The Role of Modern Radiotherapy Technology in the Treatment of Esophageal Cancer

ABSTRACT

Radiation therapy (RT) has improved patient outcomes, but treatment-related complicationrates remain high. In the conventional 2-dimensional and 3-dimensional conformalRT (3D-CRT) era, there was little room for toxicity reduction because of the need to balancethe estimated toxicity to organs at risk (OARs), derived from dose-volume histogramdata for organs including the lung, heart, spinal cord, and liver, with the planning targetvolume (PTV) dose. Intensity-modulated RT (IMRT) is an advanced form of conformal RTthat utilizes computer-controlled linear accelerators to deliver precise radiation doses tothe PTV. The dosimetric advantages of IMRT enable better sparing of normal tissues andOARs than is possible with 3D-CRT. A major breakthrough in the treatment of esophagealcancer (EC), whether early or locally advanced, is the use of proton beam therapy (PBT).Protons deposit their highest dose of radiation at the tumor, while leaving none behind;the resulting effective dose reduction to healthy tissues and OARs considerably reducesacute and delayed RT-related toxicity. In recent studies, PBT has been found to alleviatesevere lymphopenia resulting from combined chemo-radiation, opening up the possibilityof reducing immune suppression, which might be associated with a poor prognosis incases of locally advanced EC.