Modern External Beam Radiotherapy Techniques for Endometrial Cancer

Endometrial cancer is one of the most common gynecological cancers in the world. The standard treatment of endometrial cancer includes hysterectomy with bilateral salpingooophorectomy, pelvic and/or para-aortic lymph node dissection/sampling, and/or adjuvant radiotherapy [1]. Selection of adjuvant therapy is based on an approximation of the risk of recurrence with features such as stage, tumor histology, lymphovascular space invasion, and patient age. Randomized trials indicated that whole pelvic radiation therapy (WPRT) reduced the rate of pelvic disease recurrence in patients who undergone hysterectomy for endometrial cancer with high risk of recurrence. Radiotherapy is generally administered as external irradiation alone and/or vaginal brachytherapy. The delivery technique is a critical part of the success of radiotherapy for patients with endometrial cancer. Careful consideration of the related factors involved and critical assessment of the techniques available are fundamental to good and effective practice. The purpose of this chapter is to review the modern external beam radiotherapy techniques available for endometrial cancer, including 3D-CRT (Three-dimensional Conformal Radiation Therapy), IMRT (Intensity-modulated Radiation Therapy), HT (Helical Tomotherapy) and VMAT (Volumetric Modulated Arc Therapy), in terms of their physics and technical characteristics, dosimetric advantage, planning and delivery efficiency, taking into account recent advances in this field. A novel conformal arc radiotherapy technique for postoperative WPRT of endometrial cancer will be proposed. The effect of intravenous contrast agent on dose distribution in treatment planning for postoperative WPRT of gynecologic cancer will also be discussed. In addition, the significance of selecting beam energy for the radiotherapy of endometrial cancer will also be covered. Finally, the clinical choice of different techniques will be discussed.