BACKGROUND: Breast cancer is the most common female cancer in North America. Axillary lymph node dissection (ALND) is important for staging, prognosis, and adjuvant treatment decisions. The purpose of this study was to identify factors that affect the number of lymph nodes (LN) retrieved in ALND for breast cancer. METHODS: All patients who underwent ALND for breast cancer at Sunnybrook Health Sciences Centre and Women's College Hospital between July 1999 and June 2006 were included. The number of LN retrieved was identified from pathology reports. Univariate and multivariate analysis was undertaken to identify variables influencing this outcome. RESULTS: 1084 patients were identified with a mean number of LN of 14.5. In multivariate analyses, significant covariates included sentinel LN biopsy (P = 0.011), degree of extranodal extension (P = 0.005), tumor grade (P = 0.058), and age (P = 0.043). Thirteen percent of the variation in LN yield was accounted for by institutional, provider, patient, and tumor related factors, leaving 87% attributable to inherent biological or other differences between patients. CONCLUSION: The yield of ALND may be influenced by multiple factors, often not related to the surgery. In settings where >10 LNs are routinely retrieved at ALND, biological variation between patients should be recognized as major a contributor to the LN yield. Adjuvant treatment decisions based on this outcome should take this into consideration.
BACKGROUND:Breast cancer is the most common female cancer in North America. Axillary lymph node dissection (ALND) is important for staging, prognosis, and adjuvant treatment decisions. The purpose of this study was to identify factors that affect the number of lymph nodes (LN) retrieved in ALND for breast cancer. METHODS: All patients who underwent ALND for breast cancer at Sunnybrook Health Sciences Centre and Women's College Hospital between July 1999 and June 2006 were included. The number of LN retrieved was identified from pathology reports. Univariate and multivariate analysis was undertaken to identify variables influencing this outcome. RESULTS: 1084 patients were identified with a mean number of LN of 14.5. In multivariate analyses, significant covariates included sentinel LN biopsy (P = 0.011), degree of extranodal extension (P = 0.005), tumor grade (P = 0.058), and age (P = 0.043). Thirteen percent of the variation in LN yield was accounted for by institutional, provider, patient, and tumor related factors, leaving 87% attributable to inherent biological or other differences between patients. CONCLUSION: The yield of ALND may be influenced by multiple factors, often not related to the surgery. In settings where >10 LNs are routinely retrieved at ALND, biological variation between patients should be recognized as major a contributor to the LN yield. Adjuvant treatment decisions based on this outcome should take this into consideration.