How to represent a big border matrix in latex?

I have tried a little, but getting confused how to represent the big curly braces on the top of the matrix? The MWE is as follows.

\documentclass{article}
$ETC = \begin{blockarray}{ccccc} & T_{11} & T_{12} & \cdots & T_{1_{|T1|}} \\ \begin{block}{@{}ccccc} C_{1} & ETC_{11,1} & ETC_{12,1} & \cdots & ETC_{1|T_{1}|,1} \\ C_{2} & ETC_{11,2} & ETC_{12,2} & \cdots & ETC_{1|T_{1}|,2} \\ \vdots & \vdots & \vdots & \vdots & \vdots \\ C_{n} & ETC_{11,m} & ETC_{12,m} & \cdots & ETC_{1|T_{1}|,m} \\ \end{block} \end{blockarray}$