Sep 1, 2021
Improving care in vulvar cancer via the prospective Vulvar GROINSS VII study
This JCO Podcast provides observations and commentary on the JCO article “Radiotherapy Versus Inguinofemoral Lymphadenectomy as Treatment for Vulvar Cancer Patients with Micrometastases in the Sentinel Node: Results of GROINSS-V II” by Oonk et al. My name is David Gaffney, and I am a professor and Vice Chair of Radiation Oncology at the University of Utah. I am also Senior Director for Clinical Research at the Huntsman Cancer Institute in Salt Lake City, Utah. My oncologic specialty is radiation oncology. I have no relevant disclosures to this study.
The GROINS VII study is the successor trial of the GROINS V I trial. In the GROINSS-V I study, the authors demonstrated that omission of an inguinal femoral lymphadenectomy was safe in patients with a negative sentinel lymph node with an isolated GROIN recurrence rate of 2.3%. It also showed that with long term follow up a significant proportion of patients will recur. At 10 years local recurrence occurred in 39.5% of all patients. Although local recurrences are treated with curative intent, the disease-specific survival of these patients decreases significantly. It is important to ask if there is a dose response to radiotherapy in vulvar cancer? GOG 101 was published in 1998 and employed a split course of radiotherapy to a dose of 47.6 Gy with concurrent cisplatin and 5-FU. The complete response rate was 46.5%. The subsequent prospective phase II randomized trial, GOG 205, was published in 2012 and employed 10 Gy more of radiotherapy with weekly cisplatin to a total dose of 57.6 Gy. This study demonstrated a 78% pathologic complete response rate. Hence, by adding 10 Gy, the complete response rate increased by 30%, indicating a steep dose response. Also, by way of background, a retrospective study from MD Anderson by Stecklein et al. published in 2018 demonstrated a 3-year actuarial groin control rate of 83% with high dose conformal radiotherapy with a median dose of 66 Gy to grossly positive nodes. These data demonstrate that radiotherapy can sterilize gross disease in select circumstances.
The GROINSS-V II study was a phase II prospective study in a rare disease, and sought to answer whether radiotherapy to 50 Gy could be an effective and less morbid alternative to inguinofemoral lymphadenctomy Patients were accrued from 59 hospitals in 11 countries. Eligibility for this study were patients with tumors less than 4 cm, with negative groin nodes on preoperative CT, MRI, or ultrasound. The primary endpoint was a groin recurrence rate at 24 months. A combined technique was used to evaluate the sentinel lymph node of lymphoscintigram and blue dye. Bilateral sentinel lymph node procedures were required for midline lesions. The radiotherapy was 50 Gy in 25-28 fractions with the field size to extend to the bottom of the SI joints, including the distal external iliac lymph nodes. Greater than 1700 patients were registered. One hundred sixty patients were found to have micrometastases, that is disease less than 2 mm, whereas 162 patients were found to have macrometastases. The median size vulvar lesion for patients with negative sentinel lymph node was 18 mm, 23 mm for patients with micrometastases, and 25 mm for patients with macrometastases.
Results at 2 years demonstrated an isolated groin recurrence rate occurred in 1.6% of patients that were treated per protocol with micrometastases. Whereas patients with macrometastases had an isolated groin recurrence rate at 2 years of 12.2%. For patients with macrometastases treated with radiotherapy, the groin recurrence rate was 22%. Whereas groin failure was 6.9% for patients who had macrometastases treated with inguinal femoral lymphadenectomy and radiotherapy. For patients with macrometastases, no groin recurrences were observed in 7 patients treated with chemoradiotherapy. Among the 1213 patients with a negative sentinel lymph node, an isolated groin recurrence occurred in 31 patients for a rate of 2.7% at 2 years. For the 56 patients who suffered a groin recurrence, 31 of them died of vulvar cancer for an overall survival rate of 39% at 2 years.
This trial also looked at morbidity of patients treated with inguinal femoral lymphadenectomy versus sentinel lymph node procedure plus radiotherapy. The lower extremity edema rate was 32% at 6 months versus half of that for patients treated with the sentinel lymph node procedure plus radiotherapy. It should be noted that IMRT was utilized in 19% of cases, and chemotherapy was utilized in 12% of cases.
This trial clearly demonstrated that in patients with a macrometastasis or disease greater than 2 mm within a groin node, radiotherapy is not a safe alternative to inguinal femoral lymphadenectomy due to a higher rate of groin recurrence, albeit there was no difference in disease-specific survival.
Management of patients with vulvar cancer is complex. Clinicians need to control the ipsilateral and the contralateral groin. The GROINSS-V II study gives us data on contralateral groin failures also. Overall, there was a very low rate of contralateral groin failure.
The subsequent study GROINSS-V III will evaluate patients with macrometastases and compare inguinal femoral lymphadenectomy versus chemoradiotherapy with weekly cisplatin and an elevated dose of radiotherapy to the groin with 56 Gy utilizing a simultaneous integrated boost technique. It will be quite interesting in years to come to discern if IMRT with more precise daily imaging and dose escalation together with chemotherapy will improve local regional control. Additionally, there may be select populations of node positive patients where intensification of chemotherapy, radiotherapy, or more extensive surgery may be useful. McAlpine and colleagues have demonstrated that cases of HPV-negative vulvar cancers had a markedly inferior survival rate with a hazard ratio of 0.35. It is also hoped that advance radiotherapy techniques such as IMRT will decrease longstanding morbidity such as lymphedema. The GOG prospective study 244 demonstrated no increase in lymphedema in gynecologic cancer patients where radiotherapy was added compared to surgery alone.
The study by Oonk et al. is a remarkable effort in a rare disease demonstrating that patients with micromets can be safely treated with 50 Gy and patients with macromets should be treated with an inguinal femoral lymphadenectomy. It will be very interesting to see if chemoradiotherapy with increased dose can improve local-regional control and provide a high quality of life for patients with macro mets in the GROINS VIII trial.
This concludes this JCO Podcast. Thank you for listening.