Predicting oncologic outcomes by stratifying mesorectal extension in patients with pT3 rectal cancer: A Japanese multi-institutional study

The percentage of mesorectal infiltration as a prognostic factor after curative surgery for pT3 rectal cancer

AIM

The aim of this study is to evaluate the prognostic value of a novel variable - the percentage of mesorectal infiltration (PMI) - in pT3 rectal cancer.

METHOD

A cohort of 241 patients with pT3 rectal adenocarcinoma, operated on between February 2002 and May 2019, was selected for the analysis. Data concerning patient, treatment and tumour characteristics were collected. The depth of mesorectal infiltration (DMI) and the distance between the deepest invasion and the circumferential resection margin (CRM) were measured. The PMI was calculated using a formula combining these parameters.

RESULTS

Neoadjuvant therapy was administered in 33.2% of cases. A complete mesorectal excision was achieved in 74% of patients. The CRM was affected in 24 patients (9.9%). The 5-year actuarial local recurrence (LR), overall recurrence (OR) and overall survival (OS) rates were 7.5%, 22.9% and 72.4%, respectively. The PMI was significantly associated with worse oncological outcomes regarding LR (p = 0.009), OR (p = 0.001) and OS (p = 0.016) rates. A cut-off value of PMI >60% had the highest specificity (80%) for LR (p = 0.026), OR (p = 0.04) and OS (p = 0.07).

CONCLUSION

The PMI has an adverse prognostic impact on the oncological results following surgery for pT3 rectal cancer. It allows prediction of the risk of both LR and distant recurrence with higher accuracy than the DMI or the distance to the CRM. A PMI >60% may be used as a cut off value while subclassifying pT3 rectal tumours. It may influence decision-making while establishing adjuvant treatment and the follow-up schedule.

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.

Percentage of Tumor Invasion at Pretreatment High-Resolution Magnetic Resonance Imaging: Associating With Aggressive and Tumor Response in Chinese T3 Rectal Cancer-Preliminary Results

Purpose

The purpose of the study was to assess the ability of percentage of tumor invasion (PTI) of T3 rectal cancer on pretreatment MRI as an imaging biomarker to reflect aggressiveness and to predict tumor response after neoadjuvant chemoradiation (NCRT) in Chinese population.

Methods

A total of 107 Chinese rectal cancer patients who underwent pretreatment MRI staging as T3 were included. The extramural depth of tumor invasion (EMD), the distance between outer border of muscularis propria (MP) and mesorectal fascia (MRF) we called "thickness of the mesorectum (TM)") at the same slice and direction were measured at pretreatment MRI, and PTI was equal to EMD/TM, was calculated. The EMD and PTI of subgroups based on pretreatment CEA, CA19-9 levels; N category and pathological complete response (pCR) were compared. The parameters, which described tumor invasion, were compared between pCR and non-pCR group. Student t-tests and logistic analysis were applied.

Results

The pretreatment PTI was higher in CEA ≥5.2 ng/ml patients (58.52% ± 27.68%) than in CEA <5.2 ng/ml patients (47.27% ± 24.15%) (p = 0.034). The pretreatment EMD in non-pCR group (7.21 ± 2.85 mm) was higher than in pCR group (6.14 ± 3.56 mm) (p = 0.049). The pretreatment PTI in non-pCR group (57.4% ± 26.4%) was higher than in pCR group (47.3% ± 29.1%) (p = 0.041). Compared with patients with PTI ≥50%, MRF (+), more patients with PTI <50%, MRF (-) showed pCR (OR = 8.44, p = 0.005; OR = 6.32, p = 0.024).

Conclusion

The PTI obtained at pretreatment MRI may serve as an imaging biomarker to reflect tumor aggressiveness and predict which T3 rectal cancer patients may benefit from NCRT in Chinese population.

Correlation Between the Distance to Mesorectal Fascia and Prognosis of cT3 Rectal Cancer: Results of a Multicenter Study From China

BACKGROUND

The cT3 substage criteria based on extramural depth of tumor invasion in rectal cancer have several limitations.

OBJECTIVE

This study proposed that the distance between the deepest tumor invasion and mesorectal fascia on pretherapy MRI can distinguish the prognosis of patients with cT3 rectal cancer.

DESIGN

This is a cohort study.

SETTING

This study included a prospective, single-center, observational cohort and a retrospective, multicenter, independent validation cohort.

PATIENT

Patients who had cT3 rectal cancer with negative mesorectal fascia undergoing neoadjuvant chemoradiotherapy followed by radical surgery were included in 4 centers in China from January 2013 to September 2014.

INTERVENTION

Baseline MRI with the distance between the deepest tumor invasion and mesorectal fascia, extramural depth of tumor invasion, and mesorectum thickness were measured.

MAIN OUTCOME MEASURES

The cutoff of the distance between the deepest tumor invasion and mesorectal fascia was determined by time-dependent receiver operating characteristic curves, supported by a 5-year progression rate from the prospective cohort, and was then validated in a retrospective cohort.

RESULTS

There were 124 and 274 patients included in the prospective and independent validation cohorts. The distance between the deepest tumor invasion and mesorectal fascia was the only predictor for cancer-specific death (HR, 0.1; 95% CI, 0.0-0.7) and was also a significant predictor for distant recurrence (HR, 0.4; 95% CI, 0.2-0.9). No statistically significant difference was observed in prognosis between patients classified as T3a/b and T3c/d.

LIMITATIONS

The sample size is relatively small, and the study focused on cT3 rectal cancers with a negative mesorectal fascia.

CONCLUSIONS

A cutoff of 7 mm of the distance between the deepest tumor invasion and mesorectal fascia on baseline MRI can distinguish cT3 rectal cancer from a different prognosis. We recommend using the distance between the deepest tumor invasion and mesorectal fascia on baseline MRI for local and systemic risk assessment and providing a tailored schedule of neoadjuvant treatment. See Video Abstract at http://links.lww.com/DCR/B682.CORRELACIÓN ENTRE LA DISTANCIA DE LA FASCIA MESORRECTAL Y EL PRONÓSTICO DEL CÁNCER DE RECTO cT3: RESULTADOS DE UN ESTUDIO MULTICÉNTRICO DE CHINAANTECEDENTES:Los criterios de subestadificación cT3 basados en la profundidad extramural de invasión tumoral en el cáncer de recto tienen varias limitaciones.OBJETIVO:Este estudio propuso que la distancia entre la invasión tumoral más profunda y la fascia mesorrectal en la resonancia magnética preterapia puede distinguir el pronóstico de los pacientes con cT3.DISEÑO:Estudio de cohorte.ENTORNO CLINICO:El estudio incluyó una cohorte observacional, prospectiva, unicéntrica, y una cohorte de validación retrospectiva, multicéntrica e independiente.PACIENTE:Se incluyeron pacientes con cáncer de recto cT3 con fascia mesorrectal negativa sometidos a quimio-radioterapia neoadyuvante seguida de cirugía radical en cuatro centros de China desde enero de 2013 hasta septiembre de 2014.INTERVENCIÓN:Imágenes de resonancia magnética de referencia fueron medidas con la distancia entre la invasión tumoral más profunda y la fascia mesorrectal; la profundidad extramural de la invasión tumoral y el grosor del mesorrecto.PRINCIPALES MEDIDAS DE VALORACION:El límite de la distancia entre la invasión tumoral más profunda y la fascia mesorrectal se determinó mediante curvas características operativas del receptor dependientes del tiempo y se apoyó en la tasa de progresión a 5 años de la cohorte prospectiva, y luego se validó en una cohorte retrospectiva.RESULTADOS:Se incluyeron 124 y 274 pacientes en la cohorte de validación prospectiva e independiente, respectivamente. La distancia entre la invasión tumoral más profunda de la fascia mesorrectal fue el único predictor de muerte específica por cáncer (Hazard ratio: 0.1, 95% CI, 0,0-0,7); y también fue un predictor significativo de recurrencia distante Hazard ratio: 0,4, 95% CI, 0,2-0,9). No se observaron diferencias estadísticamente significativas en el pronóstico entre los pacientes clasificados como T3a/b y T3c/d.LIMITACIONES:El tamaño de la muestra es relativamente pequeño y el estudio se centró en los cánceres de recto cT3 con fascia mesorrectal negativa.CONCLUSIONES:Un límite de 7 mm de distancia entre la invasión tumoral más profunda y la fascia mesorrectal en la resonancia magnética de referencia puede distinguir el cáncer de recto cT3 de diferentes pronósticos. Recomendamos la distancia entre la invasión tumoral más profunda y la fascia mesorrectal en la resonancia magnética de referencia para la evaluación del riesgo local y sistémico, proporcionando un programa personalizado de tratamiento neoadyuvante. Consulte Video Resumen en http://links.lww.com/DCR/B682. (Traducción- Dr. Francisco M. Abarca-Rendon).

Prognostic significance of pathological sub-classification of pT3 rectal cancer

PURPOSE

Patients with pT3 rectal cancer represent a heterogeneous prognostic group. A more accurate histological sub-classification of pT status has been suggested as an improvement of the TNM staging system. The aim of the study was to evaluate the prognostic implication of a histopathologic sub-classification of pT3 rectal cancer.

METHODS

In this retrospective single-center study, pT3 rectal cancer patients who underwent surgery from January 2000 to December 2018 were evaluated. The maximum depth of tumor invasion beyond the muscularis propria was recorded. A ROC curve identified the best prognostic cutoff value to classify patients in two prognostic groups. Survival curves were estimated by the Kaplan-Meier method, and univariate and multivariate analyses with the Cox regression model were used to find independent factors influencing survival.

RESULTS

Overall, 203 patients were included. Four millimeters was identified as the best cutoff value: 82 patients showed a depth of invasion < 4 mm (group A) and 121 ≥ 4 mm (group B). Both the estimated 5-year OS and DFS were statistically better in group A than in group B (OS: 83.9% vs 62.2%, p < 0.01; DFS: 78.3% vs 40.6%, p < 0.01). The depth of tumor invasion was an independent risk factor for OS (HR 2.25, 95% CI 1.26-3.99, p = 0.006) and DFS (HR 2.30, 95% CI 1.40-3.78, p = 0.001).

CONCLUSION

Our findings suggest that a sub-classification of pT3 rectal cancer, based on the depth of tumor invasion, should be considered to be introduced in the TNM staging system.

Better prognostic determination of cT3 rectal cancer through measurement of distance to mesorectal fascia: A multicenter study

Objective

To forward the magnetic resonance imaging (MRI) based distance between the deepest tumor invasion and mesorectal fascia (DMRF), and to explore its prognosis differentiation value in cT3 stage rectal cancer with comparison of cT3 substage.

Methods

This was a retrospective, multicenter cohort study including cT3 rectal cancer patients undergoing neoadjuvant chemoradiotherapy followed by radical surgery from January 2013 to September 2014. DMRF and cT3 substage were evaluated from baseline MRI. The cutoff of DMRF was determined by disease progression. Multivariate cox regression was used to test the prognostic values of baseline variables.

Results

A total of 804 patients were included, of which 226 (28.1%) developed progression. A DMRF cutoff of 7 mm was chosen. DMRF category, the clock position of the deepest position of tumor invasion (CDTI) and extramural venous invasion (EMVI) were independent predictors for disease progression, and hazard ratios (HRs) were 0.26 [95% confidence interval (95% CI), 0.13−0.56], 1.88 (95% CI, 1.33−2.65) and 1.57 (95% CI, 1.13−2.18), respectively. cT3 substage was not a predictor for disease progression.

Conclusions

The measurement of DMRF value on baseline MRI can better distinguish cT3 rectal cancer prognosis rather than cT3 substage, and was recommended in clinical evaluation.

Morphometric assessment of the mesorectal fat in Chinese Han population: A clinical MRI study

The study aimed to analyze morphometric assessment of the mesorectal fat thickness and its correlation with body mass index in Chinese Han population. The anterior, posterior, right lateral, and left lateral mesorectal fat thickness were measured using MRI T2-weighted images. The mean distance from the rectal wall to the mesorectal fascia were 3.8, 8.4, 11.3, and 11.7 mm in anterior, posterior, right lateral, and left lateral portion, respectively. The mesorectal area, rectal area, mesorectal fat thickness area, and rectal height were 2395.3 ± 691.1 mm2, 709.6 ± 403.5 mm2, 1685.7 ± 525.3 mm2, and 9.1 ± 0.8 cm. BMI was found to be directly proportional to and statistically significant to the mesorectal fat area (p = 0.01). Since the mean mesorectal fat thickness was found to be <12 mm, T3d staged rectal cancer is less likely to be found in an average Chinese population that may affect the overall-survival and progression-free survival in rectal cancer patients. Anterior portion of the rectum was least thick compared to all other sides. Therefore, extra-caution should be taken in handling tumors on the anterior part of the rectum.

Does the depth of mesorectal invasion have prognostic significance in patients with ypT3 lower rectal cancer treated with preoperative chemoradiotherapy?

PURPOSE

The prognostic significance of the depth of mesorectal invasion (DMI) in patients with ypT3 rectal cancer who undergo preoperative chemoradiotherapy (CRT) is unclear. The purpose of this study was to evaluate the prognostic significance of DMI in ypT3 rectal cancer.

METHODS

A total of 168 (y)pT3 patients were evaluated, of whom 93 received preoperative CRT and 75 underwent surgery alone. Patients were subdivided into two groups according to the DMI (T3ab = DMI ≤5 mm and T3cd = DMI >5 mm). Oncologic outcomes were compared between the T3ab and T3cd groups and the ypT3ab and ypT3cd groups.

RESULTS

Relapse-free survival was significantly different between the pT3ab and pT3cd groups (74.1 vs 38.5%, P = 0.0192) but not between the ypT3ab and ypT3cd groups (65.9 vs 61.5%, P = 0.513). Multivariate analysis showed that DMI was an independent predictor of recurrence in pT3 patients (hazard ratio [HR] = 2.980, 95% confidence interval [CI] 1.227-7.025; P = 0.0169) and that ypN+ was an independent predictor of recurrence in ypT3 patients (HR = 3.487, 95% CI 1.570-8.827; P = 0.0016).

CONCLUSIONS

DMI was not a significant predictive factor for recurrence in patients with ypT3 rectal cancer who underwent preoperative CRT, and ypN+ was the only independent predictive factor for recurrence.

The degree of extramural spread of T3 rectal cancer: an appeal to the American Joint Committee on Cancer

The T3 category of the TNM classification includes over 60% of all rectal tumours and encompasses the greatest variance in cancer-specific end-points than any other T category. The most recent edition of the cancer staging handbook of the American Joint Committee on Cancer (AJCC) dated 2010 does not divide T3 tumours into subgroups which reflect cancer-specific outcome more sensitively. The original aim of the present study was to review the literature to assess the influence of the degree of extramural extent of T3 rectal cancer on local recurrence and survival. An article written by the authors was accepted for publication but was withdrawn immediately after they became aware of the publication of the 4th edition of the TNM Supplement by the Union for International Cancer Control dated 2012, which was not accessible by the search system used. This article dealt with the subdivision of the T3 category although this was not included in the most up-to-date AJCC guidelines and was stated to be 'entirely optional'. Medline, PubMed and Cochrane Library searches were performed to identify all studies that investigated the degree of extramural spread and its relationship to survival and local recurrence. Twenty-two studies were identified of which 12 assessed the degree of histopathological extramural spread measured in millimetres. In 18 of the 22 studies the degree of extramural spread was a statistically significant prognostic factor for survival and local recurrence. Analysis of the studies indicated that the subdivision of category T3 rectal cancer into two subgroups of extramural spread ≤ 5 mm or more than 5 mm resulted in markedly different survival and local recurrence rates. The data were insufficient to allow validation of any greater subdivision. Measurement of the extent of extramural spread by MRI before any treatment agreed with the histopathological measurement in the surgical specimen to within 1 mm. The extent of extramural spread in T3 rectal cancer measured in millimetres is a powerful prognostic factor. A subdivision of T3 into T3a and T3b of less than or equal to or more than 5 mm appears to give the greatest discrimination of local recurrence and survival. Preoperative T3 subdivision by MRI has the same sensitivity as histopathological examination of the resected specimen. Given the clinical need for the pretreatment classification of the T3 category for oncological management planning, the evidence strongly indicates that the subdivision of the T3 category by MRI should be formally considered as part of the TNM staging system for rectal cancer.

Prognostic stratification by extramural depth of tumor invasion of primary rectal cancer based on the Radiological Society of North America proposal

OBJECTIVE

The purpose of this study was to investigate the diagnostic performance of MRI in stratifying tumors stage III (T3) in patients with rectal cancer by measuring the extramural depth of tumor invasion based on the Radiologic Society of North America (RSNA) proposal and to validate its role as a prognostic indicator.

MATERIALS AND METHODS

From January 2006 to July 2009, 146 patients with surgically and pathologically confirmed T3 rectal adenocarcinoma who underwent preoperative MRI were enrolled. Two blinded radiologists measured the maximum extramural depth of tumor invasion on T2-weighted images. To evaluate the diagnostic performance of MRI for stratifying subgroups, the study population was assigned into three subgroups (T3a, T3b, and T3c) according to extramural depth of tumor invasion (< 5, 5-10, and > 10 mm).To validate the role of extramural depth of tumor invasion as a prognostic indicator, Cox regression analysis was used for estimation of independent risk factors for postoperative recurrence. Three-year recurrence-free survival was evaluated by the Kaplan-Meier method with a log-rank test. Histopathologic reports were used as the reference standard.

RESULTS

The overall accuracy of MRI for stratifying subgroups was 71.2% (104/146) and 77.4% (113/146) for reviewers 1 and 2. Extramural depth of tumor invasion was an independent risk factor for 3-year recurrence-free survival (hazard ratio, 2.186; 95% CI, 1.336-3.577; p = 0.002). Kaplan-Meier curves revealed a significant difference in 3-year recurrence-free survival rates for each subgroup (86%, 69%, and 43% for T3a, T3b, and T3c; p < 0.03).

CONCLUSION

MRI can be used for prognostic stratification according to extramural depth of tumor invasion based on the RSNA proposal for patients with T3 rectal cancer.

Prognostic subdivision of ypT3 rectal tumours according to extension beyond the muscularis propria

Background

The subdivision of T3 in rectal carcinoma according to the depth of invasion into perirectal fat has been recommended in the TNM Supplement since 1993. This study assessed the prognostic impact of this pathological staging in tumours removed after neoadjuvant chemoradiotherapy (ypT3).

Methods

Data from patients with ypT3 rectal carcinoma (less than 12 cm from the anal verge) treated with neoadjuvant chemoradiation and total mesorectal excision were analysed. Tumour category ypT3 was subdivided into ypT3a (5 mm or less) and ypT3b (more than 5 mm), based on histological measurements of maximal tumour invasion beyond the outer border of the muscularis propria.

Results

Important differences between ypT3a (81 patients) and ypT3b (43) were found in 5-year rates of locoregional recurrence (7 versus 18 per cent; P = 0·049), distant metastasis (20 versus 41 per cent; P = 0·002), disease-free survival (73 versus 47 per cent; P = 0·001), overall survival (79 versus 74 per cent; P = 0·036) and cancer-related survival (81 versus 74 per cent; P = 0·007). In Cox regression analyses, the ypT3 subclassification was identified as an independent prognostic factor for disease-free (ypT3b: hazard ratio (HR) 2·13, 95 per cent confidence interval 1·16 to 3·89; P = 0·014), observed (ypT3b: HR 2·02, 1·05 to 3·87; P = 0·035) and cancer-related (ypT3b: HR 2·46, 1·20 to 5·04; P = 0·014) survival. Extramural venous invasion was found to be an additional prognostic factor, but the pathological node category after chemoradiotherapy (ypN) did not influence survival.

Conclusion

In ypT3 rectal carcinomas, the proposed subclassification is superior to ypN in predicting prognosis.

Distal dissection in total mesorectal excision, and preoperative chemoradiotherapy and lateral lymph node dissection for rectal cancer

The local recurrence rate after total mesorectal excision (TME) appears to be markedly lower than that after conventional operations. We reviewed all relevant articles identified from the MEDLINE databases and clarified the rationale for TME. It is clear that distal intramural spread is rare. Even when present, such spread is not likely to extend beyond 2 cm. Data with attention to mesorectal cancer deposits suggest that mesorectal clearance of at least 4-5 cm distal to the tumor should be sufficient. TME should be performed for most tumors of the mid- and lower rectum. This does not mean that the gut tube needs to be divided at the same level in every case. Dissection of the distal mesorectum off the gut tube can be performed, so the distal line of division of the bowel wall can be made at a minimum of 2 cm below the tumor if such a maneuver would ensure that the sphincters are preserved. In cases with cancer in the upper third of the rectum, the mesorectum and gut tube can safely be divided 5 cm below the tumor without jeopardizing the recurrence rates. Our findings indicate that TME is an essential treatment approach for rectal cancer, and lateral lymph node dissection and preoperative chemoradiotherapy are additional therapies that should be considered for advanced rectal cancer.

Challenges in the neoadjuvant treatment of rectal cancer: balancing the risk of recurrence and quality of life

The management of patients with rectal cancer has improved substantially-assisted by refinements in surgical technique, the increasing accuracy of preoperative imaging, more precise delivery of radiotherapy¸and more informative feedback from the histopathologist. Multidisciplinary teams have been the key to this success. Future challenges facing multidisciplinary teams include individually tailoring therapy - in particular in deciding who does and does not need radiotherapy, utilising new radiotherapy techniques such as intensity-modulated radiotherapy and image-guided radiotherapy and new systemic therapies, and electing patients for whom chemoradiotherapy might be potentially curative without surgical resection after complete clinical response. Hence, there is an increasing focus on developing predictive and prognostic molecular biomarkers. This paper explores the background to common variations in practice, and the current and future challenges in the neoadjuvant treatment of rectal cancer.

Extramural extension as indicator for postoperative adjuvant chemotherapy in Stage IIA (pT3N0) colon cancer

The usefulness of adjuvant chemotherapy (CMT) in patients with Stage IIA colon cancer remains unclear. The present study aimed to investigate extramural extension as an indicator for adjuvant CMT. Data were reviewed from 202 consecutive patients with Stage IIA colon cancer that underwent curative surgery between 1995 and 2007. The distance of the extramural extension (DEE) was measured histologically. The optimal prognostic cut-off point of the DEE for oncologic outcomes was statistically determined. The eligible surviving patients had been followed for a median period of 75 months (range: 2-210 months). Patients were subdivided into two groups according to the optimal cut-off point; DEE ≤5 mm (pT3a) and DEE >5 mm (pT3b). The pT3b was the most powerful independent risk factor for postoperative recurrence (P = 0.0324, HR: 3.04, 95% CI: 1.098-8.408), and was significantly correlated with distant metastasis (P = 0.0161 HR: 5.19, 95% CI: 1.765-15.239). The recurrence-free and cancer-specific 5-year survival rates in patients with pT3b were significantly lower than in patients with pT3a (81.5% vs. 95.4%, P = 0.0003 and 85.9% vs. 97.4%, P = 0.0007, respectively). pT3b could be an important risk factor for distant metastasis in Stage IIA colon cancer. Postoperative adjuvant CMT may be indicated for patients with pT3b.