Multigene prognostic and predictive tests in Luminal breast cancer patients: relation between Mammaprint® results and nodal status in a retrospectively monocentric analysis

Abstract

Background: Breast cancer prognosis and predictive biomarkers development would allow sparing some patients from chemotherapy or identifying patients for whom chemotherapy would be indicated. Mammaprint can discriminate patients with good or poor prognosis and could help us to decide for using chemotherapy, especially in intermediate risk patients with Luminal subtypes. Material and methods: We evaluated with MP 81 consecutive patients ( pts) with invasive operable Luminal A or Luminal B breast cancer (pT1-4pN1-3M0) diagnosed from 2008 to December 2009 at Ferrara University Hospital. Treatment decisions were based on clinical-pathological features, regardless of the MP results. Then we retrospectively evaluated the patients clinic-pathological characteristics, focusing especially on nodal status, and their progression free survival in relation to the MP results. Results: Forty-two pts (51.9%) were Luminal A (LA) (ER = 10%, PR = 20% and Mib1 < 20%) and 39 pts (48.1%) were Luminal B (LB) (ER = 10%, PR < 20% or Mib1 = 20%), MP indicated a good prognosis in 27 (64.3%) LA and 14 (35.9%) LB pts and poor prognosis in 15 (35.7%) LA and 25 (64.1%) LB pts. MP results were significantly correlated with proliferative activity (p = 0.002), histological grade (p = 0.002), but not significantly correlated with nodal involvement (p = 0.220) and tumor size (p = 0.426). Between Luminal A pts, 22 (52.4%) were pN0 (15 MP low and 7 MP high risk), 15 (35.7%) with 1 to 3 node metastases (7 MP low and 8 MP high risk) and 5 (11.9%) with more than 3 lymph node metastases (all MP low risk). Considering instead LB pts 15 (38.5%) were pN0 (7 MP low and 8 MP high risk), 15 (38.5%) with 1 to 3 node metastases (7 MP low and 8 MP high risk) and 9 (23.1%) with more tha 3 lymph node metastases (all MP high risk). At a median follow-up of 70.5 months, 6 pts experienced disease recurrence: 1 (2.4%) between 42 LA pts with MP high risk and pN1 stage and 5 (12.8%) between 39 LB pts, 1 with MP low and pN0, and 3 with MP high (1 pN0, 1 pN1 and 1 with more than 3 lymph node metastases). Conclusions: Accurate prediction of recurrence risk is of vital importancefor tailoring adjuvant chemotherapy for each breast cancer patient, but our data confirm the unclear utility of Mammaprint in our clinical practice in comparison to classical prognostic parameters.