Local excision after (near) complete response of rectal cancer to neoadjuvant radiation: does it add value?

Neoadjuvant radiotherapy is commonly used in rectal cancer. When used prior to radical surgery in locally advanced disease, up to one-quarter of patients have no residual cancer at surgery suggesting that radical surgery was unnecessary; those with complete clinical response may be managed on a rectal-preserving 'watch-and-wait' pathway. In those receiving radiotherapy for early stage cancer, local excision of small volume residual or recurrent tumour is possible, but its value is unclear.

Data were collected from two institutions (UK and Denmark) which maintain prospective databases on all patients undergoing local excision by transanal endoscopic microsurgery (TEM). The study group was all patients who had TEM after neoadjuvant radiation for rectal cancer over an 11-year period.

Forty-five patients had TEM after neoadjuvant radiation, 18 after short course radiotherapy (SCRT) and 27 after chemoradiotherapy (CRT). Local recurrence occurred in 13 (29%) and distant metastases in 11 (24%). Complete pathological response was noted in 10 (22%), 28% after SCRT and 19% after CRT, p = 0.02. However, local recurrence still occurred in 60% of those with ypT0 after SCRT. The recurrence rate may be higher in those with residual disease at TEM compared with complete responders (40 vs 30%).

If complete response can be determined clinically, local excision of the scar does not confer benefit, but follow-up should be maintained. If there is regrowth or residual tumour at TEM, further recurrence is common, and the benefits of TEM may not outweigh the risks, except in those unsuitable for radical surgery.