Neoadjuvant treatment of rectal cancer: Where we are and where we are going

Abstract

Locally advanced rectal cancer requires a multidisciplinary approach based on total neoadjuvant treatment with radiotherapy (RT) and chemotherapy (ChT), followed by deferred surgery. Currently, alternatives to the standard total neoadjuvant therapy (TNT) are being explored, such as new ChT regimens or the introduction of immunotherapy. With standard TNT, up to a third of patients may achieve a complete pathological response (CPR), potentially avoiding surgery. However, as of now, we lack predictive markers of response that would allow us to define criteria for a conservative organ strategy. The presence of mutations, genes, or new imaging tests is helping to define these criteria. An example of this is the diffusion coefficient in the diffusion-weighted sequence of magnetic resonance imaging and the integration of this imaging technique into RT treatment. This allows for the monitoring of the evolution of this coefficient over successive RT sessions, helping to determine which patients will achieve CPR or those who may require intensification of neoadjuvant therapy.

Keywords: Locally advanced rectal cancer, Total neoadyuvant treatment, Radiotherapy, Biomarker, Magnetic resonance imaging, Conservative organ strategy, Watch and wait

Core Tip: The treatment of rectal cancer is well-established, based on total neoadjuvant treatment followed by deferred surgery. However, the development of biomarkers is necessary to predict which patients will achieve a complete pathological response and, therefore, may not require surgical treatment. The advent of new imaging techniques and their morphological, metabolic, and functional information pave the way for defining criteria for patients with locally advanced rectal cancer who are candidates for a conservative strategy.