Aim: to assess the effectiveness of neo-CT in the FOLFOX6 regimen in patients with mid- and upper rectal cancer (RC)associated with poor prognosis.   Patients and methods: fifty-two patients were included into study. All had neo-CT with subsequent surgical treat-ment between 2017 and 2021. Of them 94.2% had stage III and 5.8% had stage II. An extramural vascular invasionwas detected by MRI in 33 (63.5%) patients. The distance between the tumor and the mesorectal fascia was ≤ 2 mmin 17%. All patients had 4 cycles of neo-CT in FOLFOX6 regimen followed by surgery.   Results: the compliance (≥ 4 cycles of neo-CT) was 82.7 % (n = 43). The overall toxicity rate was 35.6 %. Sphincter-saving surgery was performed in 51 (98.1 %) patients. Postoperative morbidity was 25.0 %. Final pathology revealed stage III in 29 (55.8 %) patients, stage 0 — stage II — in 22 (42.3 %). In accordance with the degree of pathomorphosis (CAP, 2019), 12 (23.1 %) patients showed a partial response. In one patient (1.9 %) no signs of residual tumor were detected. Downstaging of the T stage compared with MRI data before neo-CT was noted in 23 (44.2 %) patients, N stage — in 29 (55.8 %). With a mean follow-up of 31 (3-54) months, local recurrences were detected in 5 (9.6 %) patients, and distant metastases in 4 (7.7 %). The cumulative 3-year recurrence rate was 11.3 ± 4.8 %. The three-year overall and recurrence-free survival rate was 88.2 ± 5.8 % and 76.4 ± 7.4 %, respectively.   Conclusion: the multimodal approach for RC with adverse prognostic factors using neo-CT in the FOLFOX6 regimenis well tolerated by patients, has a small toxicity and postoperative morbidity as well. It is necessary to develop newpathology criteria for tumor response to neo-CT.

The article presents a clinical case of using the active follow-up strategy (the so-called watch wait) in a 73-year-old patient with cancer of the lower rectum with a good response to neoadjuvant chemoradiation therapy (NCRT). After 3 years of regular follow-up, including digital rectal examination, rectoscopy and MRI, indicating the absence of tumor progression, PET / CT with 18F-FDG was obtained, which revealed a region of hypermetabolic activity in the lower rectum (SUVmax = 27.1), in connection with which it was decided to carry out surgical treatment.When discussing the issue of the volume of the operation, MRI data were taken into account, supplemented by the results of T2-weighted texture analysis, which confirmed the absence of progression. The patient underwent organ-preserving treatment in the amount of transanal tumor resection. Pathomorphological examination after surgery established the inflammatory changes in the intestinal wall and absence of tumor. This case demonstrates the effectiveness of the standard examination volume when using the watch wait strategy and the possibility of using T2-WI texture analysis to increase the reliability of MRI assessment of tumor response to chemotherapy.

In the literature review, the problem of colorectal anastomosis leakage is considered with an emphasis on the role and capabilities of radiology, including methodological features, diagnostic effectiveness and characteristic manifestations at various times after surgery, also controversial and unresolved issues of the use of various methods of radiation research are noted.