Chi_Principles and Practice of Gynecologic Oncology 8e

Chapter 2.6 ■ Therapy for Vulvar Cancer: Radiation, Systemic Therapy, and Treatment of Persistent and Recurrent Disease 25

❚ Figure 2.6-1. A: Conventional radiotherapy. B: Intensity-modulated radiation therapy in the management of vulvar cancer. (Reprinted with permission from Beriwal S, Heron D, Kim H, et al. Intensity-modulated radiotherapy for the treatment of vulvar carcinoma: a comparative dosimetric study with early clinical outcome. Int J Radiat Oncol Biol Phys . 2006;64:1395-1400.)

possible superimposed Candida infection all help to minimize the discomfort. Although most patients will develop patchy to con fluent dermatitis by the fourth week of treatment, this is usually tolerated if the patient is warned in advance and assured that the discomfort will resolve after treatment is completed. Although a treatment break is occasionally required, delays should be mini mized, because they may allow time for repopulation of tumor cells. IMRT helps reduce dose to uninvolved skin, especially in groin regions, which reduces dermatitis (73). Late Complications of Radiation Therapy Many factors contribute to the late morbidity of RT in patients with vulvar carcinoma. Patients with advanced vulvar carcinomas are often treated with RT following radical surgery, which may include extensive dissection of the inguinal and possibly pelvic nodes. Lymphedema is a chronic, disabling condition that occurs in more than 40% of patients after groin dissection as reported in the prospective GOG 244 study (78). The incidence of lower ex tremity edema after inguinal irradiation alone appears to be small (46). RT is likely to contribute to the cumulative incidence of pe ripheral leg edema following radical node dissection, but there was no significant difference evident in the GOG 37 randomized study of radiation (16%) versus pelvic node dissection (22%) (53). Other complications include the risk of pelvic and femoral head fracture, most notably when delivering RT to the inguinal nodes (79,80). Older techniques provided substantial dose to the fem oral heads, which can be decreased by techniques such as IMRT (73,81). IMRT technique has also been associated with decreased long-term bowel and bladder toxicity (74,75). The effect of RT on the long-term cosmesis and function of the vulva is poorly understood. Although treatment with radiation or CRT and wide excision is becoming a more accepted alternative to extensive surgery for selected patients, and major complication rates appear to be acceptable, very little has been reported regard ing subtler late effects of such treatment in the vulva. Possible late effects include atrophy and telangiectasias. Late effects are ex pected to be dose related. Better information will become available only as treating physicians record and report the late cosmetic and functional results of treatment (82). Pelvic RT is associated with late vaginal toxicity such as vaginal stenosis, which may be pre vented with use of a vaginal dilator (83).

decreasing radiation dose to nearby healthy normal tissue, im proving the therapeutic window for radiation. Although outcome data on IMRT for vulvar cancer remain limited to mainly single-­ institution series (51,52), the adoption of IMRT has been spurred by experience extrapolated from the treatment of anal carcinoma (73) and other gynecologic cancers in multi-institutional clinical trials (74,75). Prospective studies randomizing patients with cervical and endometrial cancer to postoperative pelvic RT using IMRT versus 3D technique have shown decreased acute bowel toxicity, improved patient-reported bowel quality of life, as well as decrease in both late bowel and bladder toxicities with IMRT (74,75). IMRT is also asso ciated with improved bone marrow sparing, leading to less acute hematologic toxicity (76) and pelvic insufficiency fractures (77). Conventional (Two- and Three-Dimensional) Radiotherapy Historically, conventional RT approaches were based on bony anatomy as opposed to CT-based planning using anatomically de fined targets. The typical plan utilized an anterior field that encom passed the inguinal regions, lower pelvic nodes, and vulva and a narrower posterior field that encompassed the lower pelvic nodes and vulva but excluded most of the femoral heads. The intent was to cover one nodal echelon proximal to the involved nodal echelon. The inferior-most borders of the fields extended 2 to 3 cm caudal to the saphenous and femoral vein junction. If the fields are evenly weighted to the midplane of the pelvis using 6 MV photons, the contribution of the anterior field to the groin nodes at a depth of 3 to 5 cm is generally 60% to 70% of the dose to the mid-pelvis. The difference would be made up by supplementing the dose to the lateral groins with anterior electron fields of appropriate energy. Some practitioners would use 6 MV from the anterior field and 15 MV from the posterior field to spare posterior organs at risk. Gross disease in the groin or vulva was boosted sequentially with en face electron fields or conformal photon RT. Acute Complications of Radiation Therapy Acute radiation skin reactions are brisk, and doses of 35 to 45 Gy routinely induce patchy or confluent moist desquamation. How ever, with adequate local care, this acute reaction usually heals within 3 to 4 weeks. Sitz baths, steroid cream, and treatment of

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