DRUG RESISTANCE keeps cancer chemotherapy from working the way it should. Because chemotherapy employs drugs that kill tumor cells preferentially, it should eradicate the malignancy before irreversible damage is done to the host. But it fails to do so when, at concentrations that are tolerable to normal host tissue, cytotoxic agents are no longer able to dispatch tumor cells.
Recently 24 investigators, who have spent many years trying to determine how and why tumor cells can adapt and thrive in the presence of toxic agents, spent two days discussing their findings. The occasion was the Ninth Annual Bristol-Myers Symposium on Cancer Research in Washington, DC, the home of the organizing institution, the Vincent T. Lombardi Cancer Research Center, Georgetown University School of Medicine and Hospital.
Several themes surfaced: That the first evidence of drug resistance is often a change in tumor-cell chromosomes; that a single mechanism is often responsible for