Curly braces using mtpro2[lite]: fix correct alignment

Question

I am trying to find a solution, but actually I have failed, to use curly bracket (using \ccases) for the system symbol of three equations (or more), as for this example. If I adding the & I have much space,

\documentclass{article}
\usepackage[lite]{mtpro2}
\usepackage{mathtools}
\begin{document}
\[\ccases{
x&=R\sin\theta\cos\varphi\\
y&=R\sin\theta\sin\varphi\\
z&=R\cos\theta}
\]
\end{document}

While if I remove the symbol & I lose the vertical alignment of the sign =:

\documentclass{article}
\usepackage[lite]{mtpro2}
\usepackage{mathtools}
\begin{document}
\[\ccases{
x=R\sin\theta\cos\varphi\\
y=R\sin\theta\sin\varphi\\
z=R\cos\theta}
\]
\end{document}

How can I have the correct vertical alignment with the three = symbols without have additional spaces?

ADDENDUM: Here there is an image which compares the classic brace with the elegant curvy brace:

First guide mtpro2 page 12 and second guide mtpro2-2008/1/23 and possible related:

1. Overwrite dcases* to work inside align (to use mtpro2 braces)
2. Overwrite matrix to work inside align (to use mtpro2 parentheses and braces)

Answer 1

Within the scope of \ccases{...}, the & symbol performs the same function as it does inside the cases environment of the amsmath package, i.e., it creates a certain amount of horizontal separation (as well as vertical alignment). However, that's not what you want here, is it?

To get the desired spacing around the = symbols, I recommend that you encase the three equations in an aligned environment, regardless of whether you use the \ccases macro or the cases environment.

\documentclass{article}
\usepackage[lite]{mtpro2}
\usepackage{amsmath}

\begin{document}
\[
\ccases{
  \begin{aligned}
    x &= R\sin\theta\cos\varphi\\
    y &= R\sin\theta\sin\varphi\\
    z &= R\cos\theta
  \end{aligned}
}
\quad\text{vs.}\qquad
\begin{cases}
  \begin{aligned}
    x &= R\sin\theta\cos\varphi\\
    y &= R\sin\theta\sin\varphi\\
    z &= R\cos\theta
  \end{aligned}
\end{cases}
\]
\end{document}