Health: Surviving Cancer

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The better that researchers know a cancer, the better their chances of defeating it. Those odds also improve if doctors have more than one way to fight it. As they fill in the details--at the molecular level--of the world in which tumors thrive, doctors are becoming convinced that a one-drug-one-cancer approach is not sufficient. Just as AIDS physicians currently use a multi-drug approach to attack HIV at different stages of its life cycle, so too are cancer doctors beginning to surround tumor cells with combinations of agents that can weaken a growing cancer by chipping away at its life-support systems.

Already it is clear that the nature of those support systems is more important than where in the body the cancer originated. "The source of the cancer becomes less of an issue over time than trying to understand the signaling pathways the cell is using," says Dr. James Abbruzzese of M.D. Anderson Cancer Center. In coming years, doctors will think not of breast cancers and colon cancers but rather of growth-factor cancers and signaling cancers.

MATCHING PATIENTS

After a doctor identifies a cancer and chooses a combination of drugs to combat it, there is still no guarantee that the drugs will work. That's because no two patients are alike. Subtle differences in their genetic code often determine how well a cancer drug will be tolerated and how quickly it will be broken down in the body. Some people produce enzymes that can neutralize the more toxic side effects of anticancer drugs, while others either lack such agents or have genes that produce the opposite effect, making them more sensitive to the drug's adverse effects. Researchers at MGH, for example, found that changes in the gene coding for an enzyme involved in DNA repair can mean the difference between breast-cancer patients who can tolerate chemotherapy and those with a twofold greater chance of experiencing a toxic reaction.

When it works, the new paradigm can achieve dramatic results. Most of the newly approved drugs work in only 10% to 30% of patients, but in those patients, tumors routinely shrink to less than half their size. The number of new drugs that have been approved is small, their cost is high (at least $20,000 per cycle), and progress is slow. The five-year survival rate for all cancers is 63%, up from 51% in 1975, according to the American Cancer Society. But most of that improvement is attributed to the effectiveness of antismoking campaigns, not to better drugs. Thanks to patients like Louise Jacobs, who is helping to make new, smarter treatments part of standard cancer care, that may soon change.