Predictors of response in locally advanced rectal cancer following concurrent chemoradiotherapy

Colorectal cancer (CRC) is one of the most common malignancies and the third major cause of cancer-related deaths in Taiwan. In 2011, more than 13,000 new cases of CRC were diagnosed and more than 4921 Taiwanese died from CRC. Standards of rectal cancer diagnosis and treatment have changed considerably during the past decade. Although surgery is still considered the cornerstone of rectal cancer treatment, high rates of local recurrence and unsatisfactory survival rates (40–55% at 5 years) have remained significant problems, even in patients subjected to curative resection. Preoperative chemoradiotherapy (CRT) is currently considered the standard treatment for locally advanced rectal cancer, and oncological outcomes using this approach are encouraging, with rates of local and distant recurrence at the five-year mark being 6–9% and 33–36%, respectively. The peculiar aspects of this approach are related to clinical over-staging, which may result in unnecessary neoadjuvant treatment in almost 18–20% of cases as proven in a trial conducted in Germany. This article focuses on the results of studies assessing the predictors of responses for locally advanced rectal cancer patients following CRT. The ability to predict response to preoperative CRT can prevent unnecessary treatment and protect poorly responding patients from the side effects of neoadjuvant treatment.