"Look under the microscope at the breast cancer of 10 women and they all look the same," says Judy Garber, M.D., president of the American Association for Cancer Research (AACR) and director of the Center for Cancer Genetics and Prevention at the Dana-Farber Cancer Institute in Boston. "Yet each will react differently. We used to think of cancer by organ. Now we must think about it as molecules in order to target the treatment specific to that person's cancer."
Most cancers have yet another means of confounding doctors: The mutated cells adapt, particularly under the stress of treatment, and they often adapt differently in any two people.
Despite these challenges, most researchers would agree that their understanding of cancer improved significantly in the years following the National Cancer Act.
An unhealthy attachment
A case in point is the drug that Stutman takes — Gleevec — which has transformed gastrointestinal stromal tumors (GIST) and another form of cancer — chronic myelogenous leukemia (CML) — from fatal illnesses into chronic ones.
The first breakthrough came in 1973, when Janet Rowley, M.D., at the University of Chicago, showed that in those with CML, chromosome 22 attaches to chromosome 9. It would be another 10 years before Dutch and American researchers discovered the full significance: The 22-9 attachment had prompted two genes to fuse. The resulting "oncogene" triggered the uncontrolled cell division of CML.
All of this was great for the textbooks. What made a difference to CML and GIST sufferers was the discovery by Brian Druker, M.D., of the Oregon Health and Science University in Portland, of a molecule that would block a protein produced by the gene, and turn off its replication switch. The cancer community had its long-sought-after magic bullet. Gleevec, the drug that emanated from Druker's research, attacked the root of the problem but left the healthy cells alone.
The FDA approved Gleevec in 2001. Since then, similar drugs have been developed for other forms of cancer, including melanoma and lung cancer. But, as Schilsky says, "These are not cures. Over time, the cancers develop new mutations or immunity to the drugs. We now have a second generation of drugs for those who are Gleevec resistant."
While drugs like Gleevec may offer the best hope for cancer sufferers, advancements in surgery and radiation have also improved survival rates. Radiation, for instance, is much more precise. Rather than blasting the tumor from all sides indiscriminately, which destroys healthy as well as diseased tissue, IMRT, or intensity-modulated radiation therapy, allows doctors to target just the tumor. "We can't eliminate side effects," says Allan Lichter, M.D., chief executive officer of the American Society of Clinical Oncology. "Radiation kills cells indiscriminately. But what we are doing better is keeping the dose to normal cells as low as possible and the dose to the bad guys as high as we can."
So where does that leave us today? Are we close to finding a cure for cancer?