Low rectal cancer treatment strategies: a cohort study assessing watch and wait.

Purpose: Treatment strategies for low rectal cancer have been evolving toward achieving less treatment morbidity with the same oncological success-we aimed to assess the results of the new watch and wait (W&W) strategy in our cohort.

Methods: A tertiary care cohort study was conducted. New patients with rectal adenocarcinoma up to 6 cm from the anal margin, cM0, locally staged higher than cT1N0, evaluated between November 2014 and October 2018, were included. All 93 patients received neoadjuvant radiotherapy ± chemotherapy. Re-evaluation was planned 8-12 weeks after the end of treatment. Patients showing clinical complete response (cCR) were given the choice of either to proceed to surgery or to enter W&W.

Results: Of the 93 patients, 82.8% were re-evaluated and 20.8% had cCR. Patients in clinical stages II/III were significantly less likely to achieve cCR than those in stage I (p = 0.017). After a mean follow-up of 17.44 months, there were 4 regrowths in the 16 patients under W&W, all submitted to R0 surgery, ypN0; there were no deaths or local recurrences; one patient with regrowth had distant recurrence. Sixty patients underwent direct surgery after a mean follow-up of 16.23 months; 3 patients had local and distant recurrences; 7 others had only distant recurrences; there were 8 deaths. There were no statistically significant differences between patients under W&W and patients who underwent direct surgery regarding local or distant recurrences, or death (p > 0.9; p =  0.44; p =  0.19, respectively).

Conclusion: The W&W strategy for low rectal cancer achieved the same oncological outcomes as the traditional strategy while sparing some patients from surgery.