Roles of adiposity, lifetime physical activity and serum adiponectin in occurrence of breast cancer among Malaysian women in Klang Valley

BACKGROUND: Lack of physical activities throughout life is related to obesity and is a risk factor of breast cancer, however, the associations of these factors with adiponectin in the occurrence of breast cancer have not been well investigated.

OBJECTIVE: This study investigated the relationship between adiposity, lifetime physical activities and serum adiponectin as breast cancer risk factors among Malaysian women in Klang Valley, Malaysia.

DESIGN: A case-control study was carried out among 70 newly diagnosed breast cancer patients and 138 controls aged 29 to 65 years old in Klang Valley.

SUBJECTS: The inclusion criteria for both groups were not having menstruation for premenopausal women, no evidence of pregnancy, not lactating and no chronic diseases such as hypertension and diabetes at the time of data collection. In addition, the cases must be pathologically newly diagnosed with breast cancer (stage I to III) and not on any therapy for cancer, with the exception of surgery. The controls were matched with cases for age +/- 5 years and menopausal status.

MEASUREMENTS: Subjects were interviewed to obtain information on socio-demography, health and reproductive history using a pretested questionnaire. Subjects were also asked on their engagement of physical activity since secondary school. Anthropometric parameters included height, weight, waist and hips were also measured. A total of 6 ml of fasting venous blood was drawn for analysis of serum adiponectin in duplicate using Linko Adiponectin ELISA Kit. Fasting blood glucose (FBG) and blood pressure were also measured.

RESULTS: Mean body mass index (BMI) among cases and controls were not significantly different (p> 0.05) at 26.1 -/+ 4.8 kg/m2 and 25.3 -/+ 4.5 kg/m2, respectively. FBG among cases (6.3 -/+ 1.8 mmol/L) was higher than controls (5.6 -/+ 1.1 mmol/L) (p<0.05). Waist hip ratio (WHR) of cases (0.85 -/+ 0.07) was also higher than controls (0.80 -/+ 0.06) (p<0.05). Abdominal obesity (WHR > 0.85) increased risk of breast cancer by three folds [Adjusted OR 3.3 (95%CI 1.8-6.2)] (p<0.05). Adiponectin level was inversely related to waist circumference (r=-0.510, p=0.000), BMI (r=-0.448, p=0.000) and FBG (r=-0.290, p=0.026). Adiponectin level in cases (11.9 -/+ 4.8 microg/ml) were lower than controls (15.2 -/+ 7.3 microg/ml) (p<0.05). A greater reduction of breast cancer risk was observed with the increasing level of serum adiponectin level according to percentiles (p<0.05). Subjects with mean serum adiponectin level at the highest quintile (> 75th)( >or= 16.7 microg/ml) had 80% reduced risk of breast cancer [Adjusted OR 0.2 (0.0-0.6)](p<0.05). A higher percentage of cases (47%) had not engaged in any physical activity throughout life as compared to controls (19%)[Adjusted OR 3.7 (1.7-7.7)](p<0.001).

CONCLUSIONS: Abdominal obesity and physical inactivity throughout life were associated with low serum adiponectin and breast cancer risk among subjects. Thus, it is essential for Malaysian women to be physically active and achieve a healthy waistline in order to increase serum adiponectin level and reduce breast cancer risk.