Does it still not work if you do the following:

my $param = $q->param('report_type');
print "param=" . $param . "<BR>";
if( grep { /$param/ } (qw/case_id hosp_alias sender receiver/) ) {
    print "we are getting the list<BR>";
} else {
    print "we are NOT getting the list<BR>";
}
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If it still doesn't work, then something is wrong somewhere else. If this does work, then perhaps the answer is tied to Fletch's response to the post just before yours, Re: Strange behaviour of m and $_ - in that (quoting Fletch) "Subroutine invoations don't interpolate in double quoted strings (of which m// is a special kind.)"

s**lil*;  $*=join'',sort split q**;  s;.*;grr; &&s+(.(.)).+$2$1+; $; =
qq-$_-;s,.*,ahc,;$,.=chop for split q,,,reverse;print for($,,$;,$*,$/)
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