SAN DIEGO – Lymph node removal during gastrointestinal cancer surgery remains underperformed in a large proportion of patients in the United States, although the median number of resected nodes increased from 1998 to 2009.
Those are the key findings of a 10-year analysis of medical records from the National Cancer Institute’s Surveillance Epidemiology and End Results (SEER) database.
Several reports in the literature show a correlation between long-term survival and the removal of possibly metastatic lymph nodes along with the cancerous organ during surgery, Dr. Attila Dubecz explained in an interview at the annual Digestive Disease Week. There are also survival differences based on sex, race or poverty status, and differences in lymph node removal between these groups in certain cancer types, he said. "We wanted to determine if these differences are more related to cancer types therefore the type of operation, for example or to these underprivileged groups."
Using SEER data from 1998 to 2009, Dr. Dubecz of Klinikum Nürnberg (Germany) and his colleagues identified 326,243 patients with a surgically treated GI malignancy. This included 13,165 malignancies in the esophagus, 18,588 in the stomach, 7,666 in the small bowel, 232,345 in the colon, 42,338 in the rectum, and 12,141 in the pancreas.
Adequate lymphadenectomy was defined as removal of at least 15 lymph nodes for cancer of the esophagus and the stomach; at least 12 for cancer of the small bowel, colon, and rectum; and at least 15 for cancer of the pancreas. The researchers evaluated the median number of lymph nodes removed and the prevalence of adequate and/or no lymphadenectomy for each cancer type over the 10-year period. They used multivariate logistic regression analysis to identify factors predicting adequate lymphadenectomy.
Dr. Dubecz, a surgeon, reported that the median number of excised nodes improved over the 10-year period in all types of cancer: from 7 to 13 in esophageal cancer, 8 to 12 in stomach cancer, 2 to 7 in small bowel cancer, 9 to 16 in colon cancer, 8 to 13 in rectal cancer, and 7 to 13 in pancreatic cancer.
In addition, the percentage of patients with an adequate lymphadenectomy (a median of 49% for all types) steadily increased and those with zero nodes removed (a median of 6% for all types) steadily decreased in all types of cancer, "although both remained far from ideal," the researchers wrote.
By 2009, the percentage of patients with adequate lymphadenectomy was 43% for esophageal cancer, 42% for stomach cancer, 35% for small bowel cancer, 77% for colon cancer, 61% for rectal cancer and 42% for pancreatic cancer. Men, patients older than age 65, or those undergoing surgical therapy earlier in the study period and living in areas with high poverty rates were significantly less likely to receive adequate lymphadenectomy (P less than .0001 for all groups).
"The main surprise was that race was an insignificant factor, and gender, age, and socioeconomic differences between the groups with adequate versus inadequate lymph node dissection were also much less [than] between the groups of different cancer types," Dr. Dubecz said at the annual meeting of the Digestive Disease Week.
Dr. Dubecz acknowledged certain limitations of the study, including the potential for misclassification of patient information in the SEER database. "Furthermore, despite being advocated by several practice organizations and consensus panels, the definitions of adequate lymphadenectomy used in this study are not universally accepted," he noted. "Third, our analyses are limited to the available variables in the SEER database with no information regarding patient insurance status, comorbidities, body mass index, or [neo]adjuvant chemotherapy, which could influence lymph node dissection and the disparities."
Dr. Dubecz said he had no relevant financial disclosures.