How does radiotherapy cause hair loss?

Most people are aware that chemotherapy treatment for cancer causes hair loss, but the side effects of other cancer treatments such as radiotherapy are not well known or often discussed.

Although both treatments are used to eradicate cancer cells, radiotherapy differs from chemotherapy in that it is generally a more localised treatment. Whereas chemotherapy floods the body with cancer-killing chemicals, radiotherapy focuses solely on the cancerous area. However, chemotherapy and radiotherapy are often used together in conjunction with other treatments to give the patient the best chance of defeating their illness.

Similarly to chemotherapy, one of the most noticeable side effects of radiotherapy is hair loss. However, patients undergoing radiotherapy may experience hair loss (medically known as epilation) some months after their treatment has finished. This differs to chemotherapy, where hair loss is often evident after just two courses of treatment.

In line with the way in which the treatment works, hair loss after radiotherapy is generally localised, occurring in hair bearing skin within the radiation field. Hair loss after cancer treatment is not usually permanent, but it does occur in some cases where radiotherapy doses are very strong.