Microscopic spread of low rectal cancer in regions of the mesorectum: detailed pathological assessment with whole-mount sections

A comparison of whole-mount and conventional sections for pathological mesorectal extension and circumferential resection margin assessment after total mesorectal excision

INTRODUCTION

The objective of the study is to compare 2 techniques for histological handling of rectal cancer specimens, namely whole-mount in a large block vs conventional sampling using small blocks, for mesorectal pathological assessment of circumferential resection margin status and depth of tumor invasion into the mesorectal fat.

METHODS

This is a prospective study including 27 total mesorectal excision specimens of rectal cancer from patients treated for primary rectal carcinoma between 2020 and 2022 in a specialized multidisciplinary Colorectal Unit. For each total mesorectal excision specimen, 2 contiguous representative tumoral slices were selected and comparatively analyzed with whole-mount and small blocks macroscopic dissection techniques, enabling comparison between them in the same surgical specimen. The agreement between the 2 techniques to assess the distance of the tumor from the circumferential resection margin as well as the depth of tumor invasion was evaluated with the Student's t-test for paired samples, Pearson's correlation coefficient, and the Bland-Altman method comparison analysis.

RESULTS

Complete mesorectal excision was observed in 8% of cases. Circumferential resection margin involvement was observed in only one case (4 %). The whole-mount and small block techniques obtained similar results when we assessed the distance to the circumferential resection margin (t-test P = 0.8, r = 0.92) and the depth of mesorectal infiltration (t-test P = 0.6, r = 0.95).

CONCLUSIONS

Both gross dissection techniques (whole-mount vs multiple small cassettes) are equivalent and reliable to assess the distance to circumferential resection margin and the depth of mesorectal infiltration in the mesorectal fat in rectal cancer staging.

Complete mesogastric excision for gastric cancer: is it the future of gastric cancer surgery?

Gastric cancer remains undoubtedly one of the most common and deadly cancers worldwide. The global incidence shows wide geographic variation with a high prevalence in Asia. Besides that, there are evident differences in epidemiology, histopathology, tumor location, diagnosis and treatment strategy between east and west countries. Gastric cancer represents an aggressive disease, with many factors influencing its development and also recurrence after surgical resection. New knowledge of disease spread and new routes of metastases are now emerging and the 'novel' concept of complete mesogastric excision for gastric cancer is under consideration and debate. This article aims to analyze and highlight this new concept after a careful literature review, offering also a view toward the future.

Required distal mesorectal resection margin in partial mesorectal excision: a systematic review on distal mesorectal spread

BACKGROUND

The required distal margin in partial mesorectal excision (PME) is controversial. The aim of this systematic review was to determine incidence and distance of distal mesorectal spread (DMS).

METHODS

A systematic search was performed using PubMed, Embase and Google Scholar databases. Articles eligible for inclusion were studies reporting on the presence of distal mesorectal spread in patients with rectal cancer who underwent radical resection.

RESULTS

Out of 2493 articles, 22 studies with a total of 1921 patients were included, of whom 340 underwent long-course neoadjuvant chemoradiotherapy (CRT). DMS was reported in 207 of 1921 (10.8%) specimens (1.2% in CRT group and 12.8% in non-CRT group), with specified distance of DMS relative to the tumor in 84 (40.6%) of the cases. Mean and median DMS were 20.2 and 20.0 mm, respectively. Distal margins of 40 mm and 30 mm would result in 10% and 32% residual tumor, respectively, which translates into 1% and 4% overall residual cancer risk given 11% incidence of DMS. The maximum reported DMS was 50 mm in 1 of 84 cases. In subgroup analysis, for T3, the mean DMS was 18.8 mm (range 8-40 mm) and 27.2 mm (range 10-40 mm) for T4 rectal cancer.

CONCLUSIONS

DMS occurred in 11% of cases, with a maximum of 50 mm in less than 1% of the DMS cases. For PME, substantial overtreatment is present if a distal margin of 5 cm is routinely utilized. Prospective studies evaluating more limited margins based on high-quality preoperative magnetic resonance imaging and pathological assessment are required.

Mesorectal radiotherapy for early stage rectal cancer: A novel target volume

With the introduction of population-based bowel cancer screening, rectal cancer is diagnosed at earlier stages, yet standard treatment still requires the same extensive surgery that is used for more advanced stages. Organ preserving treatment is rapidly developing and is subject of investigation in numerous clinical trials. The STAR-TREC trial is an international, multi-centre randomised trial investigating organ preservation using (chemo)radiotherapy. Patients with small mrT1-3bN0V0M0 tumours are randomized between three arms: standard TME, organ preservation with SCRT or with CRT. In this trial, the clinical target volume has been tailored to the early staged disease of the included patients. This mesorectal irradiation volume includes the mesorectum and pre-sacral lymph nodes at the level of the tumour, two centimetres below and cranially up to the S2-3 interspace level. In contrast to conventional irradiation volumes, the lateral lymph nodes and the nodes along the superior rectal artery are excluded. As a result, the dose to the bowel, bladder, anal sphincter and the neurovascular plexus in the lower pelvis is substantially decreased, especially when combined with modern irradiation techniques, such as dynamic arc therapy. These lower doses are expected to lead to decreasing acute and late toxicity and beneficial functional outcomes. The implementation of this novel target volume will be accompanied by an extensive quality assurance program in the STAR-TREC trial. We describe the rationale behind the novel, mesorectal only radiotherapy treatment used in the STAR-TREC trial specifically tailored for early stage disease, with the goal of organ preservation.

[Pathology of the R1 classification in visceral cancer surgery]

The completeness of tumor removal is described in the residual tumor classification (R classification). The R category of a surgical specimen reflects the effects of treatment, influences further treatment decisions and is associated with patient survival. Thorough pathological examination of all resection planes, including the circumferential margin, is necessary for accurate classification.

Detection and Characterization of Metastatic Cancer Cells in the Mesogastrium of Gastric Cancer Patients

Gastric cancer is the second leading cause of cancer death worldwide. Here, we propose a novel type of tumor metastasis designated as Metastasis V in gastric cancer. Metastasis V is defined as the appearance of cancer cells in the mesogastrium with perigastric adipose tissue. To detect its incidence and characterize its clinic pathological features, large cross sectional tissue analysis of mesogastrium from 74 patients were used. Metastasis V was detected in 1 of 40 (2.5%) patients with early gastric cancer, 8 of 34 (24%) patients with advanced gastric cancer. The mean distance of Metastasis V from gastric wall was approximately 2.6 cm. Metastasis V was closely associated with tumor invasion depth, along with a number of positive lymph node metastasis. The prognosis of patients with Metastasis V was significantly (P<0.05) worse than those with tumor cell-free mesogastrium. These findings indicate that by using whole-sectional analysis, Metastasis V can be detected in the mesogastrium of gastric cancer patients, and also suggests that it may be a risk factor for patient survival after radical surgery.

Multiparametric MRI of rectal cancer in the assessment of response to therapy: a systematic review

BACKGROUND

Conventional MRI is limited in the assessment of nodal status and T status after neoadjuvant chemoradiotherapy. Multiparametric MRI strives to overcome these issues by directly measuring the local microcirculation and cellular environment, thus possibly allowing for a more reliable evaluation of response to therapy.

OBJECTIVE

We assessed the available literature for the value of multiparametric MRI sequences (diffusion-weighted and dynamic contrast-enhanced imaging) in determining the response to neoadjuvant chemoradiotherapy in patients with rectal cancer.

DATA SOURCES

We conducted a systematic literature research in the PubMed database.

STUDY SELECTION

English-language publications of the years 2000-2013 that applied multiparametric MRI in the neoadjuvant setting were included in this study.

INTERVENTION

Patients received neoadjuvant chemoradiotherapy and MRI examinations for staging and assessment of response.

MAIN OUTCOME MEASURES

Accuracy, specificity, and sensitivity of MRI in prediction/assessment of response to therapy were the included measures.

RESULTS

Forty-three studies were included in this review; 30 of them included diffusion-weighted imaging sequences, and 13 included dynamic contrast-enhanced MRI. Conventional MRI is limited in the accuracy of both T and N stages and response assessment. Diffusion-weighted imaging and dynamic contrast-enhanced MRIs showed additional value in both the prediction and detection of (complete) response to therapy compared with conventional sequences alone, as well as in correct N staging along with new experimental contrast agents.

LIMITATIONS

The lack of standardization represents an important technical limitation. Most studies are conducted in an experimental setting; therefore, larger multicenter prospective studies are needed to verify the present findings.

CONCLUSIONS

Advanced, functional MRI techniques allow for the quantification of tumor biological processes, such as microcirculation, vascular permeability, and tissue cellularity. This new technology has begun to show potential advantages over standard morphologic imaging in the restaging of rectal cancer, allowing for more accurate prognostication of response and potentially introducing an era allowing earlier treatment alteration and more accurate noninvasive surveillance, which could improve patient outcomes.

Optimal colorectal cancer staging criteria in TNM classification

PURPOSE

Histologic components of the TNM classification system have been repeatedly revised since the fifth edition (TNM5). TNM classification revisions provide different criteria for categorizing tumor nodules without residual lymph node structure (ND). However, there are few systematic evaluations regarding the effectiveness of these revisions.

PATIENTS AND METHODS

A multicenter pathologic review for ND in colorectal cancer (CRC) was performed. Tumor staging defined by TNM5, sixth edition (TNM6), and seventh edition (TNM7) were compared on the basis of Akaike information criterion (AIC) and Harrell's concordance index (c-index). Moreover, TNM7's prognostic value was compared between the original ND and modified criteria, which considered all regional NDs as lymph node metastasis (LNM) irrespective of the original structure.

RESULTS

In 1,716 treated patients with CRC (1994 to 1998), tumor stages (I/II/III) exhibited better prognoses in TNM7 (AIC, 3055.1; c-index, 0.7215) than in TNM6 (AIC, 3063.7; c-index, 0.7149), but not better than in TNM5 (AIC, 3051.6; c-index, 0.7240). Comparing the original TNM7 and modified criteria, 4.2% of patients were classified in different N stages (N0/N1/N2a/N2b); both AIC and the c-index were superior in the modified criteria (AIC, 3029.40; c-index, 0.7271) compared with the original criteria (AIC, 3040.58; c-index, 0.7230). Modified criteria were also associated with improved prognostic power of tumor stages (I/IIA/IIB/IIC/IIIA/IIIB/IIIC). These results were similar in another cohort of 2,242 treated patients with CRC (1999 to 2003).

CONCLUSION

The prognostic value of TNM7 is better than that of TNM6; however, improvement over TNM5 is insignificant. By considering all regional NDs as LNM irrespective of their morphology, TNM classification can be simplified and its prognostic value improved.

Actual Status of Distribution and Prognostic Impact of Extramural Discontinuous Cancer Spread in Colorectal Cancer

Purpose

To clarify the prognostic impact of tumor nodules without residual lymph node (LN) structure (ND) in colorectal cancer and to determine optimal categorization of ND in tumor staging.

Patients and Methods

A multicenter, retrospective pathologic review was performed for 1,716 patients with stages I to III curatively resected colorectal cancer treated at 11 institutions between 1994 and 1998. An additional 2,242 patients from nine institutions were enrolled between 1999 and 2003 as a second cohort to validate the results.

Results

LN metastasis (LNM) and ND were observed in 33.7% and 16.0% (smooth-contour nodule [S-ND], 8.2%; irregular-contour nodule [I-ND], 10.7%) of patients in the first cohort. S-ND and I-ND were similarly distributed in the regional area. There was no considerable difference in the impact on survival between S-ND (hazard ratio [HR], 2.7; 95% CI, 1.9 to 3.8) and I-ND (HR, 4.3; 95% CI, 3.3 to 5.8) or between LNM (HR, 4.5; 95% CI, 3.4 to 6.0) and ND (HR, 4.0; 95% CI, 3.1 to 5.3). LNM and ND were similarly associated with the mode of recurrence. Tumor nodules ≥ 5 mm growing with venous/perineural invasion (ND [v/pni+]), judged with 0.61 κ value among 11 observers, had an independent prognostic value for 5-year survival of 42%; similar results were observed in the second cohort.

Conclusion

These results do not support the TNM system in which S-ND is treated differently from I-ND in tumor staging; LNM and ND should be considered together in the same category. The presence of ND (v/pni+) has a considerable adverse prognostic effect.

[Pathological work-up of rectal cancer following partial/total mesorectal excision]

Total mesorectal excision (TME) refers to the anatomically accurate surgical resection of the rectum from its surrounding fascias and has become the gold standard for treating rectal cancer. The pathologist plays a key role in the assessment of these specimens and good pathological reporting of rectal cancer is essential to achieving the optimum possible results for patients with rectal cancer. In experienced hands, these techniques result in a dramatic improvement in cancer-related cure rates from 45% to 75% and a reduction in pelvic recurrences from 40% to 5%-10%. Moreover, preservation of sexual and urinary functions is possible in the majority of cases. This article reviews the pathological assessment of the TME specimen in detail with regards to current international guidelines and describes its anatomical background. In addition, particular issues relating to margins, lymph node dissection and effects of neoadjuvant therapy are discussed.

Change in glucose metabolism measured by 18F-FDG PET/CT as a predictor of histopathologic response to neoadjuvant treatment in rectal cancer

PURPOSE

In order to analyze the changes of glucose metabolism by maximum standardized uptake value (SUVmax) of 18F-FDG PET/CT in patients with rectal cancer submitted to neoadjuvant radiochemotherapy (nRCT) and to correlate SUV changes with tumor regression grade (TRG).

METHODS AND MATERIAL

Three sequential 18F-FDG PET/CT studies were performed in 31 patients with rectal cancer at the following time point: before starting the treatment (PET/CT1), during the treatment (PET/CT2), and after completion of neoadjuvant treatment (PET/CT3). The SUVmax values of the rectal lesion in the PET/CT1 (SUV1), PET/CT2 (SUV2), and PET/CT3 (SUV3) were obtained; deltaSUV1 [(SUV1 - SUV2)/SUV1] and deltaSUV2 [(SUV1 - SUV3)/SUV1] were also calculated. Metabolic parameters were compared to TRG.

RESULTS

Significant differences in pathologic responder and non-responder patients were found only for SUV2 (6.4 ± 2.9 in responder and 10.7 ± 4.8 in non-responder patients, respectively; P = 0.006) and SUV3 (3.6 ± 1.4 in responder and 6.6 ± 2.1 in non-responder patients, respectively; P = 0.0009). The best predictor for TRG response was SUV3 (threshold of 4.4) with sensitivity, specificity, accuracy, negative predictive value, and positive predictive value of 77.3%, 88.9%, 80.7%, 61.5%, and 94.4%, respectively.

CONCLUSION

18F-FDG PET/CT is a reliable and accurate technique to assess the response to nRCT in rectal cancer. In our population, the absolute value of SUVmax after treatment was the best predictor of pathological response.

Clinical impact of mesorectal extranodal cancer tissue in rectal cancer: detailed pathological assessment using whole-mount sections

PURPOSE

Mesorectal cancer deposits showing no histological evidence of lymph node structure (extranodal cancer tissue) are a common feature in rectal cancer. However, optimal categorization of extranodal cancer tissue using TNM grading is not yet established. We reviewed extranodal cancer tissue in detail using whole-mount sections to clarify its clinical impact.

METHODS

This retrospective study involved 214 consecutive patients with stage I-III rectal cancer. After fixation, the whole tumor mass including the mesorectum was sliced into longitudinal sections and stained. Mesorectal involvement was classified as direct tumor infiltration, lymph node involvement, or extranodal cancer tissue. Extranodal cancer tissue was classified morphologically, and its maximum size and distance from the primary tumor were measured. The clinical impact of extranodal cancer tissue was evaluated by univariate and multivariate analyses.

RESULTS

: A total of 498 extranodal cancer deposits were detected in 88 patients (41.1%). Multivariate Cox proportional hazards model analysis indicated that the presence of extranodal cancer tissue was an independent prognostic factor for relapse-free (P < .001) and overall survival (P = .003). The hazard ratio for extranodal cancer tissue was higher than for nodal involvement, irrespective of morphological classification. The clinical impact differed significantly with the number of histological types of extranodal cancer tissue, the number of deposits, their maximum size, and their distance from the primary tumor.

CONCLUSIONS

In the present study, we have shown that extranodal cancer tissue detected by whole-mount sections has a clinical impact that is more severe than nodal involvement.

Patterns of local recurrence in rectal cancer; a study of the Dutch TME trial

AIM OF THE STUDY

In patients from the Dutch TME trial patterns of local recurrence (LR) in rectal cancer were studied. The purpose was to reconstruct the most likely mechanisms of LR and the effect of preoperative radiotherapy.

METHODS

1417 patients were analyzed; 713 were randomized into preoperative radiotherapy and total mesorectal excision (RT + TME), 704 into TME alone. Of the 114 patients with LR, the subsites of LR were determined and related to tumor and treatment factors.

RESULTS

Overall 5-year LR-rate was 4.6% in the RT + TME group and 11.0% in the TME group. Presacral local recurrences occurred most in both groups. Radiotherapy reduced anastomotic LR significantly, except when after low anterior resection (LAR) distal margins were less than 5 mm. Abdominoperineal resection (APR) mainly resulted in presacral LR. Even after resection with a negative circumferential resection margin, LR-rates were high. Thirty percent of the patients had advanced tumors, which resulted in 58% of all LRs. Lateral LR comprised 20% of all LR. Presacral and lateral LR resulted in a poor prognosis, in contrast to anterior or anastomotic LRs with a relatively good prognosis.

CONCLUSIONS

RT reduces LR in all subsites and is especially effective in preventing anastomotic LR after LAR. APR-surgery mainly results in presacral LR, which may be prevented by a wider resection. In the TME trial many advanced tumors were included, rather requiring chemoradiotherapy instead of RT. Currently, with good imaging techniques, better selection can take place. Especially lateral LR might be a problem in the future.

Occurrence and prognostic value of circumferential resection margin involvement for patients with rectal cancer

BACKGROUND AND AIM

Total mesorectal excision (TME) was advocated owning to the reduction in local failure, while deficiency in pathologic details limited monitoring of surgical quality assurance. Here, we aimed to examine circumferential resection margin (CRM) by large tissue slice, discussing its rule in occurrence and relationship with prognosis, thus providing proof for the adoption of TME principles and the application of adjuvant therapy.

MATERIALS AND METHODS

Specimens of 106 patients with rectal cancer, who underwent potentially curative resection from December 2001 to September 2002, were examined. Follow-up data were collected.

RESULTS

Altogether, 2,068 mesorectal nodes were examined with 272 involved by tumor. CRM involvement (CRMI) was examined in 20 specimens. In these 20 cases, seven, nine, and four were caused by tumor infiltration, lymph node metastasis, and both, respectively. Occurrence of CRMI was more common for lower-located cancers while also statistically related to tumor differentiation, infiltration, and lymph node metastasis. The difference in local recurrence rate, general recurrence rate, disease-free survival rate, and overall survival rate between the group with CRMI and the group without were all proven to be significant.

CONCLUSIONS

Detailed pathologic examination, including status of CRM, is advocated since it provides accurate prognostic information. Surgeons could maximize the probability of cure by following the principle of TME. Preoperative adjuvant therapy was essential for advanced staged and lower-located lesions, which implied likelihood of CRMI.

Adjuvant and neoadjuvant chemoradiation or radiotherapy in rectal cancer--a review focusing on open questions

BACKGROUND

The therapy of rectal cancer has been a matter of debate since decades, especially with regard to the benefits of neoadjuvant or adjuvant therapies. Principles of additional therapies have been established nearly two decades ago and are questioned nowadays on the basis of more recently modified operative techniques. Benefits and sequelae of therapies have to be balanced against each other, and it seems somewhat likely that a more differentiated strategy than simply stating that every patient with stage II and III rectal cancer needs chemoradiation or radiotherapy will, in long term, be recommended.

CONCLUSION

It should be kept in mind that results of centers of excellence and of phase-III studies with their positively selected patient populations are not representative for all the patients with rectal cancer and physicians treating them.

Colorectal tumour deposits in the mesorectum and pericolon; a critical review

Although tumour deposits (TD) in the pericolic and mesorectal fat have been recognized since 1935, incorporation in the Tumour Node Metastasis (TNM)/American Joint Committee on Cancer (AJCC) system took place in 1997. The 3-mm rule classified TD as lymph node metastases. This rule was changed in 2002, when the contour of the deposit became the diagnostic feature. This review has evaluated the 3714 patients described in the literature. The incidence of TD varies from 5 to 45%. Their origin has been shown to be heterogeneous; however, their presence indicates a poorer survival. The hazard ratio for death due to disease is 1.96. Various studies have tried to determine the importance of types of TD, based on contour, size and origin, but all fail to provide an evidence base to substantiate its use in the TNM system. To classify TD as positive lymph nodes after neoadjuvant therapy is a misconception, since the presence of tumour microfoci after therapy can be a sign of good response to treatment and indicative of a good prognosis. In conclusion, we did not find adequate evidence for the inclusion of TD in TNM/AJCC staging systems. Moreover, the current directives are confusing, and the definitions should not be used after neoadjuvant therapy.

Distribution and patterns of lymph nodes metastases and micrometastases in the mesorectum of rectal cancer

BACKGROUND AND OBJECTIVES

Facts buried in the mesorectum remain to be unveiled. This study investigated the number, size, and detailed distribution of lymph nodes metastases and micrometastases within the mesorectum of rectal cancer.

METHODS

Thirty-one patients who underwent total mesorectal excision (TME) were treated with lymph node revealing solution to retrieve lymph nodes, which were submitted to hematoxylin and eosin (HE) examination and immunohistochemical (IHC) staining.

RESULTS

The mean number of mesorectal nodes per case was 17.7. The mean size of metastatic, micrometastatic, and isolated tumor cells (ITC) harbored nodes was 5.2 mm, 4.5 mm, and 3.3 mm, respectively. Most of the metastatic (92.1%), micrometastatic and ITC-involved nodes (69.2%) were located along the superior rectal artery (SRA). Posterior-wall located tumor might spread along both sides of the mesorectum simultaneously (P = 0.34), while lateral-wall located tumor spread preferably to ipsolateral side versus contralateral side (P = 0.012).

CONCLUSION

Most of the metastases and micrometastases positive lymph nodes were smaller than 5 mm and distributed along the SRA. The patterns of lymph nodes spread were related to the circumferential situation of tumor in the rectal wall. Surgical excision of the rectal cancer should completely remove the whole mesorectum, especially to avoid any damage of the mesorectum on tumor side.

The total mesorectal excision specimen for rectal cancer: a review of its pathological assessment

Total mesorectal excision (TME) refers to the surgical removal of the complete perirectal soft tissue envelope, using sharp instruments under direct vision, and has become the contemporary standard of care for patients with rectal cancer. Pathologists play a key role in the evaluation of these specimens, including the quality assurance of surgical performance, as well as evaluation of the circumferential radial margin (CRM). While the latter is the most significant predictor of local recurrence, the quality of the excised mesorectum is another important factor in assessing the risk of local recurrence in patients with a negative CRM. Since proper pathological assessment of the TME specimen provides important prognostic information, as well as critical feedback to surgeons regarding technical performance, it is important to have adequate guidelines for the macroscopic handling of these specimens. The CLASSICC study of the Medical Research Council in the United Kingdom, as well as the Dutch TME trial have introduced a new standard for the pathological assessment of TME specimens, including an approach that involves assessment in both the fresh and fixed states, at least 48 hours of fixation of an intact specimen, with observations made on both the external appearance and cross-sectional slices. This article reviews the pathological assessment of the TME specimen, including basic definitions, current international guidelines, an approach to evaluating the mesorectum and a discussion of special issues relating to margins, lymph node retrieval and effects of neoadjuvant therapy.