Cyclophosphamide attaches to and damages the DNA in cancer cells when they are in their resting phase (not dividing). After their DNA is damaged, the cells can’t keep dividing, and their growth slows or stops.
Cyclophosphamide may be used in combination chemotherapy treatments for most types of invasive breast cancer, including triple-negative breast cancer. It can also be used with targeted therapy, such as trastuzumab (Herceptin), in treating HER2-positive breast cancers.
Other times cyclophosphamide can be used are
- AC (Adriamycin and Cyclophosphamide)
- AC-T (AC followed by Taxol)
- TC (Taxotere and Cyclophosphamide)
- CAF (Cyclophosphamide, Adriamycin and Fluorouracil)
- TAC (Taxotere, Adriamycin and Cyclophosphamide)
- CMF (Cyclophosphamide, Methotrexate, and Fluorouracil)
Cyclophosphamide can be taken by mouth or by vein. It is usually given in several cycles, with a day (or days) of treatment followed by a period of “off” days. The exact schedule varies depending on the combination of medicines. Most breast cancer chemotherapy regimens are given every 2 or 3 weeks.
In some cases your doctor may recommend a dose-dense schedule, which means medicines are given with less time between treatments than in a standard chemotherapy treatment plan. For example, one common treatment is dose-dense doxorubicin (Adriamycin) and cyclophosphamide (Cytoxan) every 2 weeks for four cycles, followed by paclitaxel (Taxol) every 2 weeks for four cycles. An entire course of chemotherapy for breast cancer usually takes from 3 to 6 months.
Because cyclophosphamide affects normal cells as well as cancer cells, it can cause many different side effects including:
- Nausea and vomiting
- Loss of appetite
- Hair loss or thinning
- Mouth sores
- Weight loss
- Menstrual cycle changes
- Nail and skin changes
- Decrease of white blood cells, red blood cells and platelets
- Taste changes
- Bladder irritation
- Nasal congestion
While you are taking cyclophosphamide, drink lots of fluids to avoid kidney and bladder side effects. Ask your doctor how much and how often you should drink each day. Call your doctor if you see blood in your urine.
Cyclophosphamide can cause long-term damage to the bone marrow. This means it can slightly increase your risk of developing leukemia, a blood cancer, when given in high doses.