{'fraction_non_alphanumeric': 0.05220633934120572, 'fraction_numerical': 0.032939714108141706, 'mean_word_length': 5.0299625468164795, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Fourth versus eighth week surgery after neoadjuvant radiochemotherapy in T3-4/N0+ rectal cancer: Istanbul R-01 study.

BACKGROUND AND PURPOSE
The optimum duration between neoadjuvant radiochemotherapy and transmesorectal excision in locally advanced rectal cancer has not been defined yet. This randomized study was designed to compare the efficacy of four-week versus eight-week delay before surgery.


METHODS
One-hundred and fifty-three patients with locally advanced low- or mid-rectum rectal adenocarcinoma were included in this single center prospective randomized trial. Patients were assigned to receive surgical treatment after either four weeks or eight weeks of delay after chemoradiotherapy. Patients were followed for local recurrence and survival, and surgical specimens were examined for pathological staging and circumferential margin positivity.


RESULTS
4-week and 8-week groups did not differ with regard to lateral surgical margin positivity (9.2% vs. 5.1%, P=0.33, respectively), pathological tumor regression rate (P=0.90), overall survival (5-year, 76.5% vs. 74.2%, P=0.60) and local recurrence rate (11.8% vs. 10.3%, 0.77). Overall survival was better in patients with negative surgical margins (78.8% vs. 53.0%, P=0.04). Local recurrence rate was significantly higher among patients with positive surgical margin (28.5% vs. 9.3%, P=0.02).


CONCLUSIONS
Intentional prolongation of the chemoradiotherapy-surgery interval does not seem to improve clinical outcomes of patients with locally advanced rectal cancer. Surgical margin positivity seems to be more important with this regard.