Remarkably, in this small study, 46% of DCIS cases displaying adjacent IDC, but none of the DCIS only cases, were found to have allelic gene loss of SYK. Thus, in this preliminary study of DCIS, there appears to be a strong association of SYK allelic loss in DCIS tissues with adjacent invasive breast cancer. Here, SYK is linked to ductal breast carcinoma in situ.