_GET variable security with query_posts?

I am using a form to find all custom field values of a particular key. This form is submitted and I use _GET to pass the value in query_posts.

Are there any security concerns with doing this? In this case it’s a dropdown select value that is getting found, but if I’m using text input should I use strip_tags or something like that to sanitize the input?

Here is an example…

if (!empty($_GET["property_type"])) {
     $ty = $_GET["property_type"];
} else {
    $ty = "";
}

query_posts( array(
		'posts_per_page' => -1,
		'meta_query' => array(
			array(
		                    'key' => 'property_type',
		                    'value' => $ty,
		                    'compare' => 'LIKE'
		                ),
			),
));