and guide treatment decisions. Radiologists typically work behind the scenes, analyzing images and communicating findings to your primary care physician or specialist.

Receptor-positive breast cancer means the cancer cells have surface proteins — receptors — that bind to hormones such as estrogen or progesterone and use them to fuel growth. This status is determined by pathology testing of a biopsy sample and is important because receptor-positive cancers can often be treated with hormone-blocking therapies.

Recurrence means that cancer has come back after it appeared to be gone or under control. It can return in the same location as the original tumor (local recurrence), in nearby tissue or lymph nodes (regional recurrence), or in a distant part of the body (distant recurrence or metastasis). Continued monitoring after treatment is designed specifically to detect recurrence early.

Relapsing-remitting MS (RRMS) is characterized by clearly defined attacks — called relapses or exacerbations — during which new or worsening neurological symptoms appear, followed by periods of partial or complete recovery (remission). It is the most common course of MS at the time of diagnosis, affecting roughly 85 percent of people newly diagnosed.

Remission means that the signs and symptoms of cancer have decreased significantly or cannot be detected by current tests and scans. A partial remission indicates a major reduction in the cancer, while a complete remission means no cancer can be found. Remission does not always mean the cancer is permanently gone — it means treatment has worked and close monitoring continues.

A risk factor is anything — a personal characteristic, a behavior, a family history, or an environmental exposure — that raises the statistical likelihood that a person will develop a specific disease. Having one or more risk factors does not mean you will definitely get a disease; it means your probability is higher compared to someone without those factors.