Intensity-Modulated Radiation Therapy in Gynecologic Cancers: Growing Support, Growing Acceptance

Abstract

Since the initial report on treatment of gynecologic cancer patients with intensity-modulated radiation therapy (IMRT),1 enthusiasm for its use has steadily grown. In 2002, we performed a nationwide survey and found that 15% of IMRT users had treated at least one gynecologic patient with IMRT. 2 In our 2004 follow-up survey, this percentage had increased to 35%, making gynecology the fourth most common site treated with IMRT and the most rapidly growing IMRT site overall. 3 Given the strong motivation for the use of IMRT in gynecology patients, such enthusiasm is understandable. Conventional fields irradiate large volumes of normal tissue, including bowel, bladder, rectum, bone marrow, and femoral heads, exposing women to a wide variety of acute and late sequelae. Concerns about toxicity also limit the total radiation dose prescribed, despite potential benefits of dose escalation in women with gross residual or unresectable disease. Finally, although brachytherapy is a cornerstone of gynecologic radiotherapy, it is not feasible or optimal in all patients, and IMRT may represent a viable alternative to, or replacement for, brachytherapy. Despite these rationales, concerns exist regarding the widespread use of IMRT in gynecology patients. One relevant concern is that although many studies demonstrate the superiority of IMRT planning over conventional techniques, published outcome studies of treated patients are still sparse. Moreover, the few existing clinical studies still have short follow-up and limited information on long-term toxicities. In this issue of The Cancer Journal, Chen and colleagues4 provide important new evidence again suggesting clinical benefits of IMRT in gynecology patients. These investigators report their institutional experience with IMRT in a relatively large cohort of postoperative cervical cancer patients. Patients in this study had high-risk features after surgery and underwent adjuvant pelvic IMRT with concurrent chemotherapy and brachytherapy. IMRT plans were highly conformal, resulting in excellent target coverage and sparing of surrounding normal tissues. IMRT was well tolerated in all patients, with minimal acute genitourinary and gastrointestinal toxicity. More importantly, however, these women had an excellent long-term pelvic control (3-year locoregional control, 93%) and a low incidence of severe late toxicity (1 grade 3 genitourinary and no grade 3 gastrointestinal toxicity). This study represents an important contribution to the gynecologic IMRT literature and, together with other recent reports focusing on tumor control and long-term toxicity, 5,6 provides further evidence that improved dosimetry of IMRT translates into clinically significant benefits.