Inguinofemoral radiotherapy is a safe alternative to inguinofemoral lymphadenectomy in patients with vulvar cancer and sentinel node (SN) micrometastasis, according to research published in the Journal of Clinical Oncology.

On the other hand, lymphadenectomy should remain the standard care for patients with SN macrometastasis, according to researchers.

The researchers came to these conclusions based on results of the phase 2 GROINSS-V-II trial. The study included 1535 eligible patients with early-stage vulvar cancer (diameter less than 4 cm) who had no signs of lymph node involvement at imaging.


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All patients underwent local excision with SN biopsy. Patients who had SN metastasis of any size were then assigned to receive inguinofemoral radiotherapy at 50 Gy.

Results of an interim analysis prompted a protocol change allowing only patients with SN micrometastasis to receive inguinofemoral radiotherapy. Patients with SN macrometastasis were treated with lymphadenectomy, which was combined with adjuvant radiotherapy only when there was metastasis in more than 1 lymph node and/or extracapsular spread.

In all, 1213 patients (79.0%) were SN negative and 322 (21.0%) had SN metastasis.

Of the SN-positive group, 160 patients had micrometastasis. In this subgroup, 126 patients received inguinofemoral radiotherapy, 16 underwent lymphadenectomy, and 18 patients had no further treatment after SN removal.

At 2 years, the rate of isolated groin recurrences was 3.8% in the entire cohort with SN micrometastasis. The 2-year groin recurrence rate was 11.8% in patients who had received no adjuvant treatment and 1.6% in patients who had received radiotherapy (P =.006).

There were 162 patients with SN macrometastasis, 51 of whom received radiotherapy and 6 who received no further treatment after SN removal. Of the 105 patients who underwent inguinofemoral lymphadenectomy, 59 also received adjuvant radiotherapy.    

The groin recurrence rate at 2 years was 12.2% for all patients with SN macrometastasis. The rate was 22.0% in patients who underwent inguinofemoral radiotherapy and 6.9% in patients who underwent lymphadenectomy with or without adjuvant radiotherapy (P =.011).

The estimated rate of disease-specific death at 2 years was 2.1% for SN-negative patients, 6.5% for patients with SN micrometastasis, and 25.5% for those with SN macrometastasis (P <.0001). The overall survival rate at 2 years was 95.2% for SN-negative patients, 88.3% for patients with SN micrometastasis, and 69.3% for those with SN macrometastasis (P <.0001).

The toxicity of radiotherapy was acceptable, according to the researchers. They added that treatment-related morbidity was observed less frequently with radiotherapy than with lymphadenectomy.

Lymphedema at 6 months occurred in 5.1% of patients who had SN biopsy alone, 16.4% of those who had radiotherapy, and 32.0% of those who underwent lymphadenectomy with or without adjuvant radiotherapy. Recurrent erysipelas was observed in 6.6%, 13.6%, and 16.6%, respectively.

The researchers concluded that inguinofemoral radiotherapy could spare vulvar cancer patients with SN micrometastasis the morbidity of lymphadenectomy. The team recommended implementing inguinofemoral radiotherapy in treatment guidelines for vulvar cancer.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Oonk MHM, Slomovitz B, Baldwin PJW, et al. Radiotherapy versus inguinofemoral lymphadenectomy as treatment for vulvar cancer patients with micrometastases in the sentinel node: Results of GROINSS-V II. J Clin Oncol. Published online August 25, 2021. doi:10.1200/JCO.21.00006