Neoadjuvant radiotherapy

Over the last two decades, radiation treatment has evolved significantly, not only through its application in serial randomized clinical trials but in many other aspects. One of these key factors is modern imaging, such as computerized tomography and magnetic resonance imaging (MRI), which has become an essential component in determining treatment strategies. In the era of total mesorectal excision surgery (TME), preoperative radiotherapy (RT) reduces local recurrence and can be given either with long-course RT with 5-fluorouracil (5-FU)-based regimen or short-course RT (SCRT). For patients with positive circumferential radial margin (CRM), tumor down-staging is highly desirable, and SCRT is not as effective to prevent local recurrence. Contemporary pattern of recurrence suggests that it is possible to lower the upper limit of the treatment field level. In an effort to reduce radiation-related toxicity, field adjustments along with exploration of new radiation targeted radiation modalities are desirable.