Impact of the obesity on lymph node status in operable breast cancer patients.

PURPOSE: Although many studies have shown association of obesity and tumor size, the association with the lymph node status is not clear. We examined the relationship of the lymph node status and obesity and other possible factors in early breast cancer patients. METHODS: In this retrospective cohort study, 1295 breast cancer patients who had axillary dissection were included. Patients were grouped according to their body mass index (BMI) values at the time of diagnosis. We analyzed the relationship between BMI and patient and tumor characteristics, especially lymph node status. RESULTS: The median patient age was 48 years (range 20- 84). Of the patients 69.6% had modified radical mastectomy and the remaining 30.4% had breast-conserving surgery and axillary dissection. Median BMI of the patients was 27.2 kg/m(2) and 33.1% (N-429) of them had normal BMI, 36% (N-471) were overweight and 30.5% (N=395) were obese at the time of the diagnosis. Of the patients, 44.2% had N0 disease, and 55.8% had lymph node metastasis. N1 disease had 28.3% (N=367), 13.8% (N=179) had N2 and 13.7% (N=177) had N3 disease. When patients were classified as normal (≤24.9 kg/m(2)) and obese (>24.9 kg/m(2)) group, the total number of lymph nodes removed was higher in the obese group and this difference was statistically significant (18.12±10.48 and 20.36±11.37, respectively, p= 0.001). There was strong correlation between the number of the dissected lymph nodes and BMI (r=0.11; p<0.001). However, there was no statistically significant correlation between the number of metastatic lymph nodes and BMI. The mean number of the dissected and involved lymph nodes was higher in the HER2 positive group compared to the negative ones (21 vs 19, p=0.008; 6 vs 3, p<0.001; respectively) CONCLUSION: The number of the dissected lymph nodes was slightly higher in obese patients but there was no correlation between metastatic lymph node number and BMI. The number of the dissected and involved lymph nodes was higher in the HER2 positive group.