Delaying surgery after neoadjuvant chemoradiotherapy in rectal cancer has no influence in surgical approach or short-term clinical outcomes.

Aims: In rectal cancer, increasing the interval between the end of neoadjuvant chemoradiotherapy (CRT) and surgery could improve the pathological complete response (pCR) rates, allow full-dose neoadjuvant chemotherapy, and select patients with a clinical complete response (cCR) for inclusion in a "watch & wait" program (W&W). However, controversy arises from waiting more than 8-12 weeks after CRT, as it might increase fibrosis around the total mesorectal excision (TME) plane potentially leading to technical difficulties and higher surgical morbidity. This study evaluates the type of surgical approach and short term post-operative outcomes in patients with rectal cancer that were operated before and after 12 weeks post CRT.

Methods: Patients from three centres (two in the UK, one in Portugal) who received rectal cancer surgery following neoadjuvant CRT between 2007 and 2016 were identified from prospectively maintained databases. Preoperative CRT was given to patients with high risk for local recurrence (threatened CRM ≤2 mm or T4 in staging MRI). The baseline characteristics and surgical outcomes of patients that were operated <12 weeks and ≥12 weeks after finishing CRT were analysed.

Results: A total of 470 patients received rectal cancer surgery, of those 124 (26%) received neoadjuvant CRT. Seventy-six patients (61%) were operated ≥12 weeks after end of neoadjuvant-CRT and 48 < 12 weeks. Patients in the ≥12 weeks cohort had a higher BMI (27 vs 25, p = 0.030) and lower lymph node yield (11 vs 14, p = 0.001). The remaining of the baseline characteristics were similar between the two groups (age, operating surgeon, gender, ASA grade, T stage, surgical approach, operation). Operation time, blood loss, conversion rate, length of stay, 30-day readmission rate, 30-day reoperation rate, anastomotic leak rate, 30-day mortality, CRM clearance, and ypT0 rates were similar between the two groups. Univariate and multivariate analysis showed that delaying surgery ≥12 weeks did not affect morbidity and mortality.

Conclusion: In our cohort, there was no difference in short term surgical outcomes between patients operated before or after 12 weeks following CRT. The type of surgical procedures and the proposed approach did not differ due to waiting after CRT. Delaying surgery by ≥ 12 weeks is safe, feasible and does not result in higher surgical morbidity.