American College Of Surgeons - Inspiring Quality: Highest Standards, Better Outcomes

Drug Therapies

Cancer cells grow and divide more quickly than normal cells. Chemotherapy, or "chemo," drugs target the division and function of fast-growing cells to kill them. Other treatments work in different ways.44

Drug therapies are divided into categories:

  • Chemotherapy drugs
  • Hormonal therapies
  • Antibody-based treatments
  • Targeted therapies


Chemotherapy may be given as a pill or through an IV line into the bloodstream. Chemotherapy is usually given in cycles of treatment followed by recovery time. The timing can be once a week or every second, third, or fourth week. You may receive one drug at a time or a combination.


Chemotherapy affects people in different ways. Chemotherapy drugs destroy both cancer and healthy cells. The destruction of normal cells may cause side effects. These side effects may be severe enough to stop treatment before the full course of treatment can be completed. The side effects will depend on:

  • The type of chemotherapy you are getting
  • The dose of chemotherapy you are getting
  • Your type of cancer
  • Your stage of cancer
  • How healthy you are before treatment

The most common side effects of chemotherapy include:

  • Fatigue (feeling tired)
  • Alopecia (hair loss)
  • Easy bruising and bleeding due to the killing of blood clotting cells
  • Infection due to the killing of white blood cells that fight infection
  • Anemia (low red blood cell counts)
  • Nausea and vomiting
  • Appetite changes
  • Constipation or diarrhea
  • Mouth and throat sores

To find out more about chemotherapy, the specific drugs, and ways to manage all of the side effects, go to the National Cancer Institute website.

Alopecia (hair loss) can occur on the scalp but also on the face, arms, legs, underarms, and pubic area. In most cases, hair will grow back after treatment is done. Many people use scarves, caps, hats, or wigs during hair loss. Your team will guide you so that you can prepare in advance. You may want to cut your hair short or be fitted for a cranial prosthesis (a wig). They are usually covered by insurance.

Woman with a head scarf

Keeping You Informed

Cool Cap Technology

Chemotherapy drugs kill all fast-growing cells, including hair cells. The damage to the hair follicle causes the hair to fall out (alopecia). Cooling the scalp leads to a decrease in the amount of chemotherapy drug in the scalp. This can reduce hair loss in 65 percent of breast cancer patients.45

Scalp cooling has been used since the late 1970s. Caps may be frozen to very low temperatures then placed on the head before, during, and after chemotherapy treatment. Other techniques use a machine that cools and circulates fluid through a cap.

Patient scalp cooling with Paxman System

Hormonal Therapy

Hormonal therapy fights hormone-receptor-positive breast cancers. These drugs reduce or block hormones like estrogen and progesterone that help these cancers grow. They help slow the tumor's growth and eventually kill it. Tamoxifen is one common hormone therapy drug that can be used in both premenopausal and postmenopausal women. Tamoxifen is an example of a selective estrogen receptor modulator (SERM).

Aromatase inhibitors decrease the amount of estrogen made by tissues other than the ovaries. They block the enzyme needed to make estrogen. They are effective only in postmenopausal women. Aromatase inhibitors include anastrozole (Arimidex®), letrozole (Femara®), and exemestane (Aromasin).

Antibody-Based Therapy

Antibodies are proteins produced by immune cells called B-lymphocytes (B-cells). Antibodies bind to foreign molecules (antigens) that enter the body. This tells the body that the object is foreign and marks it for destruction and removal. Some therapies help antibodies bind to cancer cells, marking them for destruction.

Targeted Therapies

Targeted therapies attack certain parts of cancer cells or other cells that help cancer cells grow. For breast cancer cells with certain genetic mutations, targeted medications may be a treatment option. Medications like trastuzumab (Herceptin) and pertuzumab (Perjeta®) may prevent tumor growth by stopping growth signals to receptors on the cell surface. Trastuzumab and pertuzumab may also be combined with chemotherapy.

Immunotherapy is a form of cancer treatment that uses the power of the body's own immune system to prevent, control, and eliminate cancer. A combination of atezolizumab (Tecentriq®) and nab-paclitaxel (Abraxane®) may be used for people with advanced triple-negative breast cancer. Triple-negative breast cancers tend to grow and spread quickly, and there are limited treatments available for this type of breast cancer.

To find out more about immunotherapy, visit the National Cancer Institute website.