ILC is the second most common BC type after the invasive carcinoma of no special type (NST). It mostly presents as estrogen receptor (ER) and progesterone receptor (PR) positive, human epidermal growth receptor 2 (HER2) negative and with a low marker of proliferation (Ki67) which results in a luminal A subtype and E-cadherin loss. Additionally, it appears to have a metastatic pattern that differs from the NST. This registry study aims to show clinical and pathological parameters in patients with early and advanced ILC.
Clinical and pathological data of 683 patients diagnosed with ILC were retrospectively collected and descriptively analyzed. Of these, 206 patients (30.2%) subsequently developed a local recurrence and/or distant metastasis.
The majority of ILC patients presented with low Ki67, positive ER and PR, HER2-negativity and an intermediate grade tumor. E-cadherin loss was detected in 96.2% (n=427, 256 unknown). In summary, 0.4% of patients exhibited a pTis, 45.7% a pT1, 37.3% a pT2, 15.5% a pT3 and 1.1% a pT4 tumor (n=451, 26 unknown), while 68% of patients had pN0, 20.3% pN1, 7.3% pN2 and 4.3% pN3 status (n=438, 39 unknown). ILC tumors with a subsequent metastatic event initially showed similar data to non-metastatic tumors, although metastatic tumors have the highest rate in pT2 with 44.4% but 39.2% presented with pN0 in. Distant metastases were detected at the following sites: bones (43.7%; n=90), local recurrence (33.4%; n =69), peritoneum (12.6%; n=26), liver (11.2%; n=23), gynecological metastasis (10.7%; n=22) (multiple sites per person possible). Patients who progressed showed a slightly different profile, with a particular increase in cerebral lesions (24%, n=24).
This registry study summarizes histopathological data of ILC patients and shows a high rate of metastatic events despite initially good prognostic factors. The metastatic sites in this cohort resemble other studies and differ from NST in the frequency of visceral metastasis or metastasis inside the abdominal cavity (28.2%, n=58) in our cohort. This should be taken into consideration for planning surveillance for ILC patients in survivorship care.
AG Karsten-Speiser, Department of Gynecology with Breast Center, Charité - Universitätsmedizin Berlin.
Has not received any funding.
P. Jank: Financial Interests, Personal and Institutional, Stocks/Shares: Myriad Genetics Inc. M.M. Karsten: Financial Interests, Personal, Invited Speaker: Roche, Gilead, Sysmex. All other authors have declared no conflicts of interest.