Abstract 3679
Background
Incidence of gestational breast cancer (GBC) (during pregnancy, lactation or first year postpartum) ranges from 6-15% of BC in the 20-44 subgroup age. GBC is associated with positive nodes, negative hormonal receptors (HR), triple negative and high grade tumors but little is known at molecular level. We explore specific genomic profiles and clinico-epidemiological features of GBC.
Methods
Expression of 105 genes was assessed in 50 evaluable tumors from 70 GBC Spanish patients using nCounter platform. The following signatures were assessed: 1) Intrinsic subtypes; 2) Proliferation (P) and Risk of Recurrence (ROR) scores; 3) Claudin-low and 4) Chemo-Endocrine Sensitivity Predictor (CESP). Genomic profile and clinico-epidemiological data were compared to equivalent nonGBC cohorts from GEICAM/9906 (n = 293) (NCT00129922), Málaga (n = 96) (Cancer Res, 2016 76; P3 07 15) and Alamo III project (n = 1473).
Results
Out of the 70 patients, 43% were diagnosed during pregnancy and 57% postpartum. The table reports patient and tumor characteristics:
| n (%) | GBC | Alamo III | 9906 | Málaga |
|---|---|---|---|---|
| Mean age at diagnosis | 35 | 37 | 37 | 37 |
| Negative HR | 30 (43) | 330 (24) | 33 (16) | 27 (28) |
| T2-T4 | 51 (76) | 787 (56) | 176 (60) | 84 (92) |
| Grade 3 | 38 (63) | 479 (40) | 121 (44) | 38 (47) |
| Ki67 (≥20%) | 33 (89) | 209 (61) | 46 (22) | 60 (64) |
| Family history of BC | 32 (47) | 296 (25) | - | - |
| Mean age at first partum | 31 | 26 | - | - |
Intrinsic subtypes in GBC were 44% Basal-like, 22% Her2-enriched, 20% Luminal B and 14% Luminal A; no Claudin-low tumors were identified. Basal-like phenotype was enriched (44% vs 14%, p
Conclusions
GBC differential biology is suggested by higher Basal-like and lower Luminal A rates, and absence of Claudin-low phenotype, correlating with worse survival and a more aggressive clinico-pathological profile confirmed by a higher ROR-P high rate and lower CESP score.
Legal entity responsible for the study
GEICAM Spanish Breast Cancer Group
Funding
Sociedad Española de Oncologia Medica (SEOM): Grant “SEOM Buckler”, Fundacion BBVA: Solidarity project: “BBVA Solidarity Territories“ Donations from two Associations of Breast Cancer Patients “Rosae” and “Santa Agueda”
Disclosure
A. Prat: Consulting Fees (advisory boards) Nanostring Technologies. All other authors have declared no conflicts of interest.