Proliferative and apoptotic activity in lobular breast carcinoma.

Apoptotic and proliferative activity was studied in 25 invasive lobular breast carcinomas (ILC), and the relationship with conventional prognostic parameters [tumor size, nodal status, expression of estrogen (ER) and progesterone receptors (PR)] was investigated. Also 12 lobular carcinomata in situ (LCIS), 25 invasive ductal carcinomas (IDC) and 12 normal breast tissue controls were included. MIB-1 growth fraction (GF), mitotic index (MI) and the number of argyrophilic nucleolar organizer regions (AgNOR) served as proliferative parameters. Apoptotic index (AI) was determined after visualization of apoptoses by the TUNEL method. All parameters increased in the following order: control tissue - LCIS - ILC - IDC. Except for a negative correlation between GF and ER expression, no other significant relationship between any of the kinetical parameters and any prognostic parameter could be found in ILC. However, a significant inverse correlation between the GF:AI ratio and both ER and PR expression was registered. We conclude from our results a) that transition from non-invasive to invasive growth in lobular breast cancer is associated with an increased cellular turnover, and b) that proliferative activity is significantly lower in ILC than in IDC. The GF:AI ratio may possibly provide additional prognostic information in lobular breast cancer.