Chemotherapy Doses for Obese Patients With Cancer

April 2, 2012

To help doctors give their patients the best possible care, the American Society of Clinical Oncology (ASCO) developed evidence-based recommendations on giving doses of chemotherapy that are based on a patient's actual weight. This guide for patients is based on ASCO recommendations and is intended for people who are obese.

Key Messages

  • Research on patients with cancer who are obese (extremely overweight) shows that they are more likely to die from cancer than those who are not obese, which may be partially due to how chemotherapy doses are determined.
  • Giving chemotherapy based on actual weight for patients who are obese often increases the dose, which makes treatment more effective without causing additional side effects.

Chemotherapy is a type of treatment commonly used for many types of cancer. It is the use of drugs to kill cancer cells, usually by stopping the cancer cells' ability to grow and divide. Systemic chemotherapy is often delivered through the bloodstream (called intravenously or IV) to reach cancer cells throughout the body. Some chemotherapy is given orally (by mouth) as a pill. A patient may receive one drug at a time or combinations of different drugs at the same time.

Chemotherapy doses are often based on ideal body weight, which is an estimate of a patient's body surface area (the size of the outside of the patient's body), rather than the patient's actual body weight and body surface area. Because of this approach, patients who are obese (determined by using a body mass index or BMI calculator) may be getting less chemotherapy for their actual weight and height than patients who are not obese. This is often because of concerns that higher doses of chemotherapy may cause more side effects. Studies estimate that up to 40% of patients who are obese do not receive doses based on actual body weight, which may affect their survival and risk of the disease worsening. Furthermore, studies show that higher doses do not cause more severe side effects.

Research has shown that patients with cancer who are obese are more likely to die from the disease than those who are not obese. Although the suspected causes of this difference in prognosis (chance of recovery) are complex, doses of chemotherapy that are not based on a patient's actual weight may contribute.

Recommendations for Giving Chemotherapy to Obese Patients

ASCO recommends that patients with cancer who are obese should receive chemotherapy doses based on their actual weight when the goal of treatment is to cure the cancer. However, because of possible side effects from specific drugs, ASCO recommends considering fixed (not based on weight) doses of a few drugs, such as carboplatin (Paraplat, Paraplatin) and bleomycin (Blenoxane). Also, no more than 2 milligrams (mg) of vinicristine (Oncovin) is recommended when used in the chemotherapy regimen called CHOP (cyclophosphamide [Clafen, Cytoxan, Neosar], doxorubicin [Adriamycin], vincristine, prednisone [multiple brand names]) or the regimen called CVP (cyclophosphamide, vincristine, prednisone).

What This Means for Patients

If you are obese, receiving chemotherapy based on your actual weight means that you'll receive more chemotherapy than if the dose is based on an ideal weight or a limited estimate. A higher dose based on your weight may help the chemotherapy work better to treat the cancer, and the research shows that receiving such a dose does not necessarily increase the side effects from treatment. Whatever dose you receive, your doctor will monitor your side effects closely. It's important to talk with your health care team about the specific type of chemotherapy recommended for you, how much of each drug you will receive, and how and when it will be given.

Questions to Ask the Doctor

Consider asking the following questions of your doctor:

  • What type of cancer do I have?
  • What is the stage? What does this mean?
  • What are my treatment options?
  • What treatment plan do you recommend? Why?
  • Will chemotherapy be a part of this plan?
  • If so, what are the goals of chemotherapy, and how do you determine the dose that is best for me?
  • Have you given me a dose based on my actual weight or a standard dose?
  • What are the side effects of treatment, and how can they be managed?
  • Will you monitor my side effects and decrease my dose if I have side effects?
  • Will you return to the original dose after my side effects go away?
  • If I'm worried about managing the costs related to my cancer care, who can help me with these concerns?
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