['To assess the influence of tumour location on axillary lymph node involvement (ALNI) and prognosis in breast cancer by evaluating the significance of the sagittal/horizontal alignment.', 'We compared 57 patients with superficially located breast carcinomas up to 3.0 cm with patients having lesions in posterior planes of the breast. Both groups were matched according to age, time of diagnosis, tumour size, grade, hormonal receptor status and tumour site within the frontal plane. Histologic evidence of skin involvement, excluding tumours fulfilling the criteria for pT4b, was defined as inclusion criteria and reference plane for superficial tumour location.', 'Tumours situated in the superficial region of the breast, compared to those located in deeper planes, have an increased risk of ALNI (p=0.023), whereas no difference was observed with reference to disease-specific survival (p=0.203).'] Does breast cancer sagittal/horizontal plane location influence axillary lymph node involvement?