In JAMA this week, Tracy Hampton reports on new findings in Science that show the most commonly mutated genes associated with pancreatic cancer encode proteins involved in chromatin remodeling. The researchers found that some pancreatic neuroendocrine tumors have mutations that are associated with better prognosis, and that some of these tumors "had mutations that altered proteins in a key regulator of cell growth and proliferation, the mammalian target of rapamycin signaling pathway," Hampton says. "These findings might be useful for identifying which patients are most likely to respond to mTOR inhibitors, which are already being clinically tested as cancer therapies."
Also in JAMA this week, researchers at the University of Maryland respond to a previously published JAMA article that suggested the cumulative effect of multiple radiologic studies puts patients at increased risk for cancer. There is no question regarding the cancer risk of very high doses of radiation, the authors of the letter write, but rather over whether the cumulative effect of low doses in the range emitted by diagnostic tools also increases the risk of cancer. "The underlying hypothesis, based on the linear-no-threshold theory, is that every x-ray photon incident on a patient increases the risk of cancer and that the effect is cumulative over the lifetime," they write, but, "the experimental data collected over the past 70 years suggests that the effect of radiation is not cumulative." Until the association between cancer and radiology is better understood, they conclude, patients should not be "scared away" from beneficial procedures.
Another letter published in JAMA this week refers to a study published in 2010 that compared mediastinoscopy and endosonography for mediastinal nodal staging of lung cancer. Although the study's authors conducted a "methodical evaluation of mediastinal staging methods in non–small cell lung cancer," there are questions that need to be answered "before considering endosonographic methods as procedures of choice for mediastinal staging in NSCLC," the letter-writers say. First, endosonographic staging with transesophageal ultrasound-guided fine-needle aspiration and endobronchial ultrasound-guided transbronchial needle aspiration are limited by equipment availability and cost. And second, the authors add, these procedure require a lot of training and expertise to perform.