Wui-Jin Koh, MD
A new NCCN guideline for the management of vulvar cancer outlines the use of resection, radiation therapy, and chemotherapy based on disease site and stage, recognizing that only 2 randomized treatment trials have been completed.
“We are fortunate to be informed by a handful of prospective observational studies,” said Wui-Jin Koh, MD, who presented the new guideline at the 2016 NCCN Annual Conference.1
One underlying principle of the guideline is that early-stage disease can often be cured by resection alone. An evolution from an extensive “Halstedian” approach to a more limited, tailored surgery has taken place.
In the guideline, treatment planning issues are considered separately for the primary site and the groin. This construct is driven by a core of observations. In most series, metachronous groin failure (failure after initial primary treatment) occurs early, at a median of 6 to 8 months, “and they’re rarely curable,” said Koh, a professor of Radiation Oncology at the University of Washington.
“On the other hand, local vulvar failures occurring in a primary site [in the labia] may occur later on in treatment and can often be cured by additional surgery. In fact, there is a thought that these are not actually true occurrences as opposed to re-occurrences.”
Patients can develop a second vulvar cancer, not dissimilar to patients with head and neck cancer, who have an elevated risk of lung cancer.
Observation (or adjuvant radiotherapy based on other risk factors) is recommended for patients with negative margins for invasive disease after excision. If the patient has positive margins for invasive disease, the guideline recommendation is for re-excision with adjuvant radiation. Radiation should be used judiciously.
“Only if patients have positive margins or have unresectable primary disease do we routinely recommend radiation in the guidelines,” Koh said.
Lymph Node Evaluation
Sentinel lymph node (SLN) evaluation informs prognosis. In patients with unifocal disease <4 cm, the rate of groin relapse is <3% in patients with negative SLN evaluation.2
The false-negative predictive value of negative SLN evaluation is 2%.3
If the lymph node evaluation is negative, no adjuvant therapy to the node is recommended. With 2 or more positive lymph nodes, the recommended adjuvant therapy is radiation, typically with concurrent chemotherapy (category 1 for radiation).
If patients undergo SLN biopsy, the guideline diverges on adjuvant therapy based on size of SLN metastasis. “If their SLN is <2 mm in size for positive, then we believe that adjuvant radiation is appropriate treatment,” he said. “But based on the evolving GROINSS V study,4
that if the SLNs are >2 mm…they should undergo a completion inguinofemoral node dissection, followed by radiotherapy with or without chemotherapy.”
For early-stage tumors, adjuvant radiotherapy is an effective treatment modality that significantly decreases recurrence, especially in surgically resected groins, and leads to improvement in relapse-free survival and overall survival. The greatest independent predictor of groin relapse is groin node involvement at initial presentation.
“We try as much as possible to avoid radiation to the vulva itself because that is not an area that tolerates radiation well, and it may actually affect the natural history of disease and make pick up of late recurrences or re-occurrences more difficult,” said Koh.
Locally Advanced Disease
The term “locally advanced disease” applies to patients who cannot undergo surgery with visceral sparing intention. In these patients, neoadjuvant radiotherapy, typically concurrent with platinum-based radiosensitizing chemotherapy, results in significant clinical and pathologic response, allowing for reduced-scope or non-extenterative surgery, with preservation of function.5
Chemotherapy in addition to concurrent radiation may provide additional therapeutic benefit, according to the guideline, especially in advanced unresectable disease. It may also help address systemic risk in patients with multiple positive lymph nodes.
There is an option for inguinofemoral lymph node dissection because whether radiation by itself can sterilize disease in the surgically unresected groin is still unclear.