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Objective

Tumor deposits (TDs) are a negative prognostic factor in colorectal cancer, independent of lymph node metastasis (LNM). This study aimed to investigate the ability of pre-operative MRI to identify TDs and differentiate them from LNM in rectal cancer.

Materials and methods

Patients with histopathological N1-N2 rectal cancer with and without TDs who underwent curative-intent primary surgery between 2013 and 2023 were retrospectively included. Three radiologists independently reviewed pre-operative MR images for the presence of TDs and LNM. Histopathology served as the reference standard from which interobserver agreement by Cohen’s kappa (κ) was calculated. Unblinded node-to-node comparison of MRI and histopathological images was used to identify sources of discrepancies between the modalities. Post hoc analysis stratified on nodal size (> or ≤ 5 mm) was performed.

Results

Eighty-eight patients (50% with TDs on histopathology, 74% male, median age 70 [20–89] years) were included, of whom 27 were excluded due to poor image quality. Agreement between MRI and histopathology (p), both for TD-presence (κ = −0.04) and LNM-presence (κ = 0.16), was low. In the node-by-node comparison, 43 out of 50 pTDs (86%) measured ≤ 5 mm, and 131 of 167 pLNM (78%) measured ≤ 5 mm. In post hoc analysis of smaller (≤ 5 mm) nodules, no pTDs and 3% of pLNM were diagnosed using MRI.

Conclusion

MRI demonstrated limited ability in detecting and differentiating TDs and LNM in pre-operative low-risk patients. Diagnostic performance was particularly poor for nodules ≤ 5 mm, which constituted 174 out of 217 (80%) pathological nodular structures.

Purpose The aim of this study was to evaluate the possible risk factors for developing a parastomal hernia (PSH) in a cohort of rectal cancer patients with and without the application of a retro-muscular prophylactic mesh. The evaluated risk factors included the position of the stoma in the rectus abdominis muscle (RAM), RAM atrophy and shift of abdominal wall midline structures. Methods Rectal cancer patients treated with an abdominoperineal excision or Hartmann's procedure between 2002 and 2015 at Vastmanland Hospital, Sweden was included. Postoperative CT examinations were retrospectively reviewed regarding the presence of PSH and RAM atrophy and for measurements such as position of the stoma in the RAM. Results 116 patients were included, with a median age of 71 years. 70 patients received a prophylactic stoma mesh. 55 patients (47%) had a parastomal hernia at three-year follow-up. Rectus abdominis muscle atrophy was significantly higher in the mesh group compared with the non-mesh group (37% vs 2%; P = 0.04). RAM atrophy was a significant independent protective factor for developing a PSH (P = 0.007; OR 0.15; 95% CI 0.03-0.55). Conclusion Placement of a prophylactic retro-muscular stoma mesh resulted in a high frequency of RAM atrophy distal to the stomal aperture and patients with such atrophy had a lower risk of developing a PSH.

Purpose

The primary aim of this study was to investigate whether rectus abdominis muscle atrophy is associated with a lower risk of developing parastomal hernia. Secondary objectives were to assess whether the use of prophylactic mesh is a risk factor for rectus abdominis muscle atrophy and whether the position of the stoma within the rectus abdominis muscle affects the risk of parastomal hernia.

Methods

This retrospective study analysed patients from a prospective, randomised, multicentre trial in which rectal cancer patients were randomised to stoma creation with or without prophylactic mesh. Computed tomography at 12 months was evaluated to identify parastomal hernia, rectus abdominis muscle atrophy and position of stoma in the rectus abdominis muscle.

Results

Out of 149 patients, rectus abdominis muscle atrophy was observed in 9% and parastomal hernia in 42% of patients. There was no association between rectus abdominis muscle atrophy and parastomal hernia (p = 0.80; RR 1.07; CI 0.62–1.86), nor between prophylactic mesh and rectus abdominis muscle atrophy (p = 0.19; RR 2.00; CI 0.7–5.73). Stoma placement within the rectus abdominis muscle also showed no association with parastomal hernia development (p = 0.69; RR 0.97; CI 0.81–1.15).

Conclusion

This study found no statistically significant association between rectus abdominis muscle atrophy and parastomal hernia. The use of prophylactic mesh was not a risk factor for rectus abdominis muscle atrophy, and stoma placement within the rectus abdominis muscle was not associated with parastomal hernia. The previously reported association between prophylactic mesh, rectus abdominis muscle atrophy, and parastomal hernia was not confirmed in this cohort.