Radiation Therapy for Desmoid Tumors

Abstract

Radiation therapy uses high-energy ionizing radiation beams to treat malignant cancers as well as a variety of benign tumors and medical conditions. James Ewing was the first to report the successful use of radiotherapy in the management of unresectable desmoid tumors in 1928 [1]. Since then several studies have shown excellent control rates with radiation, which indicate a role for radiotherapy in the multidisciplinary management of these nonmalignant tumors [2–6]. Currently, radiation can be used as the primary treatment for desmoids, as an adjunct to surgery, and as the treatment of recurrent disease.

Surgery has generally been the standard initial modality for treating patients with desmoid tumors, although experience is accumulating with a more conservative approach of initial observation, deferring surgery or other treatment until there is evidence of progression [7, 8]. Optimizing local control is the key element for the curative treatment of these benign tumors, given their inability to metastasize and the expectation of long-term survival for most patients. This underlies the rationale for combining surgical resection and radiotherapy with the goal of improving local control and to limit the morbidity associated with recurrence in some patients. Despite the large number of published series examining the effect of adding radiation to surgery, there is a lack of consensus on the indications for such an approach. Furthermore, due to the low incidence of desmoids, there are no randomized controlled trials comparing the effect of different treatment modalities in the management of desmoid tumors. In the absence of such high-level evidence, the application of radiation in the management of desmoids is based upon effectiveness seen in retrospective and phase II studies. In most of these studies, radiation has been used largely in patients who have recurred after initial surgery and as primary treatment in those patients who are medically inoperable or those in whom resection presents unacceptable morbidity [9–12]. However, because there are other treatment modalities available for the management of desmoids, the use of radiotherapy must be considered carefully in light of the potential long-term side effects of radiotherapy including the risk of secondary malignancy, particularly in younger patients. Table 8.1 outlines the principles of irradiating nonmalignant diseases, which applies to the use of radiation in this disease [13]. Ultimately, treatment decisions are individualized to each patient depending on a range of patient and tumor characteristics [8, 14]. In Fig. 8.1, we outline a treatment algorithm that we have found useful in managing patients with desmoid tumors.

In this chapter, we discuss separately the role of radiation in the treatment of primary and recurrent desmoid tumors. We will also review the basics of radiation treatment planning and the different radiation techniques that can be applied.