Conventional chemotherapy kills rapidly dividing cells, but targeted drugs disrupt specific molecules needed for tumor growth and spread. With some cancer types, the target is present in most patients; an example is Gleevec for chronic myelogenous leukemia. Other types require tumor analysis to screen for the specific target; about 20 percent of breast cancers, for example, are susceptible to Herceptin.
Because some mutations drive multiple types of cancer - including cancers that may not be known for having the mutation - an emerging piece of diagnostic workups involves sequencing patients' whole genomes to find targetable abnormalities. Last week, Independence Blue Cross announced it will begin covering such DNA sequencing. And last year, the National Cancer Institute launched a nationwide clinical trial, called NCI-Match, that will analyze 3,000 patients' tumors to identify unusual candidates for targeted drugs.
The cost of targeted treatments is a pressing issue. The MD Anderson study, coauthored by Fox Chase Cancer Center oncologist Daniel Geynisman, found that spending on targeted therapies soared over a decade, and accounted for 63 percent of all anticancer drug spending in 2011.
The authors concluded new cost-benefit controls were needed "to curb the escalating cost of anticancer drugs."