Study Challenges Colon Cancer Surgery Follow-Up

Study Challenges Colon Cancer Surgery Follow-Up
TUESDAY, Nov. 13 (HealthDay News) -- A new study is questioningthe conventional wisdom of checking on the health of 12 lymph nodes aftercolon cancer surgery.
These post-op checks have been thought to be a good indicator ofpatient survival, but new data is casting that notion in doubt.
"What we are finding is that focusing on this quality indicator may nothave much positive value for predicting patient outcome," said the study'slead author, Dr. Sandra L. Wong, assistant professor of surgery at theUniversity of Michigan, Ann Arbor.
Wong's team published its report in the Nov. 14 issue of the Journalof the American Medical Association.
The routine examination of 12 lymph nodes after colon cancer surgeryhas been endorsed by the National Quality Forum, a respected organizationbacked by such prestigious bodies as the American Cancer Society and theAmerican Society of Clinical Oncology.
However, the Michigan study of more than 30,000 people who underwentcolon cancer surgery provided no support for the protocol.
One expert wasn't surprised by the results.
"People have been interpreting information relating the number of nodesexamined and survival in a very simplistic way," said Dr. Nancy N. Baxter,assistant professor of surgery at the University of Toronto and co-authorof an accompanying editorial. "That relationship is probably prettycomplex, due at least in part to the underlying biology of the tumor," shesaid.
Using information from the Medicare-linked National Surveillance andEnd Results data base, Wong's team divided hospitals where the surgery wasdone into four groups, based on the proportion of patients who had 12 ormore lymph nodes examined.
They then assessed patient survival rates for each group of hospitals,adjusting for patient and doctor characteristics.
Hospitals with the highest proportion of patients with 12 or more lymphnodes examined tended to treat lower-risk patients and have a highervolume of surgery. After adjusting for these factors, the researchersfound no statistically significant relationship between the number oflymph 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 spreadsbeyond the colon, and the route of spread is typically through the lymphnodes.
However, Wong and her colleagues found that hospitals in the studytended to find the same number of lymph nodes positive for cancer, nomatter how many nodes they examined.
There are several possible explanations for this seeming paradox,including individual variations in dissection or surgical techniques, Wongsaid. More studies looking at further clinical details may get an answer,she said.
Meanwhile, Wong said, the findings indicated a need to reconsider the12-node rule, because there is a limit to the resources that can beexpended per patient, she said. "If we spend a lot of resources to exactthe 12-node exam as the standard of care, we're going to miss theopportunity to improve in other ways," she said.
It would be a mistake to focus entirely on this one indicator ofquality, she said.
"Further studies are important, but what we need are better qualityindicators," Wong said. She said she had no immediate suggestions aboutthe sort of characteristics that should be examined, except that "we needto look at broader indicators."
For her part, Baxter said that perhaps too much emphasis was beingplaced on node numbers and diagnoses.
"I don't think setting benchmarks for the number of nodes to beexamined will change the outcome for a substantial number of patients,"she said. "We should concentrate on things we know will help. For example,we know that many patients with stage 3 colon cancer don't getchemotherapy." Stage 3 cancer has spread to the lymph nodes but not beyondthem.
"There is a lot of work to be done in terms of getting treatment weknow helps patients, to patients," Baxter said.
But the relationship between the number of nodes examined and patientsurvival should continue to be explored, Baxter said. "There may be someunderlying biological factor we could use," she added.
Another expert also said more research needs to be done.
"In many ways, this study confirms a lot of prior findings about lymphnodes and survival," said Dr George Chang, assistant professor of surgicaloncology at the University of Texas M. D. Anderson Cancer Center inHouston. "But it highlights the complexity of that relationship."
Even in the quarter of hospitals in which the largest number of lymphnodes were examined, "only 61 percent of patients had 12 looked at," Changsaid. "Perhaps examination of a considerably larger number is required topredict survival."
More information
There's more on colon cancer at the U.S. National Library of Medicine.