The Use of Cytoxan (Cyclophosphamide) in Breast Cancer Treatment

Nurse cleaning out chemotherapy infusion port
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Cytoxan, also known by its generic name cyclophosphamide, is a common chemotherapy drug that is used in combination with other medications to treat diseases like breast cancer.

Uses for Breast Cancer Treatments

Cytoxan is typically used after surgery to reduce the risk of early-stage breast cancer returning, before surgery to shrink advanced-stage tumors or after surgery to treat advanced-stage tumors.

Cytoxan is often combined with one other drug, Adriamycin, in a chemotherapy infusion to treat breast cancer. This combination is called AC. Please note that at present, FAC and CAF are rarely used.

Another chemotherapy combination used for breast cancer is Taxotere and Cytoxan. There also is a very old but still commonly use mixture called CMF, which has Cytoxan, methotrexate and 5-fluorouracil.

How It Works

Cytoxan works on cancer cells by damaging their DNA and, as a result, they can't keep dividing and they die. This drug will also affect normal cells but will have less effect on those cells since they divide more slowly and are better able to fix DNA breaks than cancer cells. Some of your normal cells that may be affected include blood, mouth tissue, digestive tract and hair follicles.

How It's Administered

Cytoxan can be given either intravenously as a solution or by mouth in pill form. If you are using capsules, make sure you take them whole. They cannot be cut, crushed or chewed. Cytoxan can also be administered through an intravenous chemotherapy infusion.

While you're taking Cytoxan or receiving infusions, you will need to drink more fluids and urinate more often. This will help prevent kidney and bladder infections that can develop if you are not hydrated enough.

What to Do During Treatment

Cytoxan can harm an unborn baby, so if you are pregnant or may become pregnant you should talk to your doctor about alternatives. Your doctor may also recommend reliable contraception in order to prevent any issues. It's also recommended that you avoid alcohol or caffeine, as they can be very dehydrating for your body and can cause issues for you. Your doctor will also tell you to switch from aspirin to ibuprofen for any pain relief. Cytoxan significantly impacts your system, so it usually encouraged to avoid vaccinations while undergoing treatment. 


The risks of going through Cytoxan chemotherapy include allergic reactions, potential harm to the fetus if you become pregnant, possible infertility in the future and low blood counts leading to a greater danger of infections.

Other side effects include Neutropenia, where you experience a low white blood cell count and greater risk of infection, hair loss, nausea, vomiting, diarrhea, fatigue, irritation in the mouth, menstrual cycle interruptions and brittle nails.

If you have any of these symptoms, you should call your doctor right away:

  • Fever of 100.5°F or higher
  • Painful or bloody urine
  • Black and sticky stools or bloody stools
  • Unusual bruises or bleeding
  • Persistent cough or pneumonia
  • Allergic symptoms: shortness of breath, swelling of feet or ankles, rash, swollen throat

Other Uses

It is used to treat breast and ovarian cancers, as well as lymphoma, leukemias, multiple myeloma, mycosis fungoides, neuroblastoma, and retinoblastoma.

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Article Sources
  • U.S. Food and Drug Administration. "Cyclophosphamide Prescribing Information". 
  • National Cancer Institute. "Drug Information – Cyclophosphamide". 2007.
  • American Cancer Society. "Drug Guide. Cyclophosphamide", 2004.