• cancer-see oncology
• chemotherapy
• colon cancer
• pregnancy

• Pregnancy
• Child
• Humans
• Male
• Female
• Antineoplastic Combined Chemotherapy Protocols/therapeutic use
• Rectal Neoplasms/pathology
• Carcinoma, Squamous Cell/pathology
• Fluorouracil/therapeutic use
• Treatment Outcome
• Cisplatin/therapeutic use

• adult intussusception
• colon resection
• colonic adenocarcinoma
• gastrointestinal neuroendocrine tumor
• ileo-colic intussusception
• large cell neuroendocrine
• large-cell neuroendocrine carcinoma
• right hemicolectomy

• adjuvant chemotherapy
• case report
• colorectal cancer
• immune checkpoint inhibitors
• microsatellite instability
• squamous cell carcinoma

• carcinoma
• metastasectomy
• neuroendocrine
• operative therapy
• survival analysis

• Humans
• United States/epidemiology
• Retrospective Studies
• Pancreatic Neoplasms/surgery
• Pancreatic Neoplasms/pathology
• Carcinoma, Neuroendocrine/surgery
• Carcinoma, Neuroendocrine/pathology
• Neuroendocrine Tumors/surgery
• Neuroendocrine Tumors/pathology
• Prognosis

• Adult rare cancer
• Cancer rare chez l’adulte
• Cancers rares gastro-intestinaux
• Gastrointestinal rare cancers
• Radiotherapy
• Radiothérapie

• Adult
• Humans
• Gastrointestinal Neoplasms/radiotherapy
• Carcinoma, Squamous Cell/radiotherapy
• Chemoradiotherapy, Adjuvant
• Esophageal Neoplasms/therapy
• Chemoradiotherapy
• Neoadjuvant Therapy
• Adenocarcinoma/drug therapy

• SEER (surveillance epidemiology and end results) database
• chemoradiotherapy (CRT)
• prognosis
• rectal cancer (RC)
• squamous cell carcinoma

Rectal neuroendocrine tumours represent a rare colorectal tumour with a 10 fold increased prevalence due to incidental detection in the era of colorectal screening. Patient outcomes with early diagnosis are excellent. However endoscopic recognition of this lesion is variable and misdiagnosis can result in suboptimal endoscopic resection with subsequent uncertainty in relation to optimal long-term management. Endoscopic techniques have shown particular utility in managing this under-recognized neuroendocrine tumour.

• Rectal neuroendocrine tumour
• Carcinoid
• Endoscopic mucosal resection
• Endoscopic submucosal dissection
• Knife-assisted snare resection

• Anal squamous cell carcinoma
• Human Papilloma Virus
• Next-generation sequencing 
• Rectal adenocarcinoma
• Rectal squamous cell carcinoma

• radiotherapy
• rectal cancer
• squamous cell carcinoma

The pathological type of simple squamous carcinoma in colorectal malignancies is rare. Simple squamous cell carcinoma of the colorectum occurs most frequently in the rectum. The clinicopathological features and biological behaviors of squamous colorectal carcinoma are unclear, and its prognosis may be worse than that of simple adenocarcinoma. Studies on squamous colorectal cancer are currently limited to case reports, and there is no standard treatment protocol. Therefore, more case reports are required to fully understand squamous colorectal cancer.

We reported the case of a 56-year-old woman who complained of constipation for 2 years. Colonoscopy revealed a sigmoid colon tumor, and the pathological result of colonoscopy was squamous carcinoma. After completing the relevant assessment, the patient was clinically diagnosed with cT4aN0M0, stage IIB, and surgery was performed. Based on postoperative pathological results, the patient was diagnosed with pT4bN0M0, stage IIC. Six cycles of adjuvant chemotherapy were administered after surgery. Liver metastasis and abdominal wall mass were found more than 1 mo after the end of the last chemotherapy session. Targeted local treatment was not performed because the liver had multiple metastases, but I¹²⁵ particle implantation of the abdominal wall mass was performed. Two cycles of first-line chemotherapy were administered after the surgery. The patient underwent 14 mo of treatment and eventually died from the tumor.

Squamous carcinoma of sigmoid colon is a rare tumor with unclear pathogenesis. Its clinicopathological diagnosis should be paid close attention.

• Colon malignancies
• Sigmoid colon
• Squamous carcinoma
• Liver metastases
• Case report

• Chemotherapy
• Colon cancer
• Malignant and Benign haematology
• Oncology

• Adenocarcinoma/diagnosis
• Adenocarcinoma/drug therapy
• Adenocarcinoma/surgery
• Aged
• Antineoplastic Combined Chemotherapy Protocols/therapeutic use
• Colonic Neoplasms/drug therapy
• Colonic Neoplasms/pathology
• Colonic Neoplasms/surgery
• Cyclophosphamide/therapeutic use
• Doxorubicin/therapeutic use
• Humans
• Lymphoma/drug therapy
• Lymphoma, B-Cell/drug therapy
• Male
• Prednisone/therapeutic use
• Vincristine/therapeutic use

Colon medullary adenocarcinoma (MAC) is a rare histologic subtype. Clinical presentation and cancer outcomes of MAC, compared to colon adenocarcinoma (AC), remain incompletely described. Annual age-adjusted incidence rates were computed using Surveillance, Epidemiology, and End Results (2002–2017). A cohort analysis using the National Cancer Database (2010–2016) compared patient characteristics in an unmatched dataset and prognostic characteristics in a 1:1 matched subset. Reported annual age-adjusted incidence of MAC has significantly increased, with an average annual percent change (APC) increase of 23.8% (95% CI: 19.2–28.6); concurrent AC incidence declined (APC: − 2.8, 95% CI: − 3.1 to − 2.8). Analyses of 1018 MAC and 210,784 AC unmatched patients showed that MAC patients were more often older, female, and white, with higher disease stage, poorly-differentiated tumors, right-sided laterality, and lymphovascular invasion (all p < 0.0001). Among those with known microsatellite status, instability was more prevalent among MAC than AC patients (82% vs. 24%, p < 0.0001). Multivariate analyses of the matched dataset revealed that MAC histology was not independently associated with overall survival. However, when stratifying by laterality, left-sided MAC was associated with shorter survival when compared to right-sided MAC (HR 1.66, 95% CI 1.16–2.38) and right-sided AC (HR 1.54, 95% CI 1.12–2.12). The reported incidence of MAC is increasing, in contrast to the declining incidence of AC. MAC clinical and molecular features are distinct from AC and likely account for outcome differences. Overall, left-sided MAC was associated with the shortest OS. Molecular profiling may improve treatment guidelines for MAC.

• Histology
• Incidence
• Population-based study
• Rare cancer
• Rectal cancer

Squamous cell carcinoma of the rectum is a rare malignancy (0.3% of all rectal cancers), with no known risk factor. These tumours are assessed as rectal cancer using immunohistochemical and radiological tests, and certain criteria (localisation, relationship with neighbouring structures) have to be fulfilled to make the diagnosis. Some clinicians used to stage them with the anal cancer TNM (tumour–node–metastasis), whereas others used the rectal cancer TNM. When localised, the tendency nowadays is to treat those tumours like squamous anal cancers with definitive chemoradiotherapy (5-fluorouracil and mitomycin) and to skip surgery. For metastatic disease there is no clearly validated regimen and treatment should be based on recommendations of squamous anal cancers because of their common histology. Concerning follow-up after a curative approach, techniques should follow those for anal cancer as well, evaluating a delayed response.

•

Rectal squamous cell carcinoma (rSCC) is a rare entity for which we have limited knowledge and no clear recommendations.

• definitive chemoradiotherapy
• rare disease
• squamous rectal cancer

• extrapulmonary
• neuroendocrine carcinoma
• phase II study
• poorly differentiated
• temozolomide

• Adult
• Aged
• Antineoplastic Agents, Alkylating/administration & dosage
• Antineoplastic Agents, Alkylating/adverse effects
• Antineoplastic Agents, Alkylating/therapeutic use
• Antineoplastic Combined Chemotherapy Protocols/therapeutic use
• Carcinoma, Neuroendocrine/drug therapy
• Carcinoma, Neuroendocrine/enzymology
• Carcinoma, Neuroendocrine/mortality
• Carcinoma, Neuroendocrine/pathology
• Colonic Neoplasms/drug therapy
• Colonic Neoplasms/enzymology
• Colonic Neoplasms/pathology
• Drug Administration Schedule
• Duodenal Neoplasms/drug therapy
• Duodenal Neoplasms/enzymology
• Duodenal Neoplasms/pathology
• Female
• Gallbladder Neoplasms/drug therapy
• Gallbladder Neoplasms/enzymology
• Gallbladder Neoplasms/pathology
• Humans
• Ki-67 Antigen/analysis
• Liver Neoplasms/drug therapy
• Liver Neoplasms/enzymology
• Liver Neoplasms/pathology
• Male
• Middle Aged
• O(6)-Methylguanine-DNA Methyltransferase/analysis
• Pancreatic Neoplasms/drug therapy
• Pancreatic Neoplasms/enzymology
• Pancreatic Neoplasms/pathology
• Progression-Free Survival
• Prospective Studies
• Stomach Neoplasms/drug therapy
• Stomach Neoplasms/enzymology
• Stomach Neoplasms/pathology
• Temozolomide/administration & dosage
• Temozolomide/adverse effects
• Temozolomide/therapeutic use
• Uterine Neoplasms/drug therapy
• Uterine Neoplasms/enzymology
• Uterine Neoplasms/pathology

• Yokohama City University

• Analytical methods
• Carcinoid syndrome
• Neuroendocrine neoplasm
• Serotonin pathway
• Telotristat

• Humans
• Malignant Carcinoid Syndrome/diagnosis
• Malignant Carcinoid Syndrome/drug therapy
• Malignant Carcinoid Syndrome/metabolism
• Malignant Carcinoid Syndrome/physiopathology
• Phenylalanine/analogs & derivatives
• Phenylalanine/therapeutic use
• Pyrimidines/therapeutic use
• Serotonin/metabolism
• Signal Transduction/drug effects
• Tryptophan Hydroxylase/antagonists & inhibitors

• Brain metastasis
• Chemotherapy
• Pancreatobiliary neuroendocrine carcinoma
• Radiation therapy
• Surgical resection

Squamous cell carcinoma (SCC) is most commonly seen in the esophagus and anal canal in the gastrointestinal tract. The incidence of SCC of the rectum is infrequent with no clear etiology. There have been limited reported cases of SCC of the rectum caused by human papillomavirus (HPV). Due to the rarity of carcinoma, the management of SCC of the rectum is not standardized. We report a case of a 51-year-old female with an insignificant medical history presenting with hematochezia and weight loss and was found to have HPV-positive SCC of the rectum. This case report emphasizes the importance of work-up, usefulness of HPV testing for high-risk patients, and clinical management of SCC of the rectum.

• human papillomavirus (hpv)
• rectal carcinoma
• squamous cell carcinoma

• Ki-67
• Poorly differentiated neuroendocrine carcinoma
• WHO classification and grade
• Well-differentiated neuroendocrine tumor

• Clinicopathologic features
• Colorectal neuroendocrine neoplasms
• Distance from anal verge
• Lymphatic metastasis
• Prognosis

• Humans
• Lymphatic Metastasis
• Neoplasm Staging
• Neuroendocrine Tumors/pathology
• Prognosis
• Rectal Neoplasms/pathology
• Retrospective Studies
• Risk Factors

• Bevacizumab
• Chemotherapy
• Everolimus
• Immunotherapy
• Targeted therapy

• nomogram
• overall survival
• prognosis
• rectal squamous cell carcinomas

• Adult
• Age Factors
• Aged
• Aged, 80 and over
• Antineoplastic Agents/therapeutic use
• Carcinoma, Squamous Cell/mortality
• Carcinoma, Squamous Cell/pathology
• Carcinoma, Squamous Cell/therapy
• Female
• Humans
• Kaplan-Meier Estimate
• Male
• Middle Aged
• Multivariate Analysis
• Neoplasm Staging
• Nomograms
• Proctectomy/methods
• Prognosis
• Proportional Hazards Models
• ROC Curve
• Radiotherapy/methods
• Rectal Neoplasms/mortality
• Rectal Neoplasms/pathology
• Rectal Neoplasms/therapy
• SEER Program
• Sex Factors
• Socioeconomic Factors
• Tumor Burden
• United States
• Young Adult

Neuroendocrine tumors (NETs) are heterogeneous, widely distributed tumors arising from neuroendocrine cells. Gastrointestinal (GI)-NETs are the most common and NETs of the rectum represent 15, 2% of gastrointestinal malignancies. Poorly differentiated neuroendocrine carcinomas of the GI tract are uncommon. We report a rare case of poorly differentiated locally advanced rectal neuroendocrine carcinoma with nodal and a subcutaneous metastasis, with a cytoplasmic staining positive for Synaptophysin and Thyroid Transcription Factor-1.

A 72-year-old male presented to hospital, due to lumbar, abdominal, perineal pain, and severe constipation. A whole-body computed tomography scan showed a mass of the right lateral wall of the rectum, determining significant reduction of lumen caliber. It also showed a subcutaneous metastasis of the posterior abdominal wall. Patient underwent a multidisciplinary evaluation, diagnostic and therapeutic plan was shared and defined. The pathological examination of rectal biopsy and subcutaneous nodule revealed features consistent with small-cell poorly differentiated neuroendocrine carcinoma. First line medical treatment with triplet chemotherapy and bevacizumab, according to FIr-B/FOx intensive regimen, administered for the first time in this young elderly patient affected by metastatic rectal NEC was highly active and tolerable, as previously reported in metastatic colo-rectal carcinoma (MCRC). A consistent rapid improvement in clinical conditions were observed during treatment. After 6 cycles of treatment, CT scan and endoscopic evaluation showed clinical complete response of rectal mass and lymph nodes; patient underwent curative surgery confirming the pathologic complete response at PFS 9 months.

This case report of a locally advanced rectal NEC with an unusual subcutaneous metastasis deserves further investigation of triplet chemotherapy-based intensive regimens in metastatic GEP NEC.

• FIr-B/FOx
• NEC
• Neuroendocrine carcinoma
• Subcutaneous metastasis
• Thyroid transcription factor-1
• Triplet chemotherapy plus bevacizumab

Colorectal high-grade neuroendocrine neoplasms (HGNENs) are rare and constitute less than 1% of all colorectal malignancies. Based on their morphological differentiation and proliferation identity, these neoplasms present heterogeneous clinicopathologic features. Opinions regarding treatment strategies for and improvement of the clinical outcomes of these patients remain controversial.

To delineate the clinicopathologic features of and explore the prognostic factors for this rare malignancy.

This observational study reviewed the data of 72 consecutive patients with colorectal HGNENs from three Chinese hospitals between 2000 and 2019. The clinicopathologic characteristics and follow-up data were carefully collected from their medical records, outpatient reexaminations, and telephone interviews. A survival analysis was conducted to evaluate their outcomes and to identify the prognostic factors for this disease.

According to the latest recommendations for the classification and nomenclature of colorectal HGNENs, 61 (84.7%) patients in our cohort had poorly differentiated neoplasms, which were categorized as high-grade neuroendocrine carcinomas (HGNECs), and the remaining 11 (15.3%) patients had well differentiated neoplasms, which were categorized as high-grade neuroendocrine tumors (HGNETs). Most of the neoplasms (63.9%) were located at the rectum. More than half of the patients (51.4%) presented with distant metastasis at the date of diagnosis. All patients were followed for a median duration of 15.5 mo. In the entire cohort, the median survival time was 31 mo, and the 3-year and 5-year survival rates were 44.3% and 36.3%, respectively. Both the univariate and multivariate analyses demonstrated that increasing age, HGNEC type, and distant metastasis were risk factors for poor clinical outcomes.

Colorectal HGNENs are rare and aggressive malignancies with poor clinical outcomes. However, patients with younger age, good morphological differentiation, and without metastatic disease can have a relatively favorable prognosis.

• Colon
• Rectum
• Neuroendocrine
• Neoplasm
• Metastasis
• Prognosis

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Carcinoma, Neuroendocrine/epidemiology
• Carcinoma, Neuroendocrine/pathology
• China/epidemiology
• Colorectal Neoplasms/epidemiology
• Colorectal Neoplasms/pathology
• Female
• Follow-Up Studies
• Humans
• Incidence
• Kaplan-Meier Estimate
• Male
• Middle Aged
• Neoplasm Grading
• Prognosis
• Prospective Studies
• Survival Rate
• Time Factors
• Young Adult

• Diagnostic accuracy
• Imaging modality
• Lymph node involvement
• Overview
• Rectal cancer

Leverage the National Cancer Database (NCDB) to evaluate trends in management of nonmetastatic squamous cell cancer (SCC) of the rectum and their effect on survival for this uncommon tumor.

Retrospective data was obtained from the NCDB for patients diagnosed with SCC of the rectum between 2004 and 2014, including cT1‐4, cN0‐2, cM0 tumors (cohort A, n = 2296). A subgroup analysis was performed on locally advanced tumors (cT1‐T2, N+ or cT3, N any, subcohort B, n = 883), treated with chemoradiation (n = 706) or trimodality therapy (n = 177) including chemotherapy, radiation, and surgery. Pathological complete response rate following neoadjuvant therapy was obtained. Univariate and multivariate logistic regression analyses were performed to generate hazard ratios (HR) investigating factors associated with overall survival. Kaplan‐Meier (K‐M) method was used to estimate overall surviving proportion at 5 and 10 years.

The K‐M estimated 5 and 10 year overall survival for stage I disease was 71.3% and 57.8%, respectively; stage II disease was 57.0% and 38.9%, respectively; stage III disease was 57.8% and 41.5%, respectively. On multivariate analysis, higher cT category (P < 0.001) resulted in worse survival. For locally advanced tumors (subcohort B), there was no significant difference in survival between chemoradiation alone compared to trimodality therapy (P = 0.909 on multivariate analysis).

Most providers manage locally advanced SCC of the rectum similar to anal cancer, which results in equivalent overall survival and spares patients from the additional morbidity associated with surgical resection.

• National Cancer Database
• cancer
• chemoradiation
• radiation
• rectal
• squamous

Colorectal large-cell neuroendocrine carcinomas (NECs) are extremely rare and have very poor prognosis compared to adenocarcinomas. A 74-year-old man presented with abdominal pain, diarrhea and hematochezia. The histopathologic report of colonoscopic biopsy performed at a local clinic was a poorly differentiated carcinoma. An abdominopelvic computed scan revealed irregularly enhanced wall thickening at the sigmoid colon with regional fat stranding and lymphnode enlargement. He underwent a laparoscopic high anterior resection with selective peritonectomy for peritoneal carcinomatosis, intraoperative peritoneal irrigation chemotherapy, and early postoperative intraperitoneal chemotherapy for 5 days. The tumor had a high proliferation rate (mitotic count > 50/10 HPFs and 90% of the Ki-67 index) and lymph-node metastases had occurred. On immunohistochemistry, the tumor cells expressed CD56 and synaptophysin. Large-cell NEC was confirmed. Systemic chemotherapy with cisplatin/etoposide was done. The patient is still alive after 3 years with no evidence of recurrence.

• Colon
• Large-cell neuroendocrine carcinoma
• Peritoneal carcinomatosis

• Endoscopic resection
• Neuroendocrine neoplasms of rectum
• Prognostic factors
• Surgery
• Survival

• Humans
• Male
• Neuroendocrine Tumors/mortality
• Neuroendocrine Tumors/pathology
• Neuroendocrine Tumors/surgery
• Neuroendocrine Tumors/therapy
• Prognosis
• Rectal Neoplasms/mortality
• Rectal Neoplasms/pathology
• Rectal Neoplasms/surgery
• Rectal Neoplasms/therapy
• Survival Analysis

Only a few case reports to date have described patients with three or more cancers. However, the incidence of multiple primary malignancies is increasing due to the improved survival of cancer patients, the prolonged lifespan of the general population, and better diagnostic techniques. This report describes a 73-year-old woman with primary breast, rectal squamous cell, and renal cell carcinomas. This case is unique because, in addition to having three primary malignancies, this patient had rectal squamous cell carcinoma—one of the rarest types of rectal cancer. We discuss screening and prevention of multiple malignancies and rectal squamous cell carcinoma, as well as methods for managing these patients.

• breast cancer
• multiple primary malignant neoplasms
• rectal squamous cell carcinoma
• renal cell carcinoma
• triple malignancy

Accurate staging is crucial for treatment selection and prognosis prediction in patients with rectal cancer. Point spread function (PSF) reconstruction can improve spatial resolution and signal-to-noise ratio of PET imaging. The aim of this study was to evaluate the effectiveness of ¹⁸F-FDG PET/CT with PSF reconstruction for initial staging in rectal cancer compared with conventional PET/CT and pelvic MRI.

A total of 59 patients with rectal cancer underwent preoperative ¹⁸F-FDG PET/CT and pelvic MRI. The maximum standardized uptake value (SUVmax) and lesion to background (L/B) ratio of possible metastatic lymph nodes, and metabolic tumor volumes (MTVs) of primary tumors were calculated. For N and T (T1-2 vs T3-4) staging, sensitivities, specificities, positive predictive values, negative predictive values, and accuracies were compared between conventional PET/CT [reconstructed with ordered subset expectation maximization (OSEM)], PSF-PET/CT (reconstructed with OSEM+PSF), and pelvic MRI. Histopathologic analysis was the reference standard.

For N staging, PSF-PET/CT provided higher sensitivity (78.6%) than conventional PET/CT (64.3%), and pelvic MRI (57.1%), and all techniques showed high specificity (PSF-PET: 95.4%, conventional PET: 96.7%, pelvic MRI: 93.5%). SUVmax and L/B ratio were significantly higher in PSF-PET/CT than conventional-PET/CT (p < 0.001). The accuracy for T staging in PSF-PET/CT (69.4%) was not significantly different to conventional PET/CT (73.5%) and pelvic MRI (73.5%). MTVs of PSF and conventional PET showed a significant difference among T stages (p < 0.001), with higher values in advanced stages. In M staging, both PSF and conventional PET/CT diagnosed all distant metastases correctly.

PSF-PET/CT produced images with higher lesion-to-background contrast than conventional PET/CT, which allowed improved detection of lymph node metastasis without compromising specificity, and showed comparable diagnostic value to MRI in local staging. PSF-PET/CT is likely to have a great value for initial staging in rectal cancer.

• 18F-FDG pet/ct
• Pelvic MRI
• Point spread function (PSF)
• Rectal cancer
• Staging

• full-thickness excision
• gastrointestinal stromal tumors
• neuroendocrine tumors
• rare rectal tumor
• transanal endoscopic microsurgery

• Ovarian carcinoid
• carcinoid
• carcinoid heart
• carcinoid syndrome
• carcinoid tumor

• Aged
• Carcinoid Tumor/diagnosis
• Carcinoid Tumor/pathology
• Diagnosis, Differential
• Diarrhea/diagnosis
• Diarrhea/etiology
• Edema/diagnosis
• Edema/etiology
• Female
• Humans
• Leg
• Ovarian Neoplasms/diagnosis
• Ovarian Neoplasms/pathology

Squamous cell carcinoma (SCC) of the rectum is a rare clinical entity with an incidence rate of 0.1–0.25% per 1,000 cases. Though its etiology and pathogenesis remains unclear, it has been associated with chronic inflammation and infections. Herein, we report a case of an 82-year-old female who presented with a 2-month history of worsening abdominal pain, hematochezia, and bilateral inguinal lymphadenopathy with right-sided purulent discharge. Two years prior, she had had an unremarkable screening colonoscopy which met all quality indicators. Abdominal CT scan showed an irregular rectal mass with bulky pelvic and retroperitoneal adenopathy. Colonoscopy revealed one large circumferential nonobstructing lesion in the rectum. Endoscopic ultrasound confirmed its origin from the rectal wall with an enlarged perirectal lymph node. Cold biopsy followed by histopathology revealed SCC of the rectum.

• Endoscopic ultrasound
• Interval cancer
• Rectal carcinoma
• Screening colonoscopy

Water molecular diffusion in vivo tissue is much more complicated. We aimed to compare non-Gaussian diffusion models of diffusion-weighted imaging (DWI) including intra-voxel incoherent motion (IVIM), stretched-exponential model (SEM) and Gaussian diffusion model at 3.0 T MRI in patients with rectal cancer, and to determine the optimal model for investigating the water diffusion properties and characterization of rectal carcinoma. Fifty-nine consecutive patients with pathologically confirmed rectal adenocarcinoma underwent DWI with 16 b-values at a 3.0 T MRI system. DWI signals were fitted to the mono-exponential and non-Gaussian diffusion models (IVIM-mono, IVIM-bi and SEM) on primary tumor and adjacent normal rectal tissue. Parameters of standard apparent diffusion coefficient (ADC), slow- and fast-ADC, fraction of fast ADC (f), α value and distributed diffusion coefficient (DDC) were generated and compared between the tumor and normal tissues. The SEM exhibited the best fitting results of actual DWI signal in rectal cancer and the normal rectal wall (R² = 0.998, 0.999 respectively). The DDC achieved relatively high area under the curve (AUC = 0.980) in differentiating tumor from normal rectal wall. Non-Gaussian diffusion models could assess tissue properties more accurately than the ADC derived Gaussian diffusion model. SEM may be used as a potential optimal model for characterization of rectal cancer.

• Aged
• Carcinoma, Neuroendocrine/diagnosis
• Carcinoma, Neuroendocrine/surgery
• Cell Differentiation
• Colon, Sigmoid/pathology
• Colon, Sigmoid/surgery
• Colonic Neoplasms/diagnosis
• Colonic Neoplasms/surgery
• Colonoscopy
• Diagnosis, Differential
• Female
• Humans
• Prognosis

• Carcinoid
• Colon
• Hindgut
• Neuroendocrine
• Rectum

AIM: To provide an update on the aetiology, pathogenesis, diagnosis, staging and management of rectal squamous cell carcinoma (SCC).

METHODS: A systematic review was conducted according to the preferred reporting items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of Ovid MEDLINE was performed with the reference list of selected articles reviewed to ensure all relevant publications were captured. The search strategy was limited to the English language, spanning from 1946 to 2015. A qualitative analysis was undertaken examining patient demographics, clinical presentation, diagnosis, staging, treatment and outcome. The quantitaive analysis was limited to data extracted on treatment and outcomes including radiological, clinical and pathological complete response where available. The narrative and quantitative review were synthesised in concert.

RESULTS: The search identified 487 articles in total with 79 included in the qualitative review. The quantitative analysis involved 63 articles, consisting of 43 case reports and 20 case series with a total of 142 individual cases. The underlying pathogenesis of rectal SCC while unclear, continues to be defined, with increasing evidence of a metaplasia-dysplasia-carcinoma sequence and a possible role for human papilloma virus in this progression. The presentation is similar to rectal adenocarcinoma, with a diagnosis confirmed by endoscopic biopsy. Many presumed rectal SCC’s are in fact an extension of an anal SCC, and cytokeratin markers are a useful adjunct in this distinction. Staging is most accurately reflected by the tumour-node-metastasis classification for rectal adenocarcinoma. It involves examining locoregional disease by way of magnetic resonance imaging and/or endorectal ultrasound, with systemic spread excluded by way of computed tomography. Positron emission tomography is integral in the workup to exclude an external site of primary SCC with metastasis to the rectum. While the optimal treatment remains as yet undefined, recent studies have demonstrated a global shift away from surgery towards definitive chemoradiotherapy as primary treatment. Pooled overall survival was calculated to be 86% in patients managed with chemoradiation compared with 48% for those treated traditionally with surgery. Furthermore, local recurrence and metastatic rates were 25% vs 10% and 30% vs 13% for the chemoradiation vs conventional treatment cohorts.

CONCLUSION: The changing paradigm in the treatment of rectal SCC holds great promise for improved outcomes in this rare disease.

• Squamous cell carcinoma
• Rectal cancer
• Chemoradiotherapy
• Surgery
• Complete response