A new study has reported that whether breast cancer is classified as ductal or lobular is not directly linked to prognosis. Rather, the outcome depends on hormone receptor status, the number of positive lymph nodes, and tumor grade and size. The study was designed to examine whether histological subtyping of breast cancer as either ductal or lobular is related to disease outcome. Ductal breast cancer develops in the milk ducts of the breasts whereas lobular breast cancer forms in the cells that line the milk-producing glands. Treatment decisions in breast cancer typically depend on TNM (tumor-node-metastasis) classification. However, additional variables may have an impact on survival. The study was conducted by examining a database of 14,198 breast cancer patients.
Classification of invasive breast cancer as either ductal or lobular was not found in and of itself to be correlated with disease outcome. However, the data showed that lobular breast cancer was more likely to be estrogen receptor and progesterone receptor positive (ER+/PR+) and a lower probability of being HER2 overexpressing. Patients with lobular breast cancer also had a higher average age at the time of diagnosis compared to those with ductal breast cancer. Local recurrence rates were found to be lower among those with lobular breast cancer compared to those with ductal breast cancer (3.5% vs. 6.2%). ER, PR, lymph node status, tumor grade and tumor size predicted disease outcome with statistical significance, whereas histological subtype (ductal or lobular) was not significantly associated with prognosis.