The chemicals suspected to be responsible for cancer due cigarette smoking arise in the incomplete combustion process that creates the smoke. Since the same combustion conditions would occur in any type of cigarette, cigar or pipe, the answer would likely be yes. However, it does not seem likely that cannabis would be smoked at the daily rate common in cigarette smoking so the dose of PCA's would be accordingly lower. This will make conclusive clinical evidence harder and longer to gather. Any scientific data gathering will likely get clouded by the smoke and by people's strong vested interest in one conclusion or another so don't expect an answer anytime soon.