1. "You poor thing, I feel so sorry for you." People with cancer need compassion, not pity. Pity implies hierarchy, while compassion puts you on the same level.

2. "What's your prognosis?" Prognosis is a medical term and it makes most people with cancer think about how long they might survive. Even if they're positive thinkers, they may not want to think about how long doctors indicate they're going to live.

3. "Let me know if there's anything I can do to help." This might seem like a helpful statement. But according to my research, that statement is one of the least helpful. When people have cancer, they may feel so overwhelmed that they can't focus on what they need. Offer something specific -- run an errand, give a foot rub, weed their garden.

4. "My aunt [or anyone] died of breast cancer." Tell positive stories, never scary stories, about other people who have had cancer. More than anything, people with cancer need hope, and horror stories dash hope.

5. "At least they caught it early [or "at least" anything]." Your friend needs to know you're acknowledging his pain and taking it seriously. If you say, "At least you don't have to go through chemo..." or something similar, you minimize what he's going through. He may discover what's good about his situation himself, but doesn't want to hear it from you.

NEXT: What you should say