Cancer Drug May Enable Recurrence

When glial cells in the brain or spine turn cancerous, a common therapy is surgical removal of the tumor followed by chemotherapy with temozolomide. The drug has been used for decades but in some cases may do more harm than good, note researchers led by Joseph F. Costello and Barry S. Taylor of the University of California, San Francisco. They discovered that for patients with some types of low-grade glial cell tumors, for which life expectancy averages seven years, temozolomide treatment is associated with recurrence of high-grade tumors, from which patients survive for only about one year (Science 2013, DOI: 10.1126/science.1239947). The team studied the mutated genomes of 23 excised tumors and compared them with the genomes of tumors that recurred in the same patients. Of the patients initially treated with temozolomide, 60% had recurring tumors that were hypermutated and more deadly than the original tumors. Because temozolomide is a mutagen—it makes adducts with DNA bases—the drug may be enabling the genetic changes that turn a low-grade tumor into a recurring high-grade tumor, the researchers conclude.