Journal of Clinical Oncology, Vol 16, 3731-3735, Copyright © 1998 by American Society of Clinical Oncology
Inflammatory breast cancer and body mass index
S Chang, AU Buzdar and SD Hursting
Department of Epidemiology, The University of Texas M.D. Anderson Cancer Center, Houston 77030-4095, USA. schang@mdacc.tmc.edu
PURPOSE: No studies have investigated the etiology of inflammatory breast
cancer (IBC), the most lethal form of breast cancer. Because high body mass
index (BMI) is associated with decreased risk of premenopausal breast
cancer but increased risk of postmenopausal breast cancer, we evaluated
whether high BMI was a risk factor for IBC. PATIENTS AND METHODS: In a
case-comparison study, we matched by ethnicity and registration date 68 IBC
patients treated at The University of Texas M.D. Anderson Cancer Center
from 1985 to 1996 with 143 patients with non-IBC and 134 patients with
cancer at sites other than the breast or reproductive tract (non-breast
cancer). The non- breast cancer group was used in lieu of a
population-based, healthy control group, which was not available. RESULTS:
IBC patients were younger at menarche and the time of their first live
birth than non-IBC and non-breast cancer patients. The proportion of
premenopausal IBC patients was higher than the proportion of premenopausal
women in the comparison groups, although differences were not significant.
There were no differences in height, but IBC patients were heavier (77.6
kg) than non-IBC (70.0 kg) and non-breast cancer patients (68.0 kg). After
adjusting for other factors, women in the highest BMI tertile (BMI >
26.65 kg/m2) relative to the lowest tertile (BMI < 22.27) had
significantly increased IBC risk (IBC v non-IBC, odds ratio [OR] = 2.45,
95% confidence interval [CI] = 1.05 to 5.73; IBC v non-breast cancer, OR =
4.52, 95% CI = 1.85 to 11.04). This association was not significantly
modified by menopausal status and was independent of age at menarche,
family history of breast cancer, gravidity, smoking status, and alcohol
use. CONCLUSION: Our investigation showed that high BMI was significantly
associated with an increased risk of IBC. This association did not vary by
menopausal status, although IBC patients were more likely to be
premenopausal. Confirming our findings and identifying other IBC risk
factors may provide directions for future research on the aggressive nature
of IBC.