Morbidity Related to the Use of 3D-Based External Beam Radiation and Image-Guided Brachytherapy

Abstract

Radiation-related side effects, particularly with regard to brachytherapy, are an important potential consequence of the treatment of various cancers. To date, several publications have reported toxicity rates related to standard brachytherapy techniques for cervical cancer. In the era of 3D-guided BT, most centres that have implemented IGABT deliver external beam radiation therapy (EBRT) using 3D-conformal techniques. The issue of organ at risk (OAR) sparing by way of intensity-modulated radiotherapy (IMRT) to the pelvis is still controversial. Moreover, differentiating chemotherapy-related side effects from radiation-related side effects may be challenging. Besides, a number of toxicity grading systems have developed over the years, including the WHO, RTOG/EORTC, LENT-SOMA, French-Italian glossary, and CTC systems. All of these systems incorporate toxicities resulting from the sum of the external beam radiotherapy (EBRT) and the brachytherapy dose. There is some, but not complete, overlap of the grading system, which makes comparison more difficult. The difference between these scoring systems may have consequences for the reporting of late side effects. In addition, physician based quantification of side effects may be perceived and consequently ranked differently by patients. With IGABT, there is a trend toward decreasing dose to OARs and subsequently radiation-related late side effects. Nevertheless, existing data must mature in order to reach definitive conclusions. To date, the literature on the side effects of 3D-conformal EBRT combined with 3D IGBT is very limited. In this chapter we will address both acute and late radiation effects, with a greater focus on late morbidity. Key OARs include the rectum, bladder, sigmoid colon, vagina, and small bowel.