web07:~[0]% perl
$_ = 'word 0 word';
my @a = grep {s/(?<=\d),(?=\d)//g || $_} split;
print join ':', @a, "\n";
^D
word:word:
web07:~[0]%
[download]

That '0' vanished because the grep-condition (s/...//g || $_) is false and grep is a filter.