sed and comma-delimited file

[SigmaX asdf]

Yo;

I have a series of comma-delimited text files with fourteen columns of
data and several hundred rows.  I want to use a short shell script to
strip them of the last 9 columns, leaving the same file but with just
five of its columns.  I can do it in C++, but that seems like
overkill.  How would I go about doing it with sed or a similar
utility?

SigmaX