Proton beam therapy for localized prostate cancer 101: basics, controversies, and facts

Abstract

Proton beam therapy for prostate cancer has become a source of controversy in the urologic community, and the rapid dissemination and marketing of this technology has led to many patients inquiring about this therapy. Yet the complexity of the technology, the cost, and the conflicting messages in the literature have left many urologists ill equipped to counsel their patients regarding this option. This article reviews the basic science of the proton beam, examines the reasons for both the hype and the controversy surrounding this therapy, and, most importantly, examines the literature so that every urologist is able to comfortably discuss this option with inquiring patients.

Keywords: External beam radiation therapy; Intensity modulated radiation therapy; Prostate cancer; Proton beam therapy.

Figures

Figure 1

Dose distribution curves of photon and proton beams. The spread-out Bragg peak is demonstrated here to cover the entire target with the maximal dosage.

Figure 2

Schematic of multileaf collimator. Individually positioned tungsten leaflets conform the shape of the beam to the target as used in three-dimensional conformal radiation therapy.

Figure 3

Pencil beam scanning. The pencil beam is swept in a raster pattern back and forth across a target. Reproduced with permission from Mayo Clinic News Network.

Figure 4

Dosimetry plans of various techniques. Radiation dosage across various tissues compared among (A) IMRT, (B) PBT, and (C) IMPT. IMPT, intensity-modulated proton beam therapy; IMRT, intensity-modulated radiation therapy; PBT, proton beam therapy. Reproduced with permission from Trofimov A et al, Int J Radiat Oncol Biol Phys. 2007;69:444–453.