The Danish Breast Cancer Cooperative Group's register containing data from about 75 000 patients undergoing surgery for primary invasive breast cancer from 1978-2006 has been examined for classical pathological variables. During that period the diagnostic approach of malignant breast tumours experienced a major shift from invasive surgical procedures to non invasive procedures with an increase of the proportion of both fine needle aspiration biopsy and core needle biopsy. According to variation in tumour size there has been a slight increase in tumours <10 mm and a significant decrease in tumours >50mm from 7 to 4%. The distribution of the histological subtypes of malignant breast tumours has been almost unchanged. We found however a significant increase in the number of high grade tumours. A large increase in the number of removed axillary lymph nodes from 1989-2001 is related to improved surgical procedure. The subsequent decline from 2002-2006 is the result of the introduction of the sentinel node technique. In the five-year period 2002-2006 following the introduction of sentinel node technique, the frequency of patients having at least one lymph node metastases (48.7%) was higher than in the preceding five-year period 1997-2001 (44.4%, p=0.0087).