Upfront Boost Followed by Elective Node Radiation [UBER] for Treatment of Locally Advanced Cancer of the Vulva in Older (> 70 years) Women

Abstract

<h3>Purpose/Objective(s)</h3> Three key radiation metrics identified for optimizing treatment of cancer (ca) of the vulva include: completion of ≥ 20 fractions, overall treatment duration of < 8 weeks (56 days), and <1 week treatment break. Among older women (≥ 66 years) compliance to all 3 metrics is noted only 50% of the time.¹ Our study aims to evaluate treatment metrics of a radiation sequence that delivers upfront boost to the primary and positive inguinal nodes followed by adding a pelvic field for elective regional node radiation [UBER]. We reasoned that by initially targeting the highest risk volume of disease, and delaying the onset of acute (gastrointestinal, hematologic) toxicity generally associated with pelvic field radiation we may observe better compliance to RT delivery metrics in older women. <h3>Materials/Methods</h3> From September 2019 to October 2021, we identified 5 patients over the age of 70 years diagnosed with ca of the vulva and treated with radiation using the UBER sequence. All 5 patients had locally advanced clinical stage (cT3/T4 and/or node positive). Three patients received primary RT+ weekly cisplatin, 1 patient each received primary RT, and adjuvant RT alone. The RT dose/ fractionation prescribed was at the discretion of the treating physician, and 4/5 patients were treated using IMRT plans. <h3>Results</h3> The median age is 79 years [73-88 years]. The upfront boost dose delivered to the primary and positive inguinal nodes ranged from 900cGy to 2400cGy. The larger pelvic field including the primary, inguinal and pelvic nodes received a dose that ranged from 3420cGy to 4500cGy. The composite RT dose/ fractions ranged from 4320cGy/ 24 fractions to 6480cGy/36 fractions delivered over an average of 54 elapsed days [range: 37 to 69 days]. The average treatment break was 4 days [range: 0 to 6 days]. Two of the 3 patients received all 6 cycles of concomitant weekly cisplatin, and 1/3 patients received 5 cycles. Patient status at median follow up of 6 months (range: 3 to 22 months) is: 2 alive with no evidence of disease, 1 alive with partial response, 1 alive with disease progression, and 1 died of disease. <h3>Conclusion</h3> Early experience with the UBER sequence suggests high compliance to clinically important RT delivery metrics i.e., completion of > 20 fractions, average overall treatment time of < 8 weeks with < 1 week treatment break. Additionally, patients were able to receive 5-6 cycles of concomitant weekly cisplatin. In a particularly challenging older patient population with ca of the vulva further study of the UBER sequence is warranted. ¹ Swanick CW et al: Gynecol Oncol 146:87, 2017