Occult adenocarcinoma in adenomas. Possibilities of diagnostic methods

Aim: to analyze the diagnostic value of the digital rectal examination, colonoscopy, MRI and ERUS for detecting occult adenocarcinoma in rectal adenomas.

Patients and methods: the study included 100 patients with newly identified epithelial rectal neoplasms, which undergone transanal endoscopic microsurgery from December 2019 to December 2020. All the patients underwent digital rectal examination, colonoscopy, ERUS with sonoelastography, and pelvic MRI. The diagnostics value of this methods was estimated with determination of sensitivity and specificity.

Results: the study included 67 (67%) females and 33 (33%) males. The mean age of the patients was 64.4 ± 10.7 years. The median distance from the tumor to the anal verge was 6.0 ± 2.9 cm. The sensitivity of the digital rectal examination in the occult malignancy verification was 0.44 (95% CI 0.24–0.65), specificity — 0.93 (95% CI 0.85–0.97). The sensitivity of the colonoscopy — 0.56 (95% CI 0.34–0.75), the specificity — 0.84 (95% CI 0.73–0.91). The sensitivity of MRI — 0.40 (95% CI 0.21–0.61), specificity — 0.89 (95% CI 0.80–0.95). The sensitivity of ERUS was 0.48 (95% CI 0.27–0.68), the specificity — 0.73 (95% CI 0.61–0.82). Pair wise comparison of diagnostic methods revealed the absence of significant differences in their diagnostic value (p > 0.05).

Conclusion: at least one of diagnostic methods allows to verify the presence of malignant transformation in 100% of cases. So, only combination of diagnostic methods can help to choose the optimal treatment option.

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