Response prediction in the multimodality therapy of locally advanced rectal cancer

Neoadjuvant therapies have been established in the multimodality treatment of locally advanced rectal cancer. Radiation with concurrent 5-fluorouracil-based chemotherapy followed by surgical resection is considered to be the standard of care in advanced rectal cancer. However, recent studies revealed that patients with complete histopathologic response seem to benefit most from neoadjuvant therapies. Consequently, predictive markers to allow individualization of multimodality therapy in locally advanced rectal cancer are mostly required to identify those who will benefit the most. Unfortunately, there is still an immense lack of factors for response assessment in patients with rectal cancer undergoing multimodality treatment. While conventional diagnostic tools lack sufficient accuracy to provide information for response assessment, newer techniques such as [F-18]-fluorodeoxyglucose-PET and diffusion-weighted MRI show promising results. In addition, studies on molecular factors for response assessment in rectal cancer are encouraging but still do not provide a reliable instrument for utilization in clinical practice.