Hospitals with the highest proportion of patients with 12 or more lymph nodes examined tended to treat lower-risk patients and have a higher volume of surgery. After adjusting for these factors, the researchers found no statistically significant relationship between the number of lymph nodes examined and patients' survival after surgery.
The idea of examining lymph nodes to estimate survival does make sense, experts say. That's because death is more likely if the cancer spreads beyond the colon, and the route of spread is typically through the lymph nodes.
However, Wong and her colleagues found that hospitals in the study tended to find the same number of lymph nodes positive for cancer, no matter how many nodes they examined.
There are several possible explanations for this seeming paradox, including individual variations in dissection or surgical techniques, Wong said. More studies looking at further clinical details may get an answer, she said.
Meanwhile, Wong said, the findings indicated a need to reconsider the 12-node rule, because there is a limit to the resources that can be expended per patient, she said. "If we spend a lot of resources to exact the 12-node exam as the standard of care, we're going to miss the opportunity to improve in other ways," she said.
It would be a mistake to focus entirely on this one indicator of quality, she said.
"Further studies are important, but what we need are better quality indicators," Wong said. She said she had no immediate suggestions about the sort of characteristics that should be examined, except that "we need to look at broader indicators."
For her part, Baxter said that perhaps too much emphasis was being placed on node numbers and diagnoses.
"I don't think setting benchmarks for the number of nodes to be examined will change the outcome for a substantial number of patients," she said. "We should concentrate on th
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