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November 13, 2007

Quality indicator for colon cancer surgeries questioned: U-M study

Having larger numbers of lymph nodes examined for cancer is not necessarily linked to better survival rates or higher quality surgery

ANN ARBOR, MI – Detecting cancer in lymph nodes following surgery lets doctors determine how advanced the cancer is and whether chemotherapy is appropriate. Using the number of lymph nodes examined after colon cancer surgery, or colectomy, as a hospital quality indicator is gaining momentum. In fact, the examination of 12 lymph nodes as a quality indicator after colectomy was recently endorsed by the National Quality Forum, a respected organization that focuses on health care quality measurement and reporting, and is rapidly being adopted by major payers in pay for performance initiatives. But is more necessarily better?

Dr. Sandra WongIn a study appearing in the Nov. 14 issue of the Journal of the American Medical Association, researchers at the University of Michigan Medical School find that examining a specific number of lymph nodes after a colectomy to remove part or all of the colon is not associated with the length of patient survival.

“Hospitals vary widely in the number of lymph nodes examined.  However, it appears that the number of lymph nodes that hospitals examined following colon resection did not influence how long patients lived,” says first author Sandra Wong, M.D., M.S., a U-M surgical oncologist.

In order to design a study reflective of the hospital perspective, Wong and her colleagues used the National Surveillance Epidemiology and End Results (SEER) Medicare-linked database from 1995 to 2005 to identify all patients undergoing colectomy for colon cancer that has not spread to other organs. Hospitals where these 30,625 patients underwent surgery were then divided into four groups based on the proportion of patients with 12 or more lymph nodes examined. Researchers then assessed late survival rates for each hospital group, adjusting for potentially confounding patient and clinician characteristics.

Hospitals with the highest proportions of patients who had 12 or more lymph nodes examined tended to treat lower-risk patients and had substantially higher procedure volume. After adjusting for this, too, the researchers found there was no statistically significant relationship between hospital lymph node examination rates and survival after surgery.

“These findings suggest that the momentum to implement a 12-node minimum as a quality indicator for hospitals performing colectomies for colon cancer should be slowed to allow for further investigation,” says Wong, a member of the U-M Comprehensive Cancer Center. “Everyone is vested in improving cancer care, but at the end of the day, there are only so many resources we can use for this.  If we spend a lot of resources to enact the 12-node exam as the standard of care, we’re going to miss the opportunity to improve in other ways.”

Wong and her colleagues also found that, regardless of how many lymph nodes hospitals examined, they tended to find the same number of nodes positive for cancer, with similar rates of chemotherapy and survival for their patients. She says there are a number of reasons that may account for this seeming paradox, including individual variations in surgical or dissection techniques. Other factors may have influence, too, including race or tumor location, leading the researchers to call for further studies that include more clinical detail.

“Lymph node counts do not identify hospitals with better results in treating colon cancer.  Patients, physicians, and payers need more useful quality indicators for this condition,” says the study’s senior author, John Birkmeyer, M.D., who directs the Michigan Surgical Collaborative for Outcomes Research and Evaluation. This consortium of surgeons and other clinical scientists shares common interests in health services research, quality improvement and policy issues in surgery, including development of new and better measures of quality for both surgeons and hospitals.

The study was funded by the National Cancer Institute. Additional co-authors are Hong Ji, M.S., Brent Hollenbeck, M.D., M.S., Arden Morris, M.D., M.P.H., and Onur Baser, Ph.D., University of Michigan Medical School.

Reference: JAMA, November 14, 2007 – Vol. 298, No. 18, 2149-2154.

Written by Mary Beth Reilly


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