Abstract P6-03-06: Assessing occult brain metastasis with CT scan or MRI in HER2-positive breast cancer patients at initial diagnosis
Authors: Delbaldo C , Sarrade T , Brieau B , Billemont B , Denis J , Cojean-Zelek I , Bornier C , Vincens E 
Published: February 2018

Patients (pts) with HER2-positive breast cancer (BC) have a high risk of developing brain metastases (BM) that might be due to longer survival, low diffusion of Trastuzumab (T) in the CNS or an unknown incidence of occult BM at diagnosis. In a series of metastatic BC, occult metastasis was found in 15 % of the patients and Her2 over expression was an independent risk factor 1.In a series of early BC treated with T the cumulative incidence of BM at 12 and 24 months was 0.6 and 2 % respectively 2. Time to BM was 13.7 months in retrospective study 3 . Systematic cranial magnetic resonance imaging (MRI) in the staging of HER2-positive BC pts detected BM in 22 % of asymptomatic, metastatic pts versus 3.6 % in asymptomatic, non-metastatic pts 4. Early detection of BM decreases the cerebral death rate, but do not prolong survival in metastatic pts 4 . Therefore brain imaging is not recommended at diagnosis. However, retrospective trials assessing the incidence of BM in HER2-positive BC were mainly performed during follow up and not at the initial diagnosis.

Pts treated for HER2-positive locally BC with adjuvant sequential chemotherapy including anthracycline and taxane associated with T, classified according to classical prognosis factor as histological subtype, TNM, SBR and hormonal receptor (HR), were systematically assessed for occult BM at initial diagnosis with CT scan or MRI. Retrospectively analyzed for the occurrence of BM was performed. Disease free metastatic survival (DFMS) and overall survival (OS) was estimated by Kaplan Meier estimation.

Between March 2006 and July 2013 84 pts were included. The median follow up is 4.7 years. The characteristics pts were median age 57 years [30-86], ductal carcinoma 67 pts (93 %), lobular carcinoma 5 pts (7%), pT1 to 4 respectively 38 (48 %), 28 (36 %), 3 (4%), 9 pts (12%), pN 0 to 3 respectively 44 (54%), 27 (33%), 5 (6%), 5 pts (6%), SBR 1 to 3 respectively 1 (1%), 35 (43%), 43 pts (54%), RO positive 47 pts (59 %), RP positive 27 pts (63%). Thirty eight pts (45 %) had brain imaging at diagnosis or within 5 months of diagnosis. Only one pt with a pT4, pN2, ductal carcinoma, RO+, RP-, SBR 2 presented with BM (2.6 %) at initial diagnosis, with simultaneous lung, liver, bone and nodes metastasis. Four pts (4.8 %) presented BM during follow up, among those two symptomatic pts (2.4 %) as the only site of recurrence at 21 and 28 months. Median DFMS was 8.5 years and median OS was 16.7 years.

This is the first report of systemic imaging at initial diagnosis of HER2 positive locally BC pts. The results did not support initial brain imaging in this subset of pts. Only pts with symptoms seems to benefit from brain imaging. Further prospective study should be launched to confirm this observation.

Citation Format: Delbaldo C, Sarrade T, Brieau B, Billemont B, Denis J, Cojean-Zelek I, Bornier C, Vincens E. Assessing occult brain metastasis with CT scan or MRI in HER2-positive breast cancer patients at initial diagnosis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-03-06.