The Norwegian Watch and Wait study: Norwait for rectal cancer. A report from a failed study-a word of caution.

The paucity of prospective data on the subject of Watch and Wait for rectal cancer prompted the implementation of Norwait, a population-based study including rectal cancer patients after neoadjuvant therapy. The aim of the study was to assess the accuracy of clinical complete response (cCR) and quantify the regrowth rates. Norwait was a prospective population-based observational study with ethical approval (2017/935) registered at clinicaltrials.com (NTC03402477). Residents of Norway with histologically proven rectal cancer located within 15 cm from anal verge were eligible following completion of radiotherapy or chemoradiation at seven hospitals. cCR was the disappearance of tumour and of any ulcer with/without the appearance of whitening of prior tumour site and telangiectasia evaluated at 12 weeks by digital rectal exam, and endoscopic imaging. The study aimed to include 100 cCR patients with regrowth rates as primary endpoint. The data are presented in crude form. Eighty-two patients were included in seven hospitals from 2018 to 2020 when the study was terminated. Fifty-one patients were included in six hospitals, whereas protocol violations were identified in one hospital, where thirty-one (rather than protocol-estimated 12) patients were enrolled. Amongst the 31 patients, there were only 2 with documented cCR. Of the latter 29, there were 16 with ulcer or persistent tumour, and 13 without any documentation of cCR. Of these, 23 underwent surgery with a delay up to 50 weeks. At median 54-month follow-up of 31 patients, there were 77% local regrowths (n = 23), 40% metachronous metastases (n = 12) and 23% deaths (n = 7). At median 54-month follow-up of 51 cCR patients, there were 53% local regrowths (n = 27), 14% metachronous metastases (n = 7) and 4% deaths (n = 2). Norwait admonishes a word of caution reaching beyond the inconclusive results of a population-based study jeopardised by serious violation to protocol and legislation for conducting safe research.