Intensity-Modulated Proton Beam Therapy of Prostate Cancer-History, Results, and Future Directions

Abstract

Proton beam radiation therapy is a form of external—beam radiation treatment which takes advantage of the superior physical properties of positively charged subatomic particles (i.e., low entrance dose and lack of exit dose) to deliver highly conformal radiation therapy with a lower integral dose (dose to normal tissue) than can be achieved with photon-based treatments. Proton beam radiation therapy first became available on an extremely limited basis in the late 1950s, and was initially used to treat prostate cancer in the late 1970s. More recently, intensity—modulated proton therapy (IMPT), in which all beam shaping and modulation is performed electromagnetically, has become available at a number of proton centers. This improvement in proton beam treatment delivery significantly expands the utility of proton therapy by allowing for treatment of complex target volumes such as the whole pelvis and by permitting the creation of highly individualized nonuniform dose distributions, including the use of simultaneous integrated boosting. This chapter will review the history of proton beam therapy of prostate cancer, beginning with the initial patient treatments at the Harvard Cyclotron Laboratory and continuing up to the present day, with particular emphasis being placed upon emerging trends in proton beam treatment technology and their potential impact on the future of proton beam therapy in prostate cancer.