Usefulness of Ki-67 for predicting the metastatic potential of rectal carcinoids

Recurrence pattern and mapping of lymph node metastases from rectal neuroendocrine tumors

PURPOSE

There are as yet no data on the long-term clinical outcomes or the frequency of lymph node metastasis after surgical resection in patients with rectal neuroendocrine tumors (NETs). Our study investigated the long-term clinical outcomes and the frequency of lymph node metastasis in patients with rectal NETs treated by surgical resection.

METHODS

Fifty-one patients with rectal NETs who underwent rectal resection with total mesorectal excision between January 2000 and July 2020 at our hospital were enrolled. Twenty-eight patients had undergone preoperative endoscopic mucosal resection or endoscopic submucosal dissection before surgical resection. The indication for surgery was determined based on the Japan Neuroendocrine Tumor Society guidelines. Patients diagnosed with neuroendocrine carcinoma were excluded. Main outcome measures are frequency of pathological diagnosis of lymph node metastasis, site of lymph node metastasis, and the long-term prognosis after surgical resection.

RESULTS

Lymph node metastasis was observed in 20 patients (39.2%) with lateral lymph node metastasis occurring in 4 patients (7.8%). There was no significant association between lymph node metastasis and 5-year relapse-free survival (90% for metastasis-negative patients vs 58.1% for metastasis-positive patients, p = 0.094).

CONCLUSIONS

The rate of lymph node metastasis in patients with rectal NETs treated by surgical resection with total mesorectal excision was found to be high. However, a good prognosis was achieved by surgical resection even in patients with lymph node metastasis.

A case of a tiny neuroendocrine carcinoma in a large flat-elevated rectal tumor causing multiple liver metastases

Neuroendocrine tumors are rare malignancies comprising neuroendocrine cells widely distributed in the human body. They occur in various organs of the body, most commonly in the gastrointestinal tract and pancreas in the Japanese population. Mixed neuroendocrine-non-neuroendocrine neoplasm is included in the 2019 WHO classification and defined as having more than 30% of both neuroendocrine and non-neuroendocrine tumor components. However, the number of reports on mixed neuroendocrine and non-neuroendocrine tumors is particularly small. Herein, we encountered a rare case of a tiny neuroendocrine carcinoma in a large flat-elevated rectal tumor resulting in rapid multiple liver metastases. This case was referred to our institution for endoscopic submucosal dissection. Histopathological analysis showed that tubular adenocarcinoma and adenoma were the predominant lesions. Moreover, the neuroendocrine carcinoma component was less than 3% of the total tumor, measuring approximately 5 mm. However, the neuroendocrine carcinoma component was found to be the most advanced part of the infiltrate (T1b at least; SM3.8 mm). Repeat computed tomography 1 week after endoscopic submucosal dissection for evaluating intraoperative perforation revealed liver metastasis, and chemotherapy is currently underway.

Characteristics of colorectal neuroendocrine tumors in patients prospectively enrolled in a Japanese multicenter study: a first report from the C-NET STUDY

BACKGROUND

This is the first report from a multicenter prospective cohort study of colorectal neuroendocrine tumor (NET), the C-NET STUDY, conducted to assess the long-term outcomes of the enrolled patients. This report aimed to elucidate the clinicopathological features of the enrolled patients and lesions.

METHODS

Colorectal NET patients aged 20-74 years were consecutively enrolled and followed up at 50 institutions. The baseline characteristics and clinicopathological findings at enrollment and treatment were assessed.

RESULTS

A total of 495 patients with 500 colorectal NETs were included. The median patient age was 54 years, and 85.3% were asymptomatic. The most frequent lesion location was the lower rectum (88.0%); 99.4% of the lesions were clinically diagnosed to be devoid of metastatic findings, and 95.4% were treated with endoscopic resection. Lesions < 10 mm comprised 87.0% of the total, 96.6% had not invaded the muscularis propria, and 92.6% were classified as WHO NET grade 1. Positive lymphovascular involvement was found in 29.2% of the lesions. Its prevalence was high even in small NETs with immunohistochemical/special staining for pathological assessment (26.4% and 40.9% in lesions sized < 5 mm and 5-9 mm, respectively). Among 70 patients who underwent radical surgery primarily or secondarily, 18 showed positive lymph node metastasis.

CONCLUSIONS

The characteristics of real-world colorectal NET patients and lesions are elucidated. The high positivity of lymphovascular involvement in small NETs highlights the necessity of assessing the clinical significance of positive lymphovascular involvement based on long-term outcomes, which will be examined in later stages of the C-NET STUDY.

TRIAL REGISTRATION NUMBER

UMIN000025215.

Application of dual-layer spectral detector computed tomography to evaluate the expression of Ki-67 in colorectal cancer

BACKGROUND

Compared with traditional computed tomography (CT), dual-layer spectral detector CT (SDCT) shows significant improvement in imaging soft tissues of the digestive tract. This work aimed to explore the application of SDCT to evaluate the expression of the molecular marker Ki-67 in colorectal cancer.

METHODS

We retrospectively analyzed the imaging data of the SDCT (IQon Spectral CT; Philips Healthcare) of 45 patients with colorectal cancer in our centre. We used Spearman's test for the imaging parameters (reconstruction of 40, 70, and 100 keV virtual monoenergetic images [VMIs] and the slope of the Hounsfield unit attenuation plot [VMI Slope] based on venous phase CT images, the arterial phase iodine concentration [AP-IC] and venous phase iodine concentration [VP-IC], and the effective atomic number [Z effect]) and correlation analysis for the Ki-67 index. Multivariate logistic regression was used to eliminate confounding factors. We evaluated the expression level of Ki-67 and drew the receiver operating characteristic curve.

RESULTS

The 40-keV VMI, VMI Slope, and AP-IC were found to better reflect the Ki-67 index in patients with colorectal cancer with statistical significance. The 40-keV VMI (r = -0.612, p < 0.001) and VMI Slope (r = -0.523, p < 0.001) were negatively correlated with the Ki-67 index, and AP-IC (r = 0.378, p = 0.010) was positively correlated with the Ki-67 index. The other indexes (p > 0.05) were not statistically significant. The SDCT parameters demonstrated good performance, with area under curves of 0.785 for 40-keV VMI and 0.752 for AP-IC.

CONCLUSION

The SDCT parameters 40-keV VMI and AP-IC can be used for preliminary evaluation of the Ki-67 index in colorectal cancer.

Recommendation of long-term and systemic management according to the risk factors in rectal NETs patients

Rectal neuroendocrine tumors (NETs) are often found as small lesions, which can be treated by endoscopic resection. However, high risk cases with lymph node (LN) metastasis are indication of radical surgery. Furthermore, rectal NETs are often associated with late recurrences and/or multiple cancer development. Therefore, proper surgical indication and patients' management are required. We investigated the clinicopathological features of 79 rectal NET cases in order to elucidate risk factors for synchronous LN metastasis, recurrence, and multiple cancers. Recently, we reported that in pancreatic NET patients, a loss of heterozygosity (LOH) in PHLDA3 was associated with poorer prognosis, and that LOH of both PHLDA3 and MEN1 was frequently observed. Therefore, PHLDA3 and MEN1 LOH were also assessed in rectal NET patients for their association with clinicopathological features. Of the 79 patients, LN metastases were found in 12.7%, recurrences in 3.8%, and multiple cancers in 30.4% of the subjects. PHLDA3 and MEN1 LOH were found in 60.0% and 66.7% of the subjects, respectively. Lymphatic invasion and WHO classification 2010 were found to be independent risks for LN metastasis. There were three cases of recurrence, all of which occurred more than 3 years after resection and two of which exhibited LN metastasis. Older age and LOH in PHLDA3 were associated with the presence of multiple cancers. Long-term and systemic management of patients with rectal NETs is therefore recommended in accordance with these risk factors.

Ileocolonic neuroendocrine tumours identified in the English bowel cancer screening programme

AIM

Ileocolonic neuroendocrine tumours (NETs) are diagnosed as part of bowel cancer screening programmes (BCSPs). The aim of this study was to identify and characterize NETs diagnosed within the English BCSP, a double-screen programme that uses guaic faecal occult blood test (gFOBT) screening and colonoscopy, by interrogating the national colorectal screening database and validating the findings with individual BCSP centres.

METHOD

The Exeter database was interrogated by running queries to identify participants with coded NETs (from the start of the programme in July 2006 - 1 December 2014). A written proforma was sent to the responsible BCSP clinician for validation and characterization.

RESULTS

During this period, 13 061 716 participants were adequately screened using gFOBTs, and 259 765 participants had definitively abnormal results. There were 146 unique participants with NET-related codes from 216 707 BCSP colonoscopies. The diagnosis rates per 100 000 colonoscopies were 29 rectal, 18 colonic and 11 ileal NETs. The majority of rectal NETs had Grade 1 (80%) and Stage T1 (85.1%) disease. Over half of ileal NETs (53.6%) in this study had invasive disease, with 85.2% having nodal and 36.1% having metastastatic disease.

CONCLUSION

The current study highlights the rate of colorectal NETs diagnosed in the English BCSP. These data highlight a higher-than-anticipated incidence, and the potential additional benefit of BCSPs in identifying occult NETs.

A 10-year History of a Diminutive Rectal Neuroendocrine Tumor

A 39-year-old woman underwent a preoperative diagnostic colonoscopy for cervical cancer. A 3-mm neuroendocrine tumor (NET) was incidentally detected in the rectum. The NET was observed via 7 colonoscopies over 10 years while giving priority to treating the cervical cancer. Complete cervical cancer remission was confirmed at the 10-year follow-up examination; therefore, endoscopic treatment for the NET was subsequently performed. The NET showed almost no change in either size or morphology over the 10-year period. This case illustrates the possible very-slow progression of a small NET, suggesting its benign behavior.

Predictive Factors for Lymph Node Metastasis and Prognostic Factors for Survival in Rectal Neuroendocrine Tumors

INTRODUCTION

Neuroendocrine tumors have malignant potential, and lymph node metastasis can occur. This study aimed to identify predictive factors of lymph node metastasis and prognostic factors for survival in rectal neuroendocrine tumors.

METHODS

Sixty-four patients underwent endoscopic or surgical treatment for rectal NET. The data on these patients were collected in our database prospectively and reviewed retrospectively.

RESULTS

Transanal excision was performed in 28 (43.8%) patients, endoscopic mucosal resection or submucosal dissection was performed in 15 (23.4%) patients, and radical resection was performed in 21 (31.8%) patients. Lymph node and distant metastasis was present in 16 (25.0%) and fir (7.8%) patients. The significant risk factors for lymph node metastasis identified in the multivariable analyses were tumor size (≥ 2 cm, p = 0.003) and tumor grade (G2, p < 0.001; G3, p = 0.008). In patients with a tumor smaller than 2 cm, the risk factors for lymph node metastasis included the tumor grade, mitosis count, and Ki-67 index. The median follow-up period was 30.0 months, and recurrence developed in four (6.8%) patients. The significant prognostic factors for survival included tumor size, T stage, lymph node metastasis, and tumor grade.

CONCLUSION

Tumor grade combined with tumor size is an important predictive factor for lymph node metastasis and could serve as a prognostic factor for survival outcomes.

Can the Ki-67 Labeling Index in Biopsy Specimens Predict the World Health Organization Grade of Rectal Neuroendocrine Tumors?

BACKGROUND

Being grade 2 is a known risk factor for metastasis in rectal neuroendocrine tumors (R-NETs). We aimed to identify the efficacy of the Ki-67 labeling index (LI) in endoscopic biopsy specimens to predict the World Health Organization (WHO) grade of R-NETs.

METHODS

A total of 59 patients with 60 R-NETs (43 WHO grade 1 and 17 WHO grade 2), treated between October 2002 and December 2014, were retrospectively evaluated. The patients included in the study underwent biopsies followed by endoscopic submucosal resection with a ligation device, trans-anal full-thickness surgical resection, or radical surgery with lymph node dissection. The Ki-67 LI in the biopsy and resected specimens were compared between the 2 tumor grade groups, and the diagnostic sensitivity, specificity, and positive and negative predictive values for the detection of WHO grade 2 tumors were evaluated.

RESULTS

The sensitivity, specificity, and positive and negative predictive values of the Ki-67 LI in biopsy specimens for predicting grade 2 tumors were 53% (9 of 17), 95% (41 of 43), 100% (9 of 9), and 87% (41 of 47), respectively. Pearson's rank correlation coefficient between the Ki-67 LI in the biopsy and resected specimens was 0.92.

CONCLUSIONS

The Ki-67 LI of the biopsy specimen is useful for determining the appropriate treatment for R-NETs.

Review article: the investigation and management of rectal neuroendocrine tumours

BACKGROUND

Rectal neuroendocrine tumours (NETs) are increasingly identified at endoscopy possibly as a result of bowel cancer screening programmes.

AIM

To present a review of the literature to aid clinicians in the diagnosis and management of rectal neuroendocrine tumours.

METHODS

A literature search was conducted through MEDLINE using search terms: rectal, rectum, carcinoid, NET, therapy, endoscopy, mucosal resection, submucosal dissection. Relevant articles were identified through manual review with reference lists reviewed for additional articles.

RESULTS

The incidence of rectal neuroendocrine tumours is approximately 1 per 100 000 population per year with the majority (80-90%) being <1 cm and localised to the submucosa. Metastatic disease is infrequent (<20%) with risk factors including size, atypical appearance, grade and depth of invasion. The primary resection modality influences complete resection rates and the need for secondary therapy. A thorough pre-resection diagnostic work up is required for lesions that are at higher risk of invasion and metastasis. Device-assisted endoscopic mucosal resection and endoscopic submucosal dissection are used to resect localised rectal neuroendocrine tumours <2 cm. Transanal surgery is also used to resect localised 1-2 cm rectal neuroendocrine tumours. Oncological surgical resection is used for rectal neuroendocrine tumours that are >2 cm or with invasion and regional disease. The treatment of advanced disease is multimodal.

CONCLUSIONS

The long-term tumour biology of small rectal neuroendocrine tumours remains unclear. There is uncertain impact from bowel cancer screening programmes on rectal neuroendocrine tumour incidence, morbidity and mortality. Referral to neuroendocrine tumour centres for patients with locally advanced disease or metastatic disease is recommended.

Usefulness of Ki-67, Mitoses, and Tumor Size for Predicting Metastasis in Carcinoid Tumors of the Lung: A Study of 48 Cases at a Tertiary Care Centre in Canada

Background. Evaluation of Ki-67 index in lung carcinoid tumors (LCTs) has been of interest in order to identify high risk subsets. Our objectives are (1) to evaluate the usefulness of Ki-67 index, mitoses, and tumor size in predicting metastasis and (2) to compare the Manual Conventional Method (MCM) and the Computer Assisted Image Analysis Method (CIAM) for Ki-67 calculation. Methods. We studied 48 patients with LCTs from two academic centres in Canada. For Ki-67 calculation, digital images of 5000 cells were counted using an image processing software and 2000 cells by MCM. Mitoses/10 HPF was counted. Results. We had 37 typical carcinoids (TCs) and 11 atypical carcinoids (ACs). 7/48 patients developed metastasis. There was a positive relationship between metastasis and carcinoid type (P = 0.039) and metastasis and mitoses (≥2) (P = 0.017). Although not statistically significant, the mean Ki-67 index for ACs was higher than for TCs (0.95% versus 0.72%, CIAM, P = 0.299). Similarly, although not statistically significant, the mean Ki-67 index for metastatic group (MG) was higher than for nonmetastatic group (NMG) (1.01% versus 0.71% by CIAM, P = 0.281). However when Ki-67 index data was categorized at various levels, there is suggestion of a useful cutoff (≥0.50%) to predict metastasis (P = 0.106, CIAM). A significantly higher proportion of patients with mitosis ≥2 and Ki-67 index ≥0.50% had metastasis (P = 0.033) compared to other patients. Similarly patients with tumor size ≥3 cm and Ki-67 ≥0.50% had a greater percentage of metastases than others (P = 0.039). Although there was a strong correlation between two (MCM versus CIAM) counting methods (r = 0.929, P = 0.001), overall the calculated Ki-67 index was slightly higher by MCM (range 0 to 6.4, mean 1.5) compared to CIAM (range 0 to 2.9, mean 0.75). Conclusion. This study confirms that mitoses ≥2 is a powerful predictor of metastasis in LCTs. Although this is a small sample size, there is suggestion that analysis of Ki-67 index along with mitoses and tumor size may be a useful adjunct for predicting metastasis in LCTs.

Excellent prognosis following endoscopic resection of patients with rectal neuroendocrine tumors despite the frequent presence of lymphovascular invasion

BACKGROUND

Endoscopic resection (ER) has been increasingly used for the treatment of rectal neuroendocrine tumors (NETs); however, only limited data are available on its long-term outcomes. This study analyzed the long-term outcomes of rectal NETs treated by ER and characterized potential risk factors for metastasis in these cases, with emphasis on lymphovascular invasion.

METHODS

We retrospectively analyzed the clinicopathological features and outcomes of 86 patients with 90 rectal NETs who had been treated by ER. Lymphovascular invasion was reevaluated using elastic-staining and double-staining immunohistochemistry.

RESULTS

En bloc resection with tumor-free margins was achieved in 87 lesions (96.7%). The median tumor size was 5 mm (range 2-13), and all the lesions were confined to the submucosal layer. The Ki-67 index was less than 3% in all the lesions, which were therefore classified as NET G1. Elastic-staining and double-staining immunohistochemistry revealed the presence of lymphatic and venous invasion in 23 (25.6%) and 35 lesions (36.7%), respectively. Collectively, lymphatic and/or vascular invasion was identified in 42 lesions (46.7%). All cases were followed up without additional surgery, and no metastasis or recurrence was detected during the median follow-up period of 67.5 months.

CONCLUSIONS

This study showed an excellent long-term prognosis following ER of patients with rectal NETs, confirming that ER is a valid treatment option for small rectal NETs. The present study also revealed highly prevalent lymphovascular invasion even in minute rectal NETs; this observation raises a question regarding its significance as a risk factor for metastasis.

Natural course of an untreated metastatic perirectal lymph node after the endoscopic resection of a rectal neuroendocrine tumor

Lymph node metastasis is rare in small (i.e., <10 mm) rectal neuroendocrine tumors (NETs). In addition to tumor size, pathological features such as the mitotic or Ki-67 proliferation index are associated with lymph node metastasis in rectal NETs. We recently treated a patient who underwent endoscopic treatment of a small, grade 1 rectal NET that recurred in the form of perirectal lymph node metastasis 7 years later. A 7-mm-sized perirectal lymph node was noted at the time of the initial endoscopic treatment. The same lymph node was found to be slightly enlarged on follow-up and finally confirmed as a metastatic NET. Therefore, the perirectal lymph node metastasis might have been present at the time of the initial diagnosis. However, the growth rate of the lymph node was extremely low, and it took 7 years to increase in size from 7 to 10 mm. NETs with low Ki-67 proliferation index and without mitotic activity may grow extremely slowly even if they are metastatic.

Management of sub-5 mm rectal carcinoids with lymph node metastases

Minute (<5 mm) and small (5–10 mm) rectal carcinoids discovered during colonoscopy are generally considered to be non-aggressive, and the management and surveillance of patients with this entity are usually limited. We present the case of a 61-year-old Chinese female with multiple sub-5 mm carcinoid tumours in the rectum without any computed tomography (CT) evidence of lymph node or distant metastases. She underwent an ultra-low anterior resection for a sessile rectal polyp with the histological appearance of a moderately differentiated adenocarcinoma. Seven foci of minute carcinoids in the rectum and perirectal lymph node metastastic spread from the carcinoid tumours were also discovered on histopathology. There were no lymph node metastases originating from adenocarcinoma. This case report and review of the literature suggests that minute rectal carcinoids are at risk of metastasizing and that these patients should be investigated for lymph node and distant metastatic spread with CT and somatostatin receptor scintigraphy or its equivalent, as this would influence prognosis and surgical management of these patients. Findings relating to lymphovascular invasion, perineural invasion, high Ki-67, mitotic rate, depth of tumour invasion, central ulceration, multifocal tumours and size are useful in predicting metastases and may be used in scoring tools. Size alone is not a good predictor of metastastic spread.

Multiple carcinoid tumors of the rectum: report of two cases suggesting the origin of carcinoid tumors

Two cases of multiple carcinoid tumors of the rectum with numerous micronests of carcinoid tumors are reported. The patients were 51- and 58-year-old males. Many carcinoid tumors and numerous carcinoid micronests were found in the resected rectum; the total number of carcinoid tumors, groups of micronests, and solitary micronests was 69 in the first case and 62 in the second case. The micronests, consisting of a few to many endocrine cells, were observed in the lamina propria, muscularis mucosa, and/or submucosa. Micronests increased in number, gathered and formed carcinoid tumors, which were up to 8 mm in diameter. It was found that a nest of the carcinoid tumors in the lamina propria showed continuity with the endocrine cells of a crypt in the different carcinoid tumors in both cases. The carcinoid tumor and micronest infiltrated the nerves and ganglions in the muscularis mucosa and submucosa. Nests of the carcinoid tumors and micronests were surrounded by S-100-positive cells. Lymph node metastases of the carcinoid tumor were found in both cases. Rectal carcinoid tumors may originate from endocrine cells of the crypts, and multiple carcinoid tumors may occur heterogeneously.

Role of Ki-67 proliferation index in the assessment of patients with neuroendocrine neoplasias regarding the stage of disease

BACKGROUND

Neuroendocrine neoplasias (NEN) of the gastroenteropancreatic (GEP) system frequently present with metastatic deposits. The proliferation marker Ki-67 is used for diagnosis and to assess the prognosis of disease. The aim of our study was to evaluate the usefulness of Ki-67 % in the assessment of NEN patients with regard to their disease stage in clinical practice. Additionally, a comparative analysis of Ki-67 levels among different sites of disease was performed.

METHODS

This retrospective study included patients with GEP NEN referred to our center from 2010 to 2012. The NEN diagnosis was confirmed by standard histopathology. Ki-67 immunohistochemistry was done on paraffin-embedded sections using an automated Leica immunohistochemistry machine. NEN grading was carried out according to European Neuroendocrine Tumor Society recommendations (low grade [G1] to intermediate grade [G2], well to moderately differentiated neuroendocrine neoplasms; high-grade [G3], moderately to poorly differentiated neuroendocrine neoplasms). Results of tumor staging and grading were correlated. In a subgroup of cases, comparative analysis of Ki-67 levels in different sites of disease was carried out.

RESULTS

One hundred sixty-one GEP NEN patients were included in the study. Metastatic disease was seen in 46.1 % (53/115) of G1 tumors, 77.8 % (28/36) of G2 tumors, and 100 % of (10/10) G3 tumors (p = 0.0002). When stratified according to primary tumor site, metastatic disease was documented in 42.9 % (36/84) of patients with pancreatic NEN and in 91.9 % (34/37) of those with small intestinal primary. Stage IV metastatic disease was present in 27.8 % (32/115) and 72.2 % (26/36) of the G1 and G2 tumors, respectively, and in 90 % (9/10) of the G3 tumors. Assessment of the Ki-67 index for a subset of cases at metastatic sites as well as the primary tumor site showed discrepancies in 35.3 % cases. In 7/9 (77.8 %) patients with liver metastases, Ki-67 % was higher in the liver lesions than in the primary tumor.

CONCLUSIONS

Patients with GEP NEN exhibiting a high Ki-67 proliferation index present with metastatic disease in the vast majority of cases. Depending upon the primary tumor site, metastases are to be expected also in tumors with low Ki-67 %, although they are considered less aggressive. Different disease sites may express heterogeneous Ki-67 levels.

Prognostic significance of Ki-67 expression in rectal carcinoid tumors

BACKGROUND/AIMS

Rectal carcinoid tumors can be resected with endoscopy, and it is important to assess their prognostic factors. We evaluated the potential of Ki-67 expression as a prognostic factor in rectal carcinoid tumors.

METHODS

We retrospectively reviewed the medical records of 37 patients with rectal carcinoid tumors who got endoscopic resection from January 2001 to January 2011 at Inje University Seoul Paik Hospital. We analyzed their endoscopic and histologic findings, Ki-67 expression, clinical outcome, and prognosis.

RESULTS

The mean age (±SD) of the patients was 56.3±10.7 years, and the male : female ratio was 3.6 : 1. The mean tumor size was 0.5±0.4 cm, 33 patients showed grade 1 tumors (89.2%) and the average Ki-67 expression was 0.7±1.2%. Thirty five patients underwent endoscopic mucosal resection, and two required endoscopic submucosal dissection. Eight patients had positive margins after resection, but no cases of lymphovascular invasion were identified. The median follow-up duration was 21.4±25.4 months, and no recurrences were observed.

CONCLUSIONS

In low grade rectal carcinoid tumors which are lack of central depression on colonoscopy, the expression of a molecular marker of malignant potential, Ki-67, was low. Therefore, endoscopic resection seemed to be a safe and effective treatment for these tumors.

Factors associated with lymph node metastasis in radically resected rectal carcinoids: a systematic review and meta-analysis

BACKGROUND

Although various guidelines regarding neuroendocrine tumors were released, treatment for rectal neuroendocrine tumors with size between 1 and 2 cm has not been explicitly elucidated. The determinant factor of the choice between endoscopic resection and radical surgery is whether lymph node involvement exists.

AIM

This study aims to explore factors associated with lymph node involvement in rectal neuroendocrine tumors by conducting a meta-analysis.

METHODS

A broad literature research of Pubmed, Embase&Medline, and The Cochrane Library was performed, and systematic review and meta-analysis about factors associated with lymph node involvement were conducted.

RESULTS

Seven studies were included in this meta-analysis. Tumor size > 1 cm (odds ratio (OR) 6.72, 95% confidence interval (CI) [3.23, 14.02]), depth of invasion (OR 5.06, 95% CI [2.30, 11.10]), venous invasion (OR 5.92, 95% CI [2.21, 15.87]), and central depression (OR 3.00, 95% CI [1.07, 8.43]) were significantly associated with lymph node involvement.

CONCLUSION

The available clinical evidence suggests that tumor size > 1 cm, invasion of muscularis properia, venous invasion, and central depression could be risk factors of lymph node involvement, while other factors reported by few studies need further research.

Clinicopathological characteristics of rectal carcinoid patients undergoing surgical resection

The aim of this study was to clarify the clinical aspects, histopathological features and prognosis of patients with rectal carcinoids, focusing on properties associated with metastasis, in order to gain insights into appropriate management. A total of 20 patients (15 males, 5 females; mean age, 54.9 years; range, 23-71) who underwent surgery for rectal carcinoid tumors at the Department of Colorectal Surgery, Hyogo College of Medicine, between May 2000 and January 2011 were analyzed. Ki-67 immunostaining was performed in 13 cases with available tumor tissue specimens. Of the 20 patients, a radical operation including rectal resection with a lymphadenectomy was performed in 16. The mean tumor size was 11.9 mm (3-25 mm) and lymph node metastasis was confirmed in 9 cases, including 3 with lesions no greater than 7 mm in diameter. Overall, 16 (80%) of the tumors were localized in the submucosal layer and 4 (20%) involved the proper muscle layer. Ki-67 labeling index and lymphovascular invasion were shown to be associated with lymph node and/or distant metastasis by multiple logistic regression analysis, but were not statistically significant in ANOVA findings. Lymph node metastasis from rectal carcinoids, even those smaller than 10 mm in diameter, was not a rare event. More attention should be given to decision-making, including the possibility of endoscopic resection for the treatment of rectal carcinoid tumors regardless of size.

Ki-67 proliferative index predicts progression-free survival of patients with well-differentiated ileal neuroendocrine tumors

Ki-67 proliferative index (Ki-67 index) is suggested to be an important prognostic variable and is included as one of the grading parameters for neuroendocrine tumors. The present study was undertaken to determine the usefulness of the Ki-67 index and the corresponding tumor grade in predicting progression-free survival (PFS) of patients with ileal well-differentiated neuroendocrine tumors (wNETs). Tumors from 57 patients with ileal wNETs were studied. Immunohistochemical staining for Ki-67 was performed on the primary as well as selected metastatic tumors and quantitated by computer-assisted image analysis using the Ariol system. The tumors were graded based on mitotic activity and Ki-67 index. Clinical and pathological variables affecting the PFS were analyzed. There were 29 women and 28 men, with a mean age of 59 years. At the time of initial presentation, 8 patients (14%) had localized disease (stages I and II), 29 patients (51%) had regional (nodal/mesenteric) spread (stage III), and 20 patients (35%) had distant metastasis (stage IV). Twelve patients experienced disease progression during subsequent follow-up. Patients with initial stage IV disease were more likely to experience disease progression (P = .005). Additionally, higher histological grade (as determined by Ki-67 index >2%) was associated with a decreased PFS (P = .001). Ki-67 index greater than 2% at either the primary site or the metastatic site was found to be the only significant predictor of PFS after consideration of all other variables in an adjusted analysis. In conclusion, the Ki-67 index predicts PFS of patients with ileal wNETs.

Small carcinoid tumor of papilla of the Vater with lymph node metastases

INTRODUCTION

Carcinoid of papilla of the Vater is a rare entity. Detailed prognostic factors of this tumor have not yet been elucidated, and treatment choices include local resection and pancreatoduodenectomy with excision of lymph nodes.

CASE REPORT

A 59-year-old woman, who was diagnosed with liver dysfunction and underwent a cholecystectomy, was referred to our institution with a suspected ampullary tumor. Computed tomography showed 1 cm of enhancement at the duodenal ampulla, but no visible lymph adenopathy. In the duodenoscopic view, her papilla was slightly enlarged without orifice, so that forceps biopsy was performed from the common ampullary channel after needle-knife incision. Tissue obtained by biopsy revealed a possible carcinoid tumor, with 1.1% of Ki-67 labeling index. Pancreatoduodenectomy was performed, and the resected specimen showed a carcinoid tumor of the ampulla, 1.2 cm in diameter, with metastases to regional lymph nodes and a 4% Ki-67 labeling index. It is suggested that despite the small size and low proliferation index, an ampullary carcinoid may not be cured by local resection. Clinicians must pay careful attention to the choice of treatment and monitoring after the resection.

Clinicopathological characteristics and prognosis of rectal well-differentiated neuroendocrine tumors

BACKGROUND

To clarify the oncological outcome of rectal well-differentiated neuroendocrine tumors (W/D NETs), we examined the clinicopathological characteristics and prognosis of patients with this neoplasm.

MATERIALS AND METHODS

A total of 23 patients who underwent surgical treatment with lymph node dissection for rectal W/D NETs between 1973 and 2007 were reviewed.

RESULTS

Median tumor size measured preoperatively was 13 mm (range, 4-25 mm), and the median number of dissected lymph nodes was 16 (range, 1-46). The incidence of lymph node metastasis was 61% (14 of 23 cases). The smallest W/D NETs with lymph node metastasis was 10 mm in diameter. All the patients without lymph node metastasis survived without recurrence. Among 11 patients who had only regional lymph node metastasis, only one developed liver metastasis and died 13 months after initial surgery. Among three patients with lateral pelvic lymph node metastasis, two survived more than 5 years, although two had liver metastasis.

CONCLUSIONS

Because the incidence of lymph node metastasis is very high in patients with rectal W/D NETs greater than 10 mm in diameter, radical surgery is required. In this series, the outcome of rectal W/D NETs patients with lateral pelvic lymph node metastasis was better than expected.

Neuroendocrine tumors of the diffuse neuroendocrine system

PURPOSE OF REVIEW

Neuroendocrine tumors (previously referred to as carcinoids) are ill-understood, enigmatic malignancies that, although slow-growing compared with adenocarcinomas, can behave aggressively. In 2004, they comprised 1.25% of all malignancies; their incidence is increasing by approximately 6% per year. The present review provides an overview on neuroendocrine tumors and focuses on general features and current diagnostic and therapeutic options.

RECENT FINDINGS

Neuroendocrine tumors may present a considerable diagnostic and therapeutic challenge as their clinical presentation is nonspecific and usually late, when metastases are already evident. Topographic localization is by computed tomography, magnetic resonance imaging, somatostatin receptor scintigraphy, whole-body positron emission tomography or endoscopy/ultrasound. Bronchoscopy is useful to verify the diagnosis when lesions are located centrally in the bronchi. No curative treatment except for radical surgery (almost never feasible) exists. Palliative and symptomatic treatment is based on surgical debulking, tumor embolization, and biotherapy with somatostatin analogues. Chemotherapy and radiotherapy are usually ineffective, but novel drugs such as tyrosine kinase receptor inhibitors show promising results in phase II clinical studies.

SUMMARY

Tumors of the diffuse neuroendocrine system represent a significant and increasing clinical problem, and there is a need to develop both early diagnostic tests as well as to establish targeted therapeutic strategies.

Endoscopic submucosal resection with a ligation device is an effective and safe treatment for carcinoid tumors in the lower rectum

BACKGROUND AND AIMS

Various methods for complete endoscopic resection of rectal carcinoid tumors have been reported; however, the number of cases investigated in each study has been limited. The aim of the present study was to clarify the clinical usefulness of a novel technique named endoscopic submucosal resection with a ligation device (ESMR-L) in a large number of rectal carcinoid tumors.

PATIENTS AND METHODS

Between January 1999 and March 2005, a total of 61 patients with 63 rectal carcinoid tumors estimated at 10 mm or less in diameter, without atypical features and resected by ESMR-L were recruited for this analysis. The complete resection rate, complications associated with the procedure, local recurrence, and distant metastases were evaluated.

RESULTS

Sixty-one patients were 36 males and 25 females with a mean age of 59 +/- 11 years (24-76 years). Tumor size ranged from 2 to 12 mm in diameter, with an average size of 6.4 +/- 2.4 mm. Fifty-nine lesions (93.6%) were located in the lower rectum (Rb), three in the upper rectum (Ra) and one in the recto-sigmoid colon (Rs). In total, 60 out of 63 lesions (95.2%) were histologically determined to be completely resected. The complete resection rate for lesions located in the Rb was 98.3%, which was significantly higher than that for lesions in Ra and Rs (50%). Minor bleeding associated with the procedure occurred in five lesions (7.9%), but all cases were successfully managed with hemoclips. Histopathologically, all tumors were located in the submucosal layer, and all were classified as classical-type carcinoids without lymphovascular invasion. Neither local recurrence nor distant metastasis was detected during a median follow-up period of 24 months.

CONCLUSION

In a large number of cases, ESMR-L proved to be a useful and safe procedure to resect rectal carcinoid tumors 10 mm or less in diameter, especially for those located in the Rb.

Predicting prognosis in gastroentero-pancreatic neuroendocrine tumors: an overview and the value of Ki-67 immunostaining

Gastroenteropancreatic neuroendocrine tumors (GEP-NETS) are unusual and rare neoplasms for which prognostic assessment and the diagnosis of malignancy, on the basis of histology alone, represent considerable challenges for the pathologist. To date, many molecular markers have been identified with a view to providing accurate and timely prediction of response to treatment and long-term survival. Proliferation remains a key feature of tumor progression, which has been widely estimated by the immunohistochemical use of the Ki-67 nuclear antigen. Given the continued difficulties inherent in prediction of malignancy in pancreatic neuroendocrine tumors (PETs) in particular, it has become unclear whether Ki-67 is truly a reliable prognostication marker. This review seeks to better establish what the consensus is on the role of the Ki-67 proliferation index as a prognostic indicator of long-term outcome in pancreatic neuroendocrine tumors. We conclude that most studies favor the utility of the Ki-67 proliferation index despite different critical percentages and in concert with other pathological parameters in the routine work-up of PETs.