Is obesity always a risk factor for all breast cancer patients? c-erbB2 expression is significantly lower in obese patients with early stage breast cancer

The purpose of this study was to evaluate the relationship between body mass index and lipid profiles with breast cancer prognosis together with the relationship of these parametres with known breast cancer prognostic indices including c-erbB2 expression.

Four hundred and thirty-three patients diagnosed with breast cancer at Ankara University, Faculty of Medicine, Department of Medical Oncology made up the study population. The primary endpoints were relapse and death. Body mass index at the time of diagnosis, lipid levels at the time of diagnosis, estrogen receptor status, progesterone receptor status, c-erbB2 expression, tumor grade, patient age, axillary lymph node involvement level, tumor stage, menopausal status and surgery details were taken into account.

The mean body mass indices were similar in the remission, relapse and mortality groups. Patients with body mass indices higher than 30 kg/m² had a lower incidence of c-erbB2 expression when compared to patients with body mass indices < 18.5 kg/m² (19 vs. 50 %, p = 0.009). Survival analysis revealed that patients with body mass indices < 18.5 kg/m² had significantly shorter disease free survivals when compared to patients with body mass indices between 25 and 29.9 kg/m². Mean serum lipid levels were similar in the remission, relapse and mortality groups. A trend toward relapse was shown in patients with total cholesterol > 240 mg/dl, but this was statistically insignificant. Survival analysis revealed that patients with triglyceride levels lower than 150 mg/dl had a statistically significant longer disease-free survival when compared to the other groups. Again a trend towards shorter overall survival was seen in patients with total cholesterol > 240 mg/dl, but this relationship was also statistically insignificant.

Most large previous studies reported adverse breast cancer outcome with obesity. However in our study, patients with lower body weight had a shorter disease-free survival. This could be explained by the low number of patients in this study, genetic profile of the patient population, possible weight changes after treatment and the inverse relationship between body mass index and c-erbB2 expression.