Surgical Assessment of Lymphatic Spread in Endometrial Cancer: A New Paradigm
Surgical Assessment of Lymphatic Spread in Endometrial Cancer: A New Paradigm
Abstract & Commentary
By Robert L. Coleman, MD, Associate Professor, University of Texas; M.D. Anderson Cancer Center, Houston, is Associate Editor for OB/GYN Clinical Alert.
Dr. Coleman reports no financial relationship to this field of study.
Synopsis: Accurate surgical assessment in patients considered "at risk" for lymphatic metastases might prevent over- and under-treatment. Not all patients require formal dissection.
Source: Mariani A, et al. Gynecol Oncol. 2008; 109:11-18.
The current classification for endometrial cancer incorporates the histological assessment of the regional lymph node to assign stage. In addition, many clinicians believe formal resection of these lymphatic tissues impart therapeutic efficacy despite lack of confirmation in randomized trials. The current study prospectively evaluates a staging algorithm in which lymphadenectomy was to be avoided in low risk patients (ie, intraoperatively, those with primary tumor diameter of 2 cm or less, grade 1 or 2 endometrioid histology and myometrial invasion of 50% or less) whereas all others underwent a formal lymphatic dissection. The latter was standardized by surgical technique (removal of all node-bearing fatty tissue from the obturator foramen to the renal vessels), and labeling the location of resected tissues. Adequacy of resection involved consistency in node counts among surgeons and documentation of samples from 4 pelvic locations and 2 para-aortic (above and below the inferior mesenteric artery [IMA]) on each side. A blinded quality control measure (node counts per surgeon) was also imparted to demonstrate homogeneity of harvesting over two time segments in the study.
Over a 3-year period, 422 consecutive patients were entered into the prospective surgical trial. Lymphadenectomy was deemed unnecessary in 27% (all low risk). Of those undergoing lymphatic dissection, 22% were found with nodal disease. Metastases to both pelvic and para-aortic nodes was identified in 51%, pelvic only in 33% and isolated to the para-aortics in 16%. Overall, the para-aortic region was involved in two-thirds of the nodal disease cases. Anatomically, three-quarters of these para-aortic metastases were above the IMA. Of interest, the majority of these cases involved negative nodes in the ipsilateral common iliac or below IMA locations. The authors conclude that formal exploration and resection of the sub-renal para-aortic nodes is necessary in patients undergoing lymphadenectomy, while the procedure can be safely avoided in low risk patients.
Commentary
Surgical staging classification by FIGO in endometrial cancer is now 2 decades old. It is then surprising that just 30% of primary endometrial cancer patients in this country receive surgical staging, that for whom the procedure is needed and exactly what constitutes "surgical staging" is still debated, that the therapeutic impact of nodal resection is undocumented convincingly, and that the role of surgery and adjuvant therapy is not standardized. In part, some of this lack of knowledge is related to process—not that these questions haven't been raised or studied (even in randomized clinical trials), but that the one aspect defining patient categorization (surgical staging) hasn't been standardized. Evidence of this issue is readily apparent from published staging guidelines, which specifically describe the para-aortic dissection as removal of that tissue between the mid common iliac vessels and the IMA. Based on the current study, 12% of all patients undergoing lymphadenectomy would have been misclassified as having had a "negative" para-aortic assessment. Some of this is also based on the belief that isolated para-aortic disease is extremely uncommon; however in this current study nearly 1 in 6 patients with metastatic disease had isolated disease in the para-aortic region. Precision in describing the nodal status of patients, particularly with otherwise limited clinical disease, is an important first step in assessing the impact of an adjuvant strategy, like radiation or chemotherapy.
The ASTEC surgical trial was conducted to assess formally the specific impact surgical staging had on survival in women with endometrial cancer. Unfortunately, a standardization process (and quality control) of the surgical staging was not required nor were the explicit recommendations for adjuvant therapy, both of which will make the results of the trial, when available, difficult to interpret. An important feature of the current article is that quality control can successfully normalize the procedure. It is hoped that such standards can be adopted so that the next 2 decades will usher in focused investigation precisely defining optimal therapy for our patients with endometrial cancer.
Additional Reading
- McMeekin DS, et al. Nodal distribution and its significance in FIGO stage IIIc endometrial cancer. Gynecol Oncol.2001;82:375-379.
- Mariani A, et al. High-risk endometrial cancer subgroups: candidates for target-based adjuvant therapy. Gynecol Oncol. 2004;95:120-126.
- Creutzberg CL. Lymphadenectomy in apparent early-stage endometrial carcinoma: do numbers count? J Clin Oncol. 2005;23:3653-3655.
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