Sentinel Node Concept Applies for Vulva Cancer
April 1, 2008 4 minutes read
Sentinel Node Concept Applies for Vulva Cancer
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.
Synopsis: Compared with historical rates of groin recurrence following inguinal femoral lymphadenectomy, sentinel node biopsy alone was found to be a safe alternative in patients with early stage vulvar cancer.
Source: Van der Zee A, et al. J Clin Oncol. 2008;26:884-889.
Sentinel node localization and sampling has become a standard practice in the evaluation of regional nodal status for patients with breast cancer and cutaneous melanoma. The primary purpose of the current report was to assess the safety and clinical utility of the procedure in patients with early stage vulvar cancer. To do this, the authors performed a multi-institutional observational study of women with T1 and T2 vulvar squamous cell lesions (under 4 cm) with clinically non-suspicious regional nodes. Patients were to undergo dual modality node localization (blue dye and radiocolloid injection (99Tc) with lymphoscintigraphy) with sampling of the identified sentinel node(s). Following ex vivo confirmation, the node(s) were sent to pathology for frozen section. If no metastases were identified the procedure was terminated; if metastases were identified, a formal inguinal-femoral lymphadenectomy was performed. Similarly, if final histology demonstrated metastases either by H&E staining or by immunohistochemisty, patients underwent formal groin dissection. All patients had primary surgery for control of the vulvar tumor. Early in the study, patients with multifocal disease were also included but were amended out of the study following the observance of groin recurrence in 2 of 19 such patients. The study was designed to include investigators with experience in the procedure (defined as a minimum of 10 procedures) and was controlled externally by predefined recurrence risks deemed unacceptable (8%). Early stopping rules were employed to guard against the continuance of the study in the occurrence of unacceptable groin relapse. A minimum observational period of 2 years was required for patients to be evaluable. Patients with more than 1 metastatic node or those with extranodal extension were given post-operative groin and pelvic radiation. Toxicity was recorded for all patients. Overall, 8 patients suffered groin relapse (3%) following negative sentinel node biopsy. Excluding patients with multifocal disease 6 recurrences (2.3%) were identified in 259 patients with negative sentinel node biopsy. Patients undergoing formal groin dissection were identified with higher rates of wound breakdown and cellulitis; similarly, long-term complications of recurrent erysipelas and lymphedema were statistically higher following lymphadenectomy. The authors conclude that sentinel node biopsy is associated with similar low rates of groin recurrence in patients with selected early stage vulvar cancer.
Commentary
Almost as important as the results, is the fact that this study was completed. The project is a credit to power of multi-institutional investigation. Dr. van der Zee and his colleagues are to be commended for conducting a study in a disease that, in all stages, afflicts less than 4 in 100,000 women annually and was dependent on surgeons who have overcome the inconsistency associated with the learning curve. This remarkable observational study is an important step in redefining the management for this rare malignancy.
Sentinel node investigation in vulvar cancer began in the early 90's following description in cutaneous melanoma. The concept was rational as lymphatic drainage is orderly and predictable to the ipsilateral groin for lateralized lesions and bilateral in midline lesions. Following its initial description in 9 patients with blue dye in 1994, several single institution reports have emerged, largely confirming the feasibility of the concept and adding enhancements such as radiocolloid injection, lymphoscintography and pathological processing such as step-sectioning and cytokeratin immunohistochemistry. In institutions with experienced surgeons, low rates of false negative determinations are reported. This is calculated by performing a full lymphadenectomy after sentinel node localization and comparing the histological findings in both specimens. Such a validation study is the focus of the nearly completed GOG-173. The current study, however, goes one step further in that patients with negative sentinel node sampling were simply observed, without lymphadenectomy. The low rates of groin recurrence reported suggest the procedure, when performed by experienced surgeons in selected patients, is associated with a low frequency of missing a metastatic foci in retained, non-sentinel lymph nodes. While such an occurrence can be associated with any disease site where the technique is used, the primary risk in vulvar cancer is the lack of routine adjuvant therapy in the absence of metastatic disease. The implication to patient care is profound as groin recurrence in vulvar cancer is nearly always accompanied by disease-related mortality. Nonetheless, validation and adoption will go far in reducing lifelong morbidity from formal lymphadenectomy—a 25% risk that could be largely avoided for the nearly three quarters of women in whom the extended surgery offers no benefit. The next question to be addressed is can we avert lymphadenectomy even in node positive patients? Fortunately, that hypothesis is being tested in the follow-up GROINS-II trial by these same investigators.
Suggested Reading
- Levenback C, et al. Intraoperative lymphatic mapping for vulvar cancer. Obstet Gynecol. 1994;84:163-167.
- Frumovitz M, et al. Characteristics of recurrence in patients who underwent lymphatic mapping for vulvar cancer. Gynecol Oncol. 2004;92:205-210.
- de Hullu JA, et al. What doctors and patients think about false-negative sentinel lymph nodes in vulvar cancer. J Psychosom Obstet Gynaecol. 2001;22:199-203.
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