Yes Smoking in any form or any thing over the years can cause cancer.
A new study by researchers at Fred Hutchinson Cancer Research Center has revealed that frequent and/or long-term marijuana use may significantly increase a man's risk of developing the most aggressive type of testicular cancer
http://.news.oneindia.in/2009/02/09/marijuana-use-linked-to-higher-testicular-cancer..
Marijuana doesn't cause cancer and in fact the THC in marijuana has been shown in studies to kill brain cancer cells. See link>>>http://www.youtube.com/watch?v=3OqSRfzqwWA&feature=related