Chemotherapy denotes the treatment of brain tumors with medication that is either toxic to tumor cells or kills them through interaction with receptors that induce 'programmed cell death' or prevent cell division. Chemotherapy is provided to over three-quarters of patients with malignant brain tumors. Less commonly treated are low-grade but symptomatic tumors that can not be surgically removed prior to or following radiation therapy.
Chemotherapy is usually given in cycles. A period of drug administration is followed by a resting period after which the cycle starts over again. Typically, a chemotherapy cycle lasts 4 to 6 weeks.
The chemotherapy dose is calculated based on your height and body weight. If you are given chemotherapy by mouth you will likely have to take a combination of pills of different strength to make up for the correct dose.
Chemotherapy is not only toxic to tumor cells. Adverse reactions usually affect cells of the body that have a rapid turnover such as blood cells and cells of the gastrointestinal tract.
Possible adverse reactions include:
- Drop in red blood cells (anemia). You may feel fatigued and get short of breath with exercise that you would usually tolerate without any difficulty. A medication called erythropoietin may be prescribed to shorten the recovery from the drop in red blood cells.
- Drop in white blood cells. You may be more susceptible to infections. If you have a fever or cold-like symptoms that do not resolve after a couple of days please notify your doctor. Your doctor may prescribe a medication called filgastrim to increase your white blood cell count.
- Drop in blood platelets. You may notice that you get bruises more easily than usual, your gums bleed when you brush your teeth or that you have nosebleeds. Notify your doctor immediately.
- Hair loss. Most chemotherapy regimens for primary brain tumors do not make you lose your hair. You will lose hair though in the area of brain radiation.
- Nausea and vomiting. You will be given a medication prior to each chemotherapy application. This usually prevents nausea very effectively. Notify your doctor if you suffer from nausea that does not respond to the medication.
- Diarrhea. Some of the chemotherapy regimens for primary brain tumors cause diarrhea. You will be given medication to counteract this effect.
- Allergic reaction. As with any other kind of medication there is a potential risk of an allergic reaction. If you notice a skin rash, dizziness, swallowing or breathing problems while on chemotherapy notify your doctor immediately. Please do not just stop the treatment on your own without telling your doctor since you may have reacted to a different medication or food.
- Food intolerance. With some chemotherapy drugs you have to avoid certain types of food. You will be given a detailed list by your doctor if applicable.
- Interactions with other drugs. Please provide your doctor with a complete list of medication including vitamins, ‘alternative’ cancer treatments, and ‘over-the-counter’ medication. Do not start yourself on medication such as cold medicine since, in rare instances, serious interactions with chemotherapy drugs may exist.
- Hearing loss. This is a rare occurrence with chemotherapy for most primary brain tumors. Typically, your doctor will obtain a hearing test prior to chemotherapy with a drug that may have this side effect.
- Kidney or liver failure. These are rare side effects of chemotherapy for primary brain tumors. You may require blood draws at scheduled intervals to monitor your kidney and liver function.
- Teratogenicity. It is mandatory that you practice effective birth control while you are receiving chemotherapy. Do not try to conceive a child while on chemotherapy. Severe damage to the unborn child may occur.
- Sterility. Sterility after chemotherapy is rare but its occurrence is unpredictable. It is strongly recommended that men who need to undergo chemotherapy and plan to have children afterwards deposit a sperm specimen at a ‘sperm bank’. Information and appointment scheduling for this service at Yale School of Medicine, Department of Obstetrics & Gynecology is available at (203) 785-5525.
- Pulmonary Fibrosis. A cumulative side effect of some chemotherapeutic agents is stiffening' of the lungs. This only occurs after a certain cumulative dose which is only rarely reached in the treatment of primary brain tumors. Your doctor may order a special lung scan to determine if early damage is present.
- Peripheral neuropathy. Some chemotherapy drugs (such as vincristine) can cause nerve damage. Your dose may have to be reduced if you develop early signs of nerve damage (tingling or numbness in fingertips and toes). The so called autonomic nerves (the nerves that innervate blood vessels and the intestines) can be affected as well. You may experience belly pain or dizziness when you get up too fast.
- Other types of cancer. Secondary malignancies, frequently affecting blood cells, can occur in 5-10 % of patients treated with certain chemotherapy agents.
Please notify your doctor immediately if you experience any side effects that you relate to the chemotherapy. You may need scheduled blood draws during each chemotherapy cycle. Usually you can have blood drawn at a local laboratory. Ask the laboratory to fax a copy of the result report to your doctors' office. Call your doctor or our clinical coordinator no later than one day after the blood draw to discuss the results.
Tumor cells can grow resistant to chemotherapy. Your doctor will obtain MRI scans on a regular basis to monitor the efficacy of treatment. If the tumor starts growing back in spite of chemotherapy, the treatment will need to be changed to a drug with a different attack mechanism.