Do you have an apache config for this site? If so, please post it so we can get a better idea of how you have your site set up.
Here is one way to do it (with mod_proxy and mod_rewrite):
ProxyPass / http://tource.com:8080/cms/admin
ProxyPassReverse / http://tource.com:8080/cms/admin
Proxy setting in Tomcat $TOMCAT_HOME/conf/server.xml
<Connector port="8080" protocol="HTTP/1.1"
redirectPort="8443" proxyPort="80" />
Restart apache and visit cms.tource.com to see if its working for you.