In recent years, the concept of sentinel lymph node biopsy has seen a paradigm shift in axilla management. It is current practice to offer axillary dissection to breast cancer patients with tumours greater than 3 cm even if clinically and radiologically node negative. Our study assessed whether axillary lymph node involvement was associated with quadrant location in breast cancer patients after controlling for tumour size and grade.
This population based, retrospective study examined females in Queensland who underwent surgery for invasive ductal breast carcinoma between the years 2002-2012 (n=9152).
Data was obtained from the Queensland Oncology Repository (QOR), a state wide cancer patient database that links cancer diagnosis data with death data from the registry of births, death and marriages (RBDM) and treatment data from public and private hospitals.
Multivariate negative binomial regression was conducted to determine the effect of tumour size, quadrant and tumour grade on node positive disease status. Incidence Rate Ratios (IRRs) were obtained for each category within tumour size, quadrant and tumour grade when compared to the reference category selected for each variable.
Breast cancer tumours were most commonly located in the upper outer quadrant (UOQ) of the breast (52%), followed by the upper inner quadrant (UIQ) (20%).
When compared to tumours located in the UOQ, tumours in the lower-inner quadrant* (LIQ) and upper inner quadrant** (UIQ) were less likely to be node positive (*RR 0.84, p=0.002; ** RR 0.68, p<0.001) while tumours located in the lower outer quadrant (LOQ) were more likely to be node positive (HR 1.08, p= 0.040).
Consideration may be given to axillary clearance in patients with outer quadrant tumours of less than 30mm size who are clinically and radiologically node negative.