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Medline ® Abstract for Reference 63

of 'Dosing of anticancer agents in adults'

Relation between chemotherapy dose, oestrogen receptor expression, and body-mass index.
Colleoni M, Li S, Gelber RD, Price KN, Coates AS, Castiglione-Gertsch M, Goldhirsch A, International Breast Cancer Study Group
Lancet. 2005;366(9491):1108.
Clinicians often reduce chemotherapy doses when treating obese patients because of concerns about overdosing. We assessed dose-response according to body-mass index (BMI) and oestrogen receptor (ER) expression of the primary tumour in premenopausal patients with node-positive breast cancer treated with classical CMF (cyclophosphamide, methotrexate, and 5-fluorouracil). Obese patients were significantly more likely to receive a lower chemotherapy dose (<85% of expected dose) for the first course than were those with normal or intermediate BMI (39%vs 16%, p<0.0001). For obese patients and for the total population, reducing the dose of chemotherapy was associated with a significantly worse outcome for the ER-negative cohort (total population hazards ratio 85%vs<85% 0.68 [95% CI 0.54-0.86]for disease free survival; 0.72 [0.56-0.94]for overall survival) but not for the ER-positive cohort (1.16 [0.97-1.40]for disease-free survival; 1.16 [0.94-1.44]for overall survival) [interaction p values=0.0001 for disease-free survival and 0.0019 for overall survival]. Our findings suggest that for women with ER-absent or ER-low tumours, reduction in chemotherapy dose should be avoided.
European Institute of Oncology, Milan, Italy. marco.colleoni@ieo.it