1.   Also, the tumors do not become resistant to angiogenesis inhibitors, as they do with drugs that are designed to poison the tumors.

2.   By contrast, tumors often become resistant -- that is, the drugs become ineffective -- when conventional chemotherapy agents that had originally been effective are administered again.

3.   For reasons yet to be determined, brain tumors are becoming more common, especially in older people.

4.   The larger the tumor became, the more hesitant the surgeons he visited became.

5.   They have the most to lose if they do nothing and the tumor becomes too advanced to treat and kills them.

6.   Tumors become resistant to chemotherapy drugs, Kerbel said, because cancer cells constantly reshuffle their genetic information.