To evaluate cMET and phospho-cMET (p-cMET) levels in breast cancer subtypes and its impact on survival outcomes.
We measured protein levels of cMET and p-cMET in 257 breast cancers using reverse phase protein array. Regression tree method and Martingale residual plots were applied to find best cutoff point for high and low levels. Kaplan-Meier survival curves were used to estimate relapse-free (RFS) and overall (OS) survival. Cox proportional hazards models were fit to determine associations of cMET/p-cMET with outcomes after adjustment for other characteristics.
Median age was 51years. There were 140 (54.5%) hormone receptor (HR)-positive, 53 (20.6%) HER2-positive and 64 (24.9%) triple-negative tumors. Using selected cutoffs, 181 (70.4%) and 123 (47.9%) cancers had high levels of cMET and p-cMET, respectively. There were no significant differences in mean expression of cMET (P<0.128) and p-cMET (P<0.088) by breast cancer subtype. Dichotomized cMET and p-cMET level was a significant prognostic factor for RFS (HR:2.44,95%CI:1.34-4.44,P=0.003 and HR:1.64,95%CI:1.04-2.60,P=0.033) and OS (HR:3.18,95%CI:1.43-7.11,P=0.003 and HR:1.92,95% CI:1.08-3.44,P=0.025). Within breast cancer subtypes, high cMET levels were associated with worse RFS (P=0.014) and OS (P=0.006) in HR-positive tumors, and high p-cMET levels were associated with worse RFS (P=0.019) and OS (P=0.014) in HER2-positive breast cancers. In multivariable analysis patients with high cMET had a significantly higher risk of recurrence (HR:2.06; 95%CI:1.08-3.94,P=0.028) and death (HR:2.81; 95%CI:1.19-6.64,P=0.019). High p-cMET level was associated with higher risk of recurrence (HR:1.79,95%CI 1.08-2.95.77,P=0.020).
High levels of cMET and p-cMET were seen in all breast cancer subtypes and correlated with poor prognosis.