Thanks for your guidance, the seek command worked like a charm. Here's what I ended up using:

open THIS_FILE, "+<$listOption" or die "ERROR: SearchFile: $!";
    while (<THIS_FILE>) {
        if (/^$genre\t\d$/) {
            seek(THIS_FILE, -2, 1) or die;
            print THIS_FILE $option;
            seek(THIS_FILE, 1, 1) or die;
        }
      }
close THIS_FILE;
[download]

Pretty close to what you updated to. It took me a while to realize I shouldn't be using the 8 char read.

Thanx
-Zach (SFSC)