The role of radiation treatment in intermediate risk endometrial cancer-pro

Abstract

The role of adjuvant, post-hysterectomy radiation therapy in patients who have early stage endometrial cancer with high-risk features continues to be a subject of controversy. Findings such as deep myometrial invasion, high grade, large tumor size, lymph-vascular invasion, cervical stromal involvement, and advanced age are all associated with increased risk of locoregional recurrence. Numerous retrospective and several prospective studies have demonstrated that pelvic radiation therapy reduces the risk of recurrence in patients with these findings. However, selection bias makes it impossible to determine the influence of adjuvant treatment from retrospective studies. Several prospective randomized trials have attempted to study the role of adjuvant pelvic radiation in patients with so-called intermediate risk disease. These include recently published trials from PORTEC(1) and the GOG(2) and a much older trial from the Norwegian Radium Hospital(3). Unfortunately, the majority of patients in each of these trials had relatively favorable low-grade or minimally invasive disease. Although all of these trials demonstrated significant reductions in the pelvic recurrence rates with adjuvant radiation, the inclusion of many patients with low-risk disease reduced their power to detect survival differences. Nevertheless, subset analyses suggested that patients who had high intermediate risk factors experienced a benefit from adjuvant radiation therapy with absolute survival differences that could be as great as 15–20% and reductions in the risk of death of as much as 50%. Although it has been suggested that post-hysterectomy pelvic recurrences (most of which involve the vaginal apex) can be easily salvaged, data suggest that 5-year survival rates for patients with vaginal recurrence are ≤40%, particularly for patients with high-grade lesions(4). Intracavity irradiation may reduce the risk of recurrence in the vagina but the Norwegian trial(3) suggests that pelvic RT may be more effective. In the absence of trials adequately addressing the benefit of radiation in patients with high-intermediate risk disease, treatment must be individualized after careful consideration of its potential risks and benefits.