Alopecia Health Article

Description

Alopecia, also called hair loss, baldness, and epilation, is a common side effect of chemotherapy and radiation therapy. Most patients undergoing chemotherapy, especially those who are being treated with more than one drug, will suffer from hair loss. Radiation therapy causes hair loss only in the area of skin being treated.

Although most often associated with head hair, alopecia can occur on any part of the body. Cancer treatments can also cause hair on the face (including the eyelashes and eyebrows), genitals, underarms, and body to fall out.

Alopecia usually occurs between two and three weeks after the first treatment. Most often, hair loss is gradual and occurs over a three-to-four week period. However, the chemotherapy drug paclitaxel can cause all the hair of the body to fall out within a 24-hour period. Loss of head hair usually begins on the top (crown) and sides of the head, presumably due to friction caused by pillows, bed linens, and hats.

Alopecia caused by chemotherapy is usually temporary. Hair loss caused by radiation therapy may be permanent. Hair regrows in about three to five months. Regrown hair may be a different color or type than before treatment.

Although alopecia is a harmless, painless condition, it can significantly affect body image, self esteem, and sexuality. As a result, alopecia may cause the patient to limit social activities. Hair loss can also cause depression.

Causes

To understand the cause of alopecia, it is helpful to understand how hair grows. Hair grows out of microscopic depressions in the skin called hair follicles. Normally, there are about 100, 000 hairs on a person's head (scalp). Each hair is in one of three different growth stages. Eighty-eight percent of the hair on the head is in the growing (anagen) stage, which lasts for two to five years. Some of the hairs are no longer growing and are in a resting (telogen) stage. The telogen stage lasts for three to five months. The transitional (catagen) stage lies in between the growing and resting stages. At the end of the telogen stage, the hair falls out. Usually about 100 hairs fall out each day. Alopecia becomes noticeable only after about half of the hairs have fallen out.

Chemotherapy-induced alopecia

Chemotherapy drugs kill the rapidly growing cancer cells. However, certain normal cells of the body are rapidly growing and they, too, are affected by the chemotherapy drugs. Rapidly growing cells are found in the base of the hair (hair bulb), as well as other parts of the body. When the drug kills the cells of the hair bulb, the hair falls out. Alternatively, the drug affects the hair bulb, causing the hair to narrow. This weakened hair is prone to breakage during normal brushing or shampooing.

Although many chemotherapy drugs can cause alopecia, certain ones are highly prone to causing hair loss. In addition, the way in which the drug is administered, the dose, and the treatment schedule can all influence the ability of a drug to cause alopecia. For instance, the fast administration of large doses of drug (bolus-dosing) is more toxic to the hair bulb than administering lower doses more slowly. Chemotherapy drugs with a very high potential to cause alopecia include:

• cyclophosphamide
• daunorubicin
• doxorubicin (at doses higher than 50 mg)
• etoposide
• ifosamide
• paclitaxel
• docetaxel

Radiation-induced alopecia

Like chemotherapy, radiation kills rapidly dividing cells. Hair loss occurs only at the site where radiation is applied. High doses of radiation (greater than 6, 000 cGy) usually causes permanent damage to hair follicles preventing hair from regrowing. If hair regrowth occurs, the hairs may be finer than before radiation therapy. However, hair usually regrows following low doses of radiation (less than 6, 000 cGy).