Are medical oncologists biased in their treatment of the large woman with breast cancer ?

Purpose. Obesity and breast cancer are common conditions that often coexist . Concerns of relative overdosing of chemotherapy in the large cancer patie nt have led clinicians to apply empiric dose reductions, 'cap' the body sur face area (BSA) at 2 m(2), or use ideal rather than actual body weight to c alculate BSA. There are no data supporting or refuting these practices and their prevalence is unknown. We sought to determine the distribution of bod y size and prevalence of obesity in the breast cancer population of our can cer centre, and to determine clinician chemotherapy dosing practices in the era of modern adjuvant chemotherapy. Patients and methods. Women with invasive breast cancer receiving systemic therapy at our institution between 1980 and 1998 were identified and their recorded height and weight were used to calculate BSA and body mass index ( BMI). We reviewed the first cycle adjuvant chemotherapy dosing practices fr om 1990-1998. The ideal dose of chemotherapy was calculated based on calcul ated BSA, and then contrasted with the actual dose received at cycle one. D iscrepancies were recorded and categorized, using the largest single drug r eduction if more than one drug was reduced. Results. Mean BMI in the systemic therapy population was 26.4 +/- 5.3 kg/m( 2), 54% were overweight, 2% severely obese and 18% moderately so. Their mea n BSA was 1.7 +/- 0.2 m(2) and only 5% had a BSA greater than or equal to2 m(2). In the adjuvant chemotherapy subgroup, most patients received > 85% o f their ideal dose. The mean dose reduction was 5.3 +/- 11.3% versus 9.9 +/ - 11.3% in the BSA <2 and >2 m(2) groups, respectively (p = 0.02), and 4.3 +/- 8.2% versus 6.7 +/- 13.1% in the BMI < 25 and greater than or equal to 25 kg/m(2) groups, respectively (p = 0.008). While only 24% of chemotherapy dose reductions of greater than or equal to 15% were in the BSA greater th an or equal to2 m(2) group, 76% were in the BMI greater than or equal to 25 kg/m(2) group. Conclusions. Obesity is prevalent in this breast cancer population. BSA is not a sensitive index of large body size. We consistently detected more fre quent empiric dose reductions at cycle one of adjuvant chemotherapy, with r eductions of greater magnitude in the largest women (BSA greater than or eq ual to2 m(2)) and those who were overweight (BMI greater than or equal to 2 5 kg/m(2)).