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Lymph node evaluations in colorectal cancer are still falling short of recommended standards, two teams of researchers found in separate investigations.
Dr. Ashwani Rajput reported that fewer than half of colorectal cancer patients in a large population-based sample had 12 or more lymph nodes dissected and evaluated, as is recommended by the American College of Pathology.
He and his colleagues analyzed the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database of 14,000 stage I-III colorectal cancer patients diagnosed in 2002. The three cancer stages were equally represented among 7,676 SEER database patients who did not have 12 lymph nodes evaluated.
By comparison, the 12-plus lymph node standard was achieved in 90% of 345 patients treated at the eight National Comprehensive Cancer Network (NCCN) centers that participated in the study reported by Dr. Rajput, an attending surgeon at Roswell Park Cancer Institute in Buffalo, New York. These patients had newly diagnosed stage I-III colon or rectal cancer and underwent primary surgery in 2005-2006.
The investigators compared the NCCN patients with the SEER patients.
Altogether, 89% of the NCCN sample but only 45% of the SEER sample had at least 12 lymph nodes evaluated.
Dr. Rajput called for more intensive education of surgeons and pathologists to increase compliance with the recommended standard. "We need to make sure that surgeons are doing the appropriate resections and that pathologists are spending the appropriate time to find the number of lymph nodes in each specimen," he said in an interview.
The second study also found that the proportion of colorectal cancer patients receiving appropriate sampling is unacceptably low, and suggested that staging may suffer as a result. Dr. Qian Cai and her colleagues gathered SEER data from 1990 to 2001 on 221,000 patients aged 18 years or older. Multivariate logistic regression was used to assess the association between staging and sampling 12 or more vs. fewer than 12 lymph nodes.
Overall, about 35% of colorectal patients had 12 or more lymph nodes assessed. Among these patients, more than one-third had stage III colorectal cancer. By comparison, less than 20% of patients with fewer than 12 lymph nodes sampled were found to have stage III disease, according to Dr. Cai, a researcher with Abt Associates Inc., in Lexington, Mass.
Patients who had 12 or more lymph nodes sampled were 31% more likely to be diagnosed with stage III rather than stage II colorectal cancer (P = .001), compared with patients who had fewer than 12 nodes sampled, Dr. Cai said. Also, patients with the appropriate sampling rate were 41% more likely to have been diagnosed with stage II colorectal cancer than stage I, as compared with the sub-12 node group.
Because patients who had 12 or more lymph nodes sampled were significantly more likely to be diagnosed with more advanced disease, they may receive more aggressive treatment, Dr. Cai suggested.
"Greater adherence to the current NCCN recommendations for nodal sampling should lead to improved accuracy in colorectal staging," she stated with her colleagues. "And improved staging accuracy, in turn, gives clinicians the opportunity to manage treatment more appropriately via adjuvant chemotherapy or other interventions."
Dr. Mitchell C. Posner, discussant on the two poster studies, observed, "Adherence to the guideline for lymph node retrieval greater than or equal to 12 lymph nodes clearly is more likely in NCCN centers, remains an elusive goal for most patients in this country who have resected colorectal cancer, and improves staging accuracy."
"We get it. We agree that 12 lymph nodes is the benchmark that we should use, and I challenge that we should not need to write any more papers about this 12-lymph node target," added Dr. Posner, the Thomas D. Jones Professor of Surgery and chief of general surgery and surgical oncology at the University of Chicago.
Although that goal had not been reached, taken together, the two current studies suggest that progress is being made, he said.
Rajput A. et al. Meeting the 12 lymph nodes (LN) benchmark in colorectal cancer surgery: A comparison of NCCN and SEER data. Abstract 4015.
Yeh Y. et al. Assessing 12 or more lymph nodes increases the proportion of stage III disease in colorectal cancer (CRC): Evidence from the Surveillance, Epidemiology and End Results (SEER) cancer registry. Abstract 4016.
Commentary |
At least 12 lymph nodes are almost always removed and examined as part of an oncologic resection in patients whose operations take place in National Comprehensive Cancer Network Centers. In general population-based samples, this target is achieved in fewer than half of cases. With longer follow-up we will be able to link this quality indicator directly to outcomes and, thereby, better inform our field as to whether increasing the number of nodes evaluated is an important priority for cancer control. Of note, patients who had more than 12 lymph nodes sampled were 1.3 times more likely to be diagnosed with stage III than stage II colorectal cancer. The odds of being staged as III versus II increased over time. It also has been shown previously that older patients tend to have fewer nodes sampled. The proportion of colorectal cancer patients who received appropriate sampling with the most recent data available is unacceptably low. A significant increase in stage III patients who had more than 12 lymph nodes sampled may increase the proportion of patients considered for aggressive treatments. Because the accuracy of staging is improved with nodal sampling, clinicians will be better positioned to treat their patients if lymph node sampling recommendations are followed. That we disseminate this information to the community practice setting is extraordinarily important, particularly in areas where there is a relatively low volume of colorectal cancer surgery. The general surgical and pathology specialties need to monitor this carefully. — Stuart M. Lichtman, M.D.
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