In JAMA this week, researchers in Maryland and Minnesota present a study on the association between lymph node evaluation for colon cancer patients and node positivity over the past two decades. Among colon cancer patients, those with better survival are usually the ones with more lymph nodes evaluated, the team writes. Clinicians presume this is because a more extensive lymph node evaluation reduces the risk that something will be missed. For this study, the researchers evaluated this association by studying data from 86,394 patients surgically treated for colon cancer from 1988 to 2008. They found that the number of lymph nodes evaluated increased as the years went by, but didn't result in a significant overall increased in lymph node positivity. The authors did find, however that "although patients with high levels of lymph node evaluation were only slightly more likely to be node positive, these patients experienced significantly lower hazard of death compared with those with fewer nodes evaluated."
In a related JAMA editorial, the University of Michigan's Sandra Wong says that with increased demand for higher-quality cancer care, quality indicators of a disease's progression and response to treatment can serve as guides for physicians as they improve care processes. However, she adds, several recent reports show that "adherence to quality indicators may not improve patient outcomes and, in fact, may result in unintended harm." A case-in-point is the above-mentioned study. Wong says that although it showed that counting more nodes didn't result in finding more patients with lymph node cancers, there was a significant association between lymph node count and survival. But, she asks, "is there value to removing nodes even when the nodes are known to be negative? Despite an association between lymph node counts and survival in colon cancer, there is little evidence that increasingly extensive lymphadenectomy results in better survival." A hazard of associated with the development and implementation of quality indicators is that there's a lack of evidence to concretely prove associations between the indicators and survival outcomes, Wong says.