In the phase II GROINSS-V II study reported in the Journal of Clinical Oncology, Oonk et al found that inguinofemoral radiotherapy is a safe alternative to inguinofemoral lymphadenectomy in women with early-stage vulvar cancer and sentinel node micrometastasis but was associated with a higher recurrence rate among those with sentinel node macrometastasis.

Study Details

Between December 2005 and October 2016, the study registered 1,535 eligible patients from sites in 11 countries. Women had to have early-stage vulvar cancer (diameter < 4 cm) without signs of lymph node involvement on imaging, and also had to have undergone primary surgical treatment (local excision with sentinel node biopsy).

Those with sentinel node involvement (metastasis of any size) were to receive inguinofemoral radiotherapy (total = 50 Gy). The primary endpoint was isolated groin recurrence rate at 24 months.

Key Points

Overall, among the 1,535 eligible women, 322 (21.0%) had sentinel node metastases. In June 2010, the study stopping rule for recurrence was put into effect, when 10 of the first 91 sentinel node–positive patients had an isolated groin recurrence; of these, 9 had sentinel node metastases > 2 mm and/or extracapsular spread.

A protocol amendment directed that patients with sentinel node metastases > 2 mm (macrometastases) undergo standard of care with inguinofemoral lymphadenectomy and that those with metastases ≤ 2 mm (micrometastases) continue to receive inguinofemoral radiotherapy.

Among 160 patients with sentinel node micrometastases, 126 received inguinofemoral radiotherapy. In these patients, the isolated groin recurrence rate at 24 months was 1.6% (95% confidence interval [CI] = 0%–3.9%).

Among 162 patients with sentinel node macrometastases, the isolated groin recurrence rate at 24 months was 22.0% (95% CI = 10.5%–33.5%) in those who received inguinofemoral radiotherapy vs 6.9% (95% CI = 2.0%-11.8%) in those who underwent inguinofemoral lymphadenectomy (P = .011).

Treatment-related morbidity after radiotherapy was less frequent vs inguinofemoral lymphadenectomy. For example, edema at > 6 and > 12 months was observed in 16.4% vs 32.0% and 10.7% vs 22.9% of patients, respectively. Recurrent erysipelas was observed in 13.6% vs 16.6%.

The investigators concluded, “Inguinofemoral radiotherapy is a safe alternative for inguinofemoral lymphadenectomy in patients with sentinel node micrometastases, with minimal morbidity. For patients with sentinel node macrometastasis, radiotherapy with a total dose of 50 Gy resulted in more isolated groin recurrences compared with inguinofemoral lymphadenectomy.”

Maaike H. M. Oonk, PhD, of the Department of Obstetrics and Gynaecology, The University Medical Center Groningen, the Netherlands, is the corresponding author for the Journal of Clinical Oncology article.  

Disclosure: The study was supported by the Dutch Cancer Society and NRG Oncology. For full disclosures of the study authors, visit ascopubs.org.