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PurposeTo provide recommendations for appropriate cytotoxic chemotherapy dosing for obese adult patients with cancer.MethodsThe American Society of Clinical Oncology convened a Panel of experts in medical and gynecologic oncology, clinical pharmacology, pharmacokinetics and pharmacogenetics, and biostatistics and a patient representative. MEDLINE searches identified studies published in English between 1996 and 2010, and a systematic review of the literature was conducted. A majority of studies involved breast, ovarian, colon, and lung cancers. This guideline does not address dosing for novel targeted agents.ResultsPractice pattern studies demonstrate that up to 40% of obese patients receive limited chemotherapy doses that are not based on actual body weight. Concerns about toxicity or overdosing in obese patients with cancer, based on the use of actual body weight, are unfounded.RecommendationsThe Panel recommends that full weight–based cytotoxic chemotherapy doses be used to treat obese patients with cancer, particularly when the goal of treatment is cure. There is no evidence that short- or long-term toxicity is increased among obese patients receiving full weight–based doses. Most data indicate that myelosuppression is the same or less pronounced among the obese than the non-obese who are administered full weight–based doses. Clinicians should respond to all treatment-related toxicities in obese patients in the same ways they do for non-obese patients. The use of fixed-dose chemotherapy is rarely justified, but the Panel does recommend fixed dosing for a few select agents. The Panel recommends further research into the role of pharmacokinetics and pharmacogenetics to guide appropriate dosing of obese patients with cancer.

Thromboembolic disease has long been recognized as a complication of cancer. Recent reports have suggested that drugs used in the treatment of cancer, including chemotherapeutic agents and hormones, may contribute to this risk, but it has not been possible to separate the effect of these drugs from that of the cancer. We performed a randomized trial comparing 12 weeks of chemohormonal therapy (using cyclophosphamide, methotrexate, fluorouracil, vincristine, prednisone, doxorubicin, and tamoxifen) with 36 weeks of chemotherapy (using cyclophosphamide, methotrexate, fluorouracil, vincristine, and prednisone) in patients with Stage II breast cancer. Among 205 patients randomly assigned to treatment, there were 14 episodes of thrombosis (6.8 percent). These 14 episodes occurred during 979 patient-months of chemotherapy; by comparison, there were no events during 2413 patient-months without therapy. During the first 12 weeks of the study, five patients in the 12-week group and four patients in the 36-week group had thrombosis. During the subsequent 24 weeks, when only patients in the 36-week group were still receiving chemotherapy, there was no thrombosis in the 12-week group, but there were five additional events in the 36-week group (P = 0.03). These findings suggest that chemotherapy contributes to thrombosis in patients with breast cancer.