The variation of inguinal lymph node depth in adult women and its importance in planning elective irradiation for vulvar cancer

Abstract

The Gynecologic Oncology Group (GOG) protocol #88 reported an 18.5% failure in inguinal lymph nodes of patients with vulvar cancer whose groins were treated with radiation alone. This high failure rate may be due to the study design. In this study, the depths of inguinal lymph nodes were evaluated with computed tomography (CT) scans in 100 adult women without inguinal adenopathy or prior inguinal surgery. The dose that would have been delivered to the inguinal lymph nodes of these patients was determined using isodose curves constructed according to the guidelines in GOG protocol #88. Only 18% of women had all inguinal lymph nodes measured at a depth of 3 cm or less. More than one-half of all women in this study would have received less than 60% of the prescribed radiation dose because their inguinal lymph nodes were deeper than 5 cm, if the depth of their inguinal lymph nodes had not been measured before therapy.