June 10, 2009 (Orlando, Florida) — New research suggests that the majority of women with early-stage cervical cancer can safely undergo sentinel node biopsy to detect the spread of cancer instead of the conventional pelvic lymph node removal.
The results of the study, presented here at the at the American Society of Clinical Oncology 45th Annual Meeting, show that sentinel node biopsy was useful in providing information about lymphatic drainage that occurred through unusual pathways and detecting micrometastases and isolated tumor cells.
Lead author Fabrice Lécuru, MD, PhD, from Hôpital Européen Georges Pompido in Paris, France, explained that full pelvic lymph node removal and its associated complications might have been avoided in 81% of patients in the study if sentinel node biopsy had been used instead. "Targeted node sampling may be more relevant than full node dissection," said Dr. Lécuru.
However, an expert discussing this paper said that the technique needs to be explored further in clinical trials, and that it is not yet ready for clinical use.
Sentinel node biopsy has been used and validated for cancers of the breast and penis and malignant melanoma. It is also currently being evaluated for several other malignancies, including cancers of the vulva, cervix, head and neck, and colon. Previous studies of cervical cancer have shown that sentinel node biopsy can be used to assess cancer spread in usual areas of the pelvis, said Dr. Lécuru. The current study adds strength to the research by showing that sentinel node sampling is effective for identifying metastatic disease in unexpected or unusual regions.
An estimated 10% to 15% of patients with pN0 early cervical cancer will experience a recurrence, which could be related either to nodes missed by the dissection or located outside the dissection field, or to the failure to diagnose node metastases. Among patients with early-stage disease who undergo surgery, metastasis to the lymph nodes is detected in 10% to 20% of cases using lymphadenectomy, but the procedure can potentially cause complications.
"Sentinel node biopsy is a good option for women with cervical cancer because it enables us to remove fewer lymph nodes to get information about cancer spread, and could decrease the risk of complications from surgery, such as lymphedema," said Dr. Lécuru.
Effective for Identifying Cancer Spread to Atypical Areas
The primary objective of the study was to determine the sensitivity and negative predictive value of sentinel node dissection for evaluating local and regional node status in early cervical cancer. Secondary objectives, explained Dr. Lécuru, were to determine the rate of sentinel node micrometastasis and the frequency of unexpected lymphatic drainage patterns.
The study cohort consisted of 128 patients with stage Ia1 or Ib1 epidermoid cancer or adenocarcinoma or adenosquamous cancer, and was conducted at 7 centers in France from January 2005 to June 2007.
All of the patients had undergone a routine pelvic lymphadenectomy, with or without para-aortic lymphadenectomy. Selective sentinel node identification and dissection was performed using a combined approach of radioactive technetium tracing and blue-dye labeling to identify sentinel nodes in pelvic and para-aortic territories. Detection in an unusual territory was defined as sentinel nodes outside the ilio-obturator region.
One or more sentinel nodes were detected in 98.4% of the cohort and, in 48 women (37.5%), at least 1 node was detected in an unusual territory. The researchers identified 26 positive sentinel nodes in 21 patients (16.4%), of whom 8 (38%) had macrometastases, 7 (33%) had micrometastases, and 6 (29%) had isolated tumor cells. Of the 26 nodes, 7 (27%) were detected only by immunohistochemistry. There were no false negatives in the cohort, and node metastasis was not detected in the majority of patients (n = 104; 81.2%).
Overall, sensitivity was 91.3% (95% confidence interval [CI], 71.9% - 99%) and negative predictive value was 98.1% (95% CI, 93.2% - 99.8%).
"Targeted node sampling may be more relevant than full node dissection," said Dr. Lécuru, and could improve nodal staging of early cervical cancer. Sentinel node detection added information in 39.8% of the patients, showing that drainage occurred through unusual pathways or detecting metastasis using immunohistochemistry.
The "sentinel node technique could improve nodal staging of early cervical cancer," he concluded.
Not Ready for Clinical Use
However, Ate van der Zee, MD, from University Hospital Groningen in the Netherlands, who served as a discussant of the paper, felt that there were still too many unanswered questions. He expressed concern about the reproducibility of sentinel node detection in cervical cancer and whether it was safe to omit lymphadenectomy, among other issues.
"There are really some issues about the technique for sentinel detection in cervical cancer," he said. Standard procedures have not yet been established, such as where and how deep to inject, which tracers should be used, and who should perform the procedure.
The study was also underpowered, and the significance of isolated tumor cells and/or micrometastasis remains to be established, he explained.
"At the present time, in patients with early-stage cervical cancer, I think that sentinel node detection should only be performed within the protection of clinical trials," he said.
The study was funded by the French National Institute of Cancer. Dr. Lécuru and Dr. van der Zee have disclosed no relevant financial relationships.
American Society of Clinical Oncology (ASCO) 45th Annual Meeting: Abstract CRA5506. Presented May 31, 2009.
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