Is “watch-and-wait” after chemoradiotherapy safe in patients with rectal cancer?

### What you need to know Colorectal cancer is the third commonest cancer worldwide.1 About a third of these arise in the rectum. Approximately a third of rectal cancers are locally advanced and at high risk of recurrence. Long-course chemoradiotherapy followed by surgical resection is now standard treatment for these tumours in the UK,23 Europe,4 the US,5 and Australia.6 However, surgery is associated with major complications (up to 15%), perioperative mortality (up to 5%), and the need for a permanent stoma in up to a quarter of patients.7 Within the published literature, after chemoradiotherapy 10-25% of patients have no residual tumour on pathological examination after surgical resection.78910 Clinical examination before surgery in these patients has shown an equivalent favourable response, referred to as a clinical complete response. The criteria for defining a clinical complete response include absence of residual ulceration, stenosis, or mass within the rectum during digital rectal examination and endoscopic examination (fig 1).910 Fig 1 Endoscopic images of rectum after chemoradiotherapy for rectal cancer show (A) “white” scar (circled) and (B) telangiectasia changes (arrow). Both are accepted as “normal” and are compatible with a clinical complete response Nearly 15 years ago, a seminal study from a centre in Sao Paulo, Brazil reported that 71 patients with clinical complete response were managed without initial surgery. Instead they were managed by a non-surgical “watch-and-wait” …