Background: Many studies have analyzed the metastatic patterns of breast carcinoma. However, very few studies have analyzed the differences in metastatic patterns of lobular versus ductal carcinoma.
Methods: By use of our tumor registry, the metastatic sites of all invasive lobular and invasive ductal breast carcinoma cases during an 18-year period (January 1973 to December 1990) were analyzed.
Results: There were 2605 cases of invasive lobular and invasive ductal breast carcinoma. Lobular carcinoma accounted for 359 (14%) and ductal carcinoma for 2246 (86%) of the cases. The percentage of patients with regional lymph node metastasis at diagnosis was not significantly different between the two groups. The rates of metastasis to all lymph nodes, liver, and central nervous system were not significantly different. However, the rates of metastasis to the gastrointestinal system (4.5% vs 0.2%), gynecologic organs (4.5% vs 0.8%), peritoneum-retroperitoneum (3.1% vs 0.6%), adrenal glands (0.6% vs 0%), bone-marrow (21.2% vs 14.4%), and lung-pleura (2.5% vs 10.2%) were significantly different (p < 0.05).
Conclusions: The metastatic patterns of lobular and ductal carcinoma of the breast are different, with gastrointestinal system, gynecologic organ, and peritoneum-retroperitoneum metastases markedly more prevalent in lobular carcinoma. Physicians should be aware of these different metastatic patterns of lobular and ductal carcinoma of the breast.