Enter email to receive results:   Question 1 of 25 1. Oral cancer is often undiagnosed because:It is impossible to seeIt is usually painlessIt looks like periodontal diseaseIt feels the same as a carious lesionQuestion 1 of 25Question 2 of 25 2. The reason that phen-fen is no longer on the market is because it is known to cause:High blood ...