International Journal of Radiation Oncology*Biology*Physics
Clinical investigationsRectumImpact of preoperative radiation for rectal cancer on subsequent lymph node evaluation: A population-based analysis
Introduction
Rectal cancer is common and is associated with statistically significant morbidity and mortality (1). The traditional treatment has relied on radical resection. Dissection of lymph node-bearing tissue along with the rectum enables the surgeon to remove any occult direct extension and metastasis to the mesorectum and also ensures adequate staging. Recent studies have identified the prognostic significance of the number of nodes excised by the surgeon and then examined by the pathologist (2, 3, 4, 5, 6, 7, 8, 9, 10). In fact, the International Union Against Cancer requires the presence of at least 12 negative nodes in the surgical specimen to confirm adequate staging in node-negative patients (11). This requirement for 12 nodes has been accepted as the standard in the treatment of rectal cancer (by a panel of experts sponsored by the National Cancer Institute) (12).
In 1990, the National Institutes of Health Consensus Conference established adjuvant radiotherapy (RT) with chemotherapy as the standard of care to achieve regional control of Stage II and III rectal cancer (13). Preoperative RT may well confer real benefits. Its use is significant and may be increasing. In fact, an increasing body of data suggests the superiority of preoperative RT combined with chemotherapy in terms of local control, disease-free survival, and the ability to perform sphincter-sparing resection (14, 15, 16). However, the impact of preoperative RT on pathologic lymph node evaluation has not yet been quantified. Evidence indicates that preoperative RT may decrease the number of analyzable nodes that the surgeon and pathologist are able to retrieve (17, 18, 19). Given the increasing importance of preoperative RT, we designed our study to examine its effect, in a population-based fashion, on pathologic nodal evaluation after radical resection for rectal cancer.
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Data
We used the data from the Surveillance, Epidemiology and End Results (SEER) cancer registry, a population-based registry sponsored by the National Cancer Institute. SEER collects information on cancer incidence and survival from 11 population-based cancer registries and three supplemental registries; these registries include about 14% of the U.S. population (20). The information collected by SEER includes patient characteristics, county of residence, primary tumor site, morphologic features,
Results
In our 3-year study period, 5647 patients (58% male) with rectal cancer met our selection criteria. In 5317 patients (94%), the radiation sequence with respect to surgery could be determined. Of these 5317 patients, 1034 (19.5%) had undergone preoperative RT (Table 1). Patients who underwent preoperative RT tended to be younger (average age, 61 years) than those who did not undergo preoperative RT (average age, 67 years). In addition, the men were more likely to undergo preoperative RT (22% of
Discussion
For patients with rectal cancer who undergo primary surgical resection, the number of lymph nodes found and analyzed by the pathologist can have a major impact on outcome (2, 3, 4, 5, 6, 7, 8, 9, 10). For patients with T1 or T2 rectal cancer, who have no lymph node involvement, no additional therapy is usually administered. However, if lymph nodes are involved, adjuvant RT and chemotherapy are generally recommended. In addition, positive lymph nodes have a substantial effect on the patient's
Conclusion
Overall, our study demonstrated that few rectal cancer patients underwent adequate LNS. In light of the impact of nodal retrieval on postoperative care and prognosis, many patients in the United States would benefit from improvements in prevailing surgical and pathologic practices. Various professional organizations must help ensure that patients receive proper surgical care and pathologic assessment. For rectal cancer patients who undergo preoperative RT, additional research is crucial to
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Supported in part by the University of Minnesota Cancer Center.