Tumour location and axillary lymph node involvement in breast cancer: a series of 3472 cases from Sweden

Aim. This study investigates the potential relation between breast cancer location and axillary lymph node involvement (ALNI). Methods. Out of all cases with unilateral first-time diagnosis of invasive breast cancer in Malmö, Sweden, between 1961 and 1991, 3472 underwent axillary dissection. The association between tumour location and ALNI was investigated using logistic regression analysis (adjusted for potential confounders) yielding odds ratios (OR), with a 95% confidence interval. All analyses were repeated in different birth-year cohorts. Results. Outer tumours (upper outer or lower outer quadrants), as compared to inner (upper inner and lower inner quadrants), were associated with a statistically significant risk of ALNI, OR: 1.31 (1.11–1.55). Central tumours were also associated with ALNI, OR: 2.61 (2.08–3.27). Among women born before 1909, corresponding OR:s for outer tumours was 1.61 (1.19–2.18), and for central tumours 3.50 (2.32–5.28). Conclusions. Outer and central breast tumours are associated with a high risk of axillary lymph node involvement.