Long-term disease free survival (DFS) in patients with small breast cancer: clinical relevance of traditional and new prognostic factors in a retrospective study

Long-term disease free survival (DFS) in patients wth small breast cancer: clinical relevance of traditional and new prognostic factors in a retrospective study Type: Abstract Category: Breast Cancer, early stage Authors: A. Emiliani, L. Filomeno, A. Iannace, T. Losanno, G. Manna, E. Franzese, F.S. Di Lisa, P. Seminara; Rome/IT Aim The incidence rate of small-size (T1) early-stage breast cancer (EBC) has increased. The risk of relapse is low, but there is a growing interest in identifying traditional and new prognostic factors to optimize therapeutic management. Patients with T1 EBC, especially if node-negative (N0), are excluded from tumor gene expression profiling due to the cost of this procedure. Immunohistochemistry (IHC)-based classification of breast cancer subtypes with confirmed prognostic and therapeutic implication is therefore recommended. Methods We reviewed the records of 511 patients diagnosed with T1 EBC referred to our oncology unit for adjuvant therapy. This retrospective study evaluated the different long-term clinical outcomes over 15 years and correlated with traditional (T, N, ER and PgR, Ki-67, HER) and surrogate molecular subtype classification of the tumors using IHC prognostic factors. Results Patient characteristics were: median age 58.5 years (range 27-86). Tumor stage: T1a 74 (14.5%), T1b 120 (23.5%), T1c 317 (62.0%). Node status: N0 327 (64.0%), N1 184 (36.0%). Tumor grade: G1 144 (28.2%), G2 216 (42.3%), G3 151(29.5%). Ki-67 index: 20% 184 (36.0%). HER overexpression: absent 378 (73.9%), present 80 (15.6%). IHC molecular subtype was: Luminal A 199 (38.9%), Luminal B HER-negative 70 (13.7%), Luminal B HER-positive 65 (12.7%), HER overexpression 14 (2.7%), Basal-like 41 (8.0%). In the overall population, the significant prognostic factors at 5 years were N0 vs. N1 (p= 0.05), PgR 20% (p= 0.03), Ki-67 index 20% (p= 0.04) and Luminal A vs. Luminal B HER-negative (p= 0.05). At the 15-years follow-up, only Ki67 index confirmed its prognostic value (p= 0.04). In the N0 subgroup of patients DFS curves were significantly different for Ki-67 index 20% both at 5years (p= 0.01) and at 15 years (p= 0.03). Conclusion The DFS curves of T1 EBC patients at 5 years underline the prognostic relevance of the cut-off of 20%, both for PgR expression and Ki-67 index as well as IHC-based molecular subtypes Luminal A vs. Luminal B HER-negative. With regard to long-term outcome, only Ki67-index seems to be useful for identifying different prognostic tumor subgroups. These results were particularly important for improve current management of N0 EBC patients with prognostic risk factors