Survivin is a member of the inhibitor of apoptosis (IAP) family, and is also 
involved in the regulation of cell division. Survivin is widely expressed in 
foetal tissues and in human cancers, but generally not in normal adult tissue. 
This study examined the expression of surviving protein in a series of 293 cases 
of invasive primary breast carcinoma. Survivin immunoreactivity was assessed 
using two different polyclonal antibodies, and evaluated semiquantitatively 
according to the percentage of cells demonstrating distinct nuclear and/or 
diffuse cytoplasmic staining. Overall, 60% of tumours were positive for 
survivin: 31% demonstrated nuclear staining only, 13% cytoplasmic only, and 16% 
of tumour cells demonstrated both nuclear and cytoplasmic staining. Statistical 
analysis revealed that survivin expression was independent of patient's age, 
tumour size, histological grade, nodal status, and oestrogen receptor status. In 
multivariate analysis, nuclear survivin expression was a significant independent 
prognostic indicator of favourable outcome both in relapse-free and overall 
survival (P<0.001 and P=0.01, respectively). In conclusion, our results show 
that survivin is frequently overexpressed in primary breast cancer. Nuclear 
expression is most common and is an independent prognostic indicator of good 
prognosis.