Odds are that you have been faced with a similar dilemma. I have a new patient, not yet 40 years old, who was recently diagnosed with bilateral locally advanced breast cancer. Staging scans did not reveal metastatic disease. I recommended systemic therapy with doxorubicin, cyclophosphamide, a taxane, and trastuzumab followed by endocrine therapy. Pretty straightforward, right?
Here’s the problem: she is 61 inches and weighs 300 pounds. That translates to a body surface area (BSA) of 2.42 and a body mass index (BMI) of 56.7.
How should I dose her chemotherapy, given her morbid obesity? I sought advice from many of my medical oncology colleagues, all of whom I respect greatly. There was a true lack of consensus. A few said to “cap” her BSA at 2.0 m2. Others said to use ideal body weight. One colleague suggested that I treat her at full dose but to divide the anthracycline dose over two days.
Appropriate dosing of obese patients is a problem that oncologists are increasingly facing. More than 60% of Americans are overweight, obese, or morbidly obese. Some studies have shown that obesity increases the risk of developing certain cancers. Therefore, it is imperative that oncologists know how to optimally treat obese patients with cancer.
In my view, ASCO’s new guideline about appropriate chemotherapy dosing for adults with cancer is one of the most clinically useful treatment guidelines I have ever read. This comprehensive document contains an exhaustive systematic review of the literature and makes clear specific recommendations for optimal treatment of our obese patients based on evidence. The panel recommends full weight-based chemotherapy dosing, particularly when the goal of treatment is cure. With several exceptions, the use of fixed-dose chemotherapy is rarely justified. The panel explicitly states that there are no randomized trials of full weight-based chemotherapy vs. nonfull weight-based chemotherapy but based their recommendations on large observational and retrospective studies. It’s a great guideline, and I’d urge every oncology provider to read it.
Phew…Now I know what to do with my patient!