[The importance of radiotherapy in rectal cancer-an update from a surgeon's perspective]

Neoadjuvant chemoradiotherapy was implemented in the treatment of rectal cancer for UICC stages II and III in 2004. Recent studies have provided new insights with respect to the indications and sequence of radiotherapy in the concept of multimodal treatment.

The aim of the study was to review the status of radiotherapy in the context of current developments in the treatment of rectal cancer, such as magnetic resonance imaging (MRI)-based surgery, total neoadjuvant therapy and the watch and wait strategy for complete clinical remission.

The indications for neoadjuvant radiotherapy based on the clinical T and N stages are not exact and can lead to overtreatment in 18-27% of cases. Radiotherapy is associated with a worsening of anorectal and urogenital functions. Local recurrence rates of 3% with surgery alone can be achieved in patients with negative circumferential resection margins (low risk cancer) in MRI. For rectal cancer with high-risk features, such as cT4 tumor, positive circumferential resection margins and extramural vascular invasion, an improved disease-free survival and a lower rate of distant metastases could be achieved with total neoadjuvant therapy compared to standard neoadjuvant chemoradiotherapy in recent phase III randomized trials. Pathological complete remission is achieved in 28% of patients after total neoadjuvant therapy.

The high rate of complete remission has fired the debate regarding watch and wait after total neoadjuvant therapy; however, no prospective randomized phase III trials comparing total mesorectal resection vs. watch and wait in complete clinical remission have been published. Hence, resection remains the gold standard in this scenario given the excellent long-term oncological results.