The MRI assessment of SPECC (significant polyps and early colorectal cancer) lesions

Endoscopic intermuscular dissection for deep submucosal invasive cancer in the rectum: a new endoscopic approach

BACKGROUND

The risk of lymph node metastasis associated with deep submucosal invasion should be balanced against the mortality and morbidity of total mesorectal excision (TME). Dissection through the submucosa hinders radical deep resection, and full-thickness resection may influence the outcome of completion TME. Endoscopic intermuscular dissection (EID) in between the circular and longitudinal part of the muscularis propria could potentially provide an R0 resection while leaving the rectal wall intact.

METHODS

In this prospective cohort study, the data of patients treated with EID for suspected deep submucosal invasive rectal cancer between 2018 and 2020 were analyzed. Study outcomes were the percentages of technical success, R0 resection, curative resection, and adverse events.

RESULTS

67 patients (median age 67 years; 73 % men) were included. The median lesion size was 25 mm (interquartile range 20-33 mm). The rates of overall technical success, R0 resection, and curative resection were 96 % (95 %CI 89 %-99 %), 81 % (95 %CI 70 %-89 %), and 45 % (95 %CI 33 %-57 %). Only minor adverse events occurred in eight patients (12 %).

CONCLUSION

EID for deep invasive T1 rectal cancer appears to be feasible and safe, and the high R0 resection rate creates the potential of rectal preserving therapy in 45 % of patients.

MDT stage migration in MRI of significant rectal polyps and early rectal cancers

PURPOSE

To audit the diagnostic accuracy of MRI for staging early and polyp rectal cancers with the purpose of identifying scope for service improvement.

METHODS

This is an IRB approved retrospective study of patients who underwent staging MRI for rectal growths followed by upfront TME type surgery or local excision without neoadjuvant therapy between 2018 and 2021. MR-T-stage was compared with surgical histopathology. The degree of stage migration in the multidisciplinary team meetings (MDT) was assessed and training needs were identified.

RESULTS

53 patients (32 males) with a mean (SD) age of 56.7 (13.6) years with 54 rectal lesions and underwent trans-anal excision (n = 18) or upfront surgery (n = 35) were included. Pathology showed < / = pT1 stage in n = 18 and > / = pT2 stage in n = 36. Radio-pathological concordance rate was 38.9% and 74.1%, respectively, for primary reports and MDT reads, respectively, and during MDT, the rates improved by 44.5% and 30.5% for < / = pT1 and > / = pT2 stages ,respectively. The overall T-stage migration rate at MDT was 44.6% (25/54) and the migration rate was higher (61.1%) for < / = pT1 stage lesions. The best sensitivity, specificity, PPV, NPV and accuracy of MRI for T-staging was 83.3%, 91.6%, 83.3%, 91.6% and 88.8%, respectively.

CONCLUSION

Radio-pathological correlation for MRI T-stage is excellent for MDT reads by experienced radiologists. MDT reads lead to significant down-staging of T-stage in polyp and early rectal cancer thereby improving radio-path correlation.

Current and future role of three-dimensional modelling technology in rectal cancer surgery: A systematic review

BACKGROUND

Three-dimensional (3D) modelling technology translates the patient-specific anatomical information derived from two-dimensional radiological images into virtual or physical 3D models, which more closely resemble the complex environment encountered during surgery. It has been successfully applied to surgical planning and navigation, as well as surgical training and patient education in several surgical specialties, but its uptake lags behind in colorectal surgery. Rectal cancer surgery poses specific challenges due to the complex anatomy of the pelvis, which is difficult to comprehend and visualise.

AIM

To review the current and emerging applications of the 3D models, both virtual and physical, in rectal cancer surgery.

METHODS

Medline/PubMed, Embase and Scopus databases were searched using the keywords “rectal surgery”, “colorectal surgery”, “three-dimensional”, “3D”, “modelling”, “3D printing”, “surgical planning”, “surgical navigation”, “surgical education”, “patient education” to identify the eligible full-text studies published in English between 2001 and 2020. Reference list from each article was manually reviewed to identify additional relevant papers. The conference abstracts, animal and cadaveric studies and studies describing 3D pelvimetry or radiotherapy planning were excluded. Data were extracted from the retrieved manuscripts and summarised in a descriptive way. The manuscript was prepared and revised in accordance with PRISMA 2009 checklist.

RESULTS

Sixteen studies, including 9 feasibility studies, were included in the systematic review. The studies were classified into four categories: feasibility of the use of 3D modelling technology in rectal cancer surgery, preoperative planning and intraoperative navigation, surgical education and surgical device design. Thirteen studies used virtual models, one 3D printed model and 2 both types of models. The construction of virtual and physical models depicting the normal pelvic anatomy and rectal cancer, was shown to be feasible. Within the clinical context, 3D models were used to identify vascular anomalies, for surgical planning and navigation in lateral pelvic wall lymph node dissection and in management of recurrent rectal cancer. Both physical and virtual 3D models were found to be valuable in surgical education, with a preference for 3D printed models. The main limitations of the current technology identified in the studies were related to the restrictions of the segmentation process and the lack of 3D printing materials that could mimic the soft and deformable tissues.

CONCLUSION

3D modelling technology has potential to be utilised in multiple aspects of rectal cancer surgery, however, it is still at the experimental stage of application in this setting.

Multidisciplinary management of early rectal cancer - The role of surgical local excision in current and future clinical practice

The implementation of bowel cancer screening programs has led to a rise in the incidence of early rectal cancer. The combination of increased incidence and the growing interest in organ-sparing treatment options has led to an amplified importance of local excision techniques in treatment strategies for early rectal cancer. In addition, developments in new technologies of single-port surgery have popularized surgical techniques. Although local treatment of early rectal cancer seems promising, a multidisciplinary approach is necessary and awareness of the oncological robustness is warranted to enable shared decision-making. This review illustrates the position of surgical local excision in the treatment of early rectal cancer and reflects on its role in current and future clinical practice.

Meaningful words in rectal MRI synoptic reports: How "polypoid" may be prognostic

PURPOSE

This study explored the clinicopathologic outcomes of rectal tumor morphological descriptors used in a synoptic rectal MRI reporting template and determined that prognostic differences were observed.

METHODS

This retrospective study was conducted at a comprehensive cancer center. Fifty patients with rectal tumors for whom the synoptic descriptor "polypoid" was chosen by three experienced radiologists were compared with ninety comparator patients with "partially circumferential" and "circumferential" rectal tumors. Two radiologists re-evaluated all cases. The outcome measures were agreement among two re-interpreting radiologists, clinical T staging with MRI (mrT) and descriptive nodal features, and degrees of wall attachment of tumors (on MRI) compared with pathological (p) T and N stage when available.

RESULTS

Re-evaluation by two radiologists showed moderate to excellent agreement in tumor morphology, presence of a pedicle, and degree of wall attachment (k = 0.41-0.76) and excellent agreement on lymph node presence and size (ICC = 0.83-0.91). Statistically significant lower mrT stage was noted for polypoid morphology, wherein 98% were mrT1/2, while only 7% and 2% of partially circumferential and circumferential tumors respectively were mrT1/2. Pathologic T and N stages among the three morphologies also differed significantly, with only 14% of polypoid cases higher than stage pT2 compared to 48% of partially circumferential cases and 60% of circumferential cases.

CONCLUSION

Using a "polypoid" morphology in rectal cancer MRI synoptic reports revealed a seemingly distinct phenotype with lower clinical and pathologic T and N stages when compared with alternative available descriptors.

PRECIS

"Polypoid" morphology in rectal cancer confers a lower clinical and pathologic T and N stage and may be useful in determining whether to proceed with surgery versus neoadjuvant treatment.

The utility of preoperative radiological evaluation of early rectal neoplasia: a systematic review and meta-analysis

AIM

The diagnostic role for preoperative imaging of clinically benign rectal adenomas is unclear. The objective of this systematic review and meta-analysis was to examine the diagnostic accuracy of preoperative imaging in distinguishing benign adenomas from rectal cancer.

METHOD

A systematic search was performed for all studies published that correlated staging of clinically benign rectal adenomas with endorectal ultrasound (ERUS) or MRI and histology. Imaging was compared with postoperative histology and data on the numbers of true positives, false positives, true negatives and false negatives were extracted. Summary estimates of sensitivity and specificity with 95% CIs were calculated using a bivariate random effects model. The QUADAS2 tool was used to determine the methodological quality of included studies.

RESULTS

Eleven studies describing 1511 patients were retrieved. A total of 1134 patients underwent local excision and 377 had a formal proctectomy. A benign rectal adenoma was diagnosed in 840 and 214 had a T1 rectal cancer. For confirming benign adenomas, the pooled sensitivity of ERUS was 0.81 (95% CI 0.69-0.89) and specificity was 0.85 (95% CI 0.68-0.93). For detecting occult T1 tumours, the pooled sensitivity of ERUS was 0.50 (95% CI 0.33-0.66) and specificity was 0.89 (95% CI 0.82-0.94). Quantitative analysis of MRI could not be performed due to insufficient studies.

CONCLUSION

This study demonstrates the limited accuracy of preoperative ERUS in distinguishing benign adenomas from T1 rectal cancer. Preoperative imaging must be interpreted with caution to prevent over-staging and unnecessary proctectomy. We propose that clinically benign lesions may undergo local excision, with subsequent management based on final histology.

MRI cT1-2 rectal cancer staging accuracy: a population-based study

Background

Adequate MRI‐based staging of early rectal cancers is essential for decision‐making in an era of organ‐conserving treatment approaches. The aim of this population‐based study was to determine the accuracy of routine daily MRI staging of early rectal cancer, whether or not combined with endorectal ultrasonography (ERUS).

Methods

Patients with cT1–2 rectal cancer who underwent local excision or total mesorectal excision (TME) without downsizing (chemo)radiotherapy between 1 January 2011 and 31 December 2018 were selected from the Dutch ColoRectal Audit. The accuracy of imaging was expressed as sensitivity, specificity, and positive predictive value (PPV) and negative predictive value.

Results

Of 7382 registered patients with cT1–2 rectal cancer, 5539 were included (5288 MRI alone, 251 MRI and ERUS; 1059 cT1 and 4480 cT2). Among patients with pT1 tumours, 54·7 per cent (792 of 1448) were overstaged by MRI alone, and 31·0 per cent (36 of 116) by MRI and ERUS. Understaging of pT2 disease occurred in 8·2 per cent (197 of 2388) and 27·9 per cent (31 of 111) respectively. MRI alone overstaged pN0 in 17·3 per cent (570 of 3303) and the PPV for assignment of cN0 category was 76·3 per cent (2733 of 3583). Of 834 patients with pT1 N0 disease, potentially suitable for local excision, tumours in 253 patients (30·3 per cent) were staged correctly as cT1 N0, whereas 484 (58·0 per cent) and 97 (11·6 per cent) were overstaged as cT2 N0 and cT1–2 N1 respectively.

Conclusion

This Dutch population‐based analysis of patients who underwent local excision or TME surgery for cT1–2 rectal cancer based on preoperative MRI staging revealed substantial overstaging, indicating the weaknesses of MRI and missed opportunities for organ preservation strategies.