Nonsurgical Management Following Local Resection for Early Rectal Cancer in Patients with High-risk Factors: A Single-institute Experience

Objective

Additional surgery is considered for patients at high risk for lymph node metastasis (LNM) after local resection for early rectal cancer. Several factors are considered as indications for additional surgery, although there are currently no definitive criteria. This study aimed to clarify the need for additional surgery based on the number of risk factors for LNM and to evaluate the significance of submucosal invasion on recurrence.

Methods

Patients with early rectal cancer harboring risk factors for LNM who underwent local resection between March 2005 and December 2016 were retrospectively analyzed. Associations among the number of risk factors, prognosis, and additional treatment after local resection were investigated.

Results

A total of 29 eligible patients were classified into the surgery (n = 10), chemoradiotherapy (n = 7), and no-additional-treatment (NAT, n = 12) groups. Among the 29 patients, 15 patients (52%) with only one risk factor did not relapse. The NAT group harbored fewer risk factors for LNM, and 8 of the 12 patients (67%) had only deep submucosal invasion. Local recurrence occurred in one patient in the chemoradiotherapy group. The estimated 5-year overall survival rates were 88.9%, 75.0%, and 81.5% in the surgery, chemoradiotherapy, and NAT groups, respectively. There were no disease-specific deaths in the overall cohort.

Conclusions

In the present study, no recurrence occurred in patients who did not receive additional surgery with deep submucosal invasion as the only risk factor. A multicenter investigation is necessary to confirm the safety of nonsurgical options.

Upper Gastrointestinal Langerhans Cell Histiocytosis: A Report of 2 Adult Cases and a Literature Review

Langerhans cell histiocytosis (LCH) with primary involvement of the upper gastrointestinal (GI) tract is rare. We report 2 adult cases of localized LCH in the upper-GI tract, including the second reported adult case of esophageal LCH and review 11 previously reported cases. Case 1 involved the esophagus of a 61-year-old man; histiocytosis was detected when endoscopy was performed for an examination of epigastric pain. Case 2 involved the stomach of a 56-year-old woman wherein the lesion was detected during a follow-up endoscopy after Helicobacter pylori infection. Both biopsy specimens exhibited diffuse proliferation of mononuclear cells with nuclear convolution and a background of eosinophilic infiltrate. The cells were immunohistochemically positive for CD1a and langerin, and BRAF V600E mutation was detected in Case 2. Follow-up endoscopy for both cases revealed that the lesions disappeared without any treatment. It is important to avoid misdiagnosing LCH of the upper-GI tract as a malignant neoplasm.

Abstract 5877: Genetic analysis of metachronous pancreatic cancers

[Introduction] Early detection of pancreatic cancer is a key to curable surgery. However, many patients are diagnosed in an advanced stage and even in those cases who had a surgical resection of early stage tumors, metachronous pancreatic cancer in residual pancreas prevents cure. Thus, it is important to control metachronous tumors to improve clinical outcomes, whose pathogenesis is poorly understood. In this study, we aimed to reveal the origin of metachronous pancreatic cancers using an unbiased detection of somatic mutations in primary and metachronous cancers as well as adjacent precursor lesions. [Methods] Serially obtained formalin-fixed paraffin-embedded surgical specimens from 8 patient who had undergone curative surgery for an early stage pancreatic cancer were subjected to laser microdissection for the enrichment of tumor and PanIN lesions, from which DNA was extracted and analyzed for somatic mutations of each lesion by whole-exome sequencing (WES) with matched normal DNA. Based on shared and private mutations across different samples, we interrogated history of clonal evolution of these lesions. [Results] Pathology for primary cancer were margin-negative in all patients. The median interval between the initial and second surgery was 29.8 months (23 - 64.4 months). We analyzed a median of two cancer and one PanIN samples (0-5), from which we identified a median number of 45(range: 26-69) and 20 (14-42) somatic mutations using WES, respectively. None of the patients have known pathogenic germline variants. All samples had one or more driver mutations. In each patient, all driver mutations and more than half of passenger mutations were shared between primary and metachronous cancer samples, suggesting that those metachronous tumors are evolutionally closely related to the primary cancer. Negative pathology of the margins at the initial surgery suggested that those metachronous lesions originated from distant dissemination or metastasis, rather than contiguous, intraductal invasion. By contrast, none of the mutations other than hotspot KRAS mutations were shared between precursor lesions and cancer samples. Despite multiple independent clones in the precancerous lesion, all metachronous tumors originated from the primary lesions in this study. [Conclusions] Our study suggests that even early pancreatic cancer might be disseminated within the pancreas and contribute to metachronous cancers, suggesting the importance of close monitoring of the recurrence in the residual pancreas.

Citation Format: Hirano Tomonori, Nobuyuki Kakiuchi, Yasuhide Takeuchi, Yoshikage Inoue, Tomomi Nishimura, Yoichi Fujii, Akira Yokoyama, Hideki Makishima, Toshihiko Masui, Shinji Uemoto, Sachiko Minamiguchi, Hironori Haga, Kenichi Chiba, Hiroko Tanaka, Yuichi Shiraishi, Satoru Miyano, Norimitsu Uza, Yuzo Kodama, Hiroshi Seno, Seishi Ogawa. Genetic analysis of metachronous pancreatic cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5877.

Classification of glomerular pathological findings using deep learning and nephrologist-AI collective intelligence approach

BACKGROUND

Automated classification of glomerular pathological findings is potentially beneficial in establishing an efficient and objective diagnosis in renal pathology. While previous studies have verified the artificial intelligence (AI) models for the classification of global sclerosis and glomerular cell proliferation, there are several other glomerular pathological findings required for diagnosis, and the comprehensive models for the classification of these major findings have not yet been reported. Whether the cooperation between these AI models and clinicians improves diagnostic performance also remains unknown. Here, we developed AI models to classify glomerular images for major findings required for pathological diagnosis and investigated whether those models could improve the diagnostic performance of nephrologists.

METHODS

We used a dataset of 283 kidney biopsy cases comprising 15,888 glomerular images that were annotated by a total of 25 nephrologists. AI models to classify seven pathological findings: global sclerosis, segmental sclerosis, endocapillary proliferation, mesangial matrix accumulation, mesangial cell proliferation, crescent, and basement membrane structural changes, were constructed using deep learning by fine-tuning of InceptionV3 convolutional neural network. Subsequently, we compared the agreement to truth labels between majority decision among nephrologists with or without the AI model as a voter.

RESULTS

Our model for global sclerosis showed high performance (area under the curve: periodic acid-Schiff, 0.986; periodic acid methenamine silver, 0.983); the models for the other findings also showed performance close to those of nephrologists. By adding the AI model output to majority decision among nephrologists, out of the 14 constructed models, the results of the majority decision showed improvement in sensitivity for 10 models (four of them were statistically significant) and specificity for eight models (five significant).

CONCLUSION

Our study showed a proof-of-concept for the classification of multiple glomerular findings in a comprehensive method of deep learning and suggested its potential effectiveness in improving diagnostic accuracy of clinicians.

Rb and p53 Execute Distinct Roles in the Development of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PanNET) were classified into grades (G) 1 to 3 by the World Health Organization in 2017, but the precise mechanisms of PanNET initiation and progression have remained unclear. In this study, we used a genetically engineered mouse model to investigate the mechanisms of PanNET formation. Although pancreas-specific deletion of the Rb gene (Pdx1-Cre;Rb^f/f ) in mice did not affect pancreatic exocrine cells, the α-cell/β-cell ratio of islet cells was decreased at 8 months of age. During long-term observation (18-20 months), mice formed well-differentiated PanNET with a Ki67-labeling index of 2.7%. In contrast, pancreas-specific induction of a p53 mutation (Pdx1-Cre;Trp53^R172H ) had no effect on pancreatic exocrine and endocrine tissues, but simultaneous induction of a p53 mutation with Rb gene deletion (Pdx1-Cre;Trp53^R172H;Rb ^f/f ) resulted in the formation of aggressive PanNET with a Ki67-labeling index of 24.7% over the short-term (4 months). In Pdx1-Cre;Trp53^R172H;Rb^f/f mice, mRNA expression of Pten and Tsc2, negative regulators of the mTOR pathway, significantly decreased in the islet cells, and activation of the mTOR pathway was confirmed in subsequently formed PanNET. Thus, by manipulating Rb and p53 genes, we established a multistep progression model from dysplastic islet to indolent PanNET and aggressive metastatic PanNET in mice. These observations suggest that Rb and p53 have distinct roles in the development of PanNET. SIGNIFICANCE: Pancreas-specific manipulation of Rb and p53 genes induced malignant transformation of islet cells, reproducing stepwise progression from microadenomas to indolent (grade 1) and subsequent aggressive PanNETs (grade 2-3).

A familial case of alveolar capillary dysplasia with misalignment of the pulmonary veins: the clinicopathological features and unusual glomeruloid endothelial proliferation

Background

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare disorder of pulmonary vascular abnormality with persistent pulmonary hypertension of the newborn. The symptom usually presents within hours after birth, leading to an early demise. Heterozygous de novo point mutations and genomic deletions of the FOXF1 (forkhead box F1) gene or its upstream enhancer have been identified in most patients with ACD/MPV. Most cases of ACD/MPV are sporadic; however, familial cases are also reported in 10% of patients.

Case presentation

We herein report a case of familial ACD/MPV that showed unusual glomeruloid proliferation of endothelial cells. In this family, three of the four siblings died within two to 3 days after birth because of persistent pulmonary hypertension and respiratory failure. Only the second child remains alive and healthy. An autopsy was performed for the third and fourth children, resulting in a diagnosis of ACD/MPV based on the characteristic features, including misalignment of smaller pulmonary veins and lymphangiectasis. In both of these children, glomeruloid endothelial proliferation of vessels was noted in the interlobular septa. The vessels were immunohistochemically positive for D2–40, CD31, Factor VIII, and ERG, suggestive of differentiation for both lymphatic and blood vessels.

Conclusions

Unusual glomeruloid endothelial proliferation was observed in a familial ACD/MPV case. This histologic feature has not been described previously in ACD/MPV or any other pulmonary disease. Although the histogenesis of this histologic feature is unclear, this finding may suggest that ACD/MPV is a compound vascular and lymphovascular system disorder that exhibits various histologic features.

Uterine cervical squamous cell carcinoma without p16 (CDKN2A) expression: Heterogeneous causes of an unusual immunophenotype

Immunohistochemically p16 (CDKN2A)-negative uterine cervical squamous cell carcinoma (SCC) is uncommon, and there are few reports about its pathological features. This study explored the causes of p16 negativity in such cases. We analyzed diagnostic tissue samples of five cases of p16-negative cervical SCC among 107 patients who underwent hysterectomy at Kyoto University Hospital between January 2010 and December 2015. The samples were subjected to immunohistochemical staining, in situ hybridization and a genetic analysis. Two of five cases were positive for human papilloma virus (HPV) by genotyping. One was positive for HPV56 with promoter hypermethylation of CDKN2A and co-existing Epstein-Barr virus infection. Another was positive for HPV6 categorized as low-risk HPV with condylomatous morphology. Among the remaining three cases, one had amplification of the L1 gene of HPV with promoter hypermethylation of CDKN2A and TP53 mutation, and one of the other two HPV-negative cases had a homozygous CDKN2A deletion, while the other was positive for p53 and CK7. p16-negativity of cervical SCC is often associated with an unusual virus infection status and CDKN2A gene abnormality.

Microcystic, Elongated and Fragmented Pattern Invasion Can Adversely Influence Preoperative Staging for Low-grade Endometrial Carcinoma

Purpose:

To investigate the influence of microcystic, elongated and fragmented (MELF) pattern invasion on preoperative evaluation of lymph node (LN) metastasis and myometrial invasion in patients with low-grade endometrial carcinoma.

Methods:

The study included 192 consecutive patients with low-grade endometrial carcinoma who underwent preoperative computed tomography (CT) and magnetic resonance imaging (MRI), followed by surgery. One hundred sixty one of 192 patients underwent LN dissection and were analyzed for LN metastasis. All patients were analyzed for myometrial invasion. Presence of enlarged LN was evaluated by using size criteria on CT. Depth of myometrial invasion was evaluated on MRI using T₂-weighted imaging, diffusion-weighted imaging and contrast-enhanced T₁-weighted imaging comprehensively. Sensitivity and specificity for LN metastasis and deep myometrial invasion were evaluated for MELF group and non-MELF group. The difference of sensitivity between two groups was compared using Chi-square and Fisher’s exact test.

Results:

MELF pattern invasion was identified in 43/192 patients (22%). LN metastases were observed in 18/39 patients in MELF group and 6/122 patients in non-MELF group for pelvic LN and 11/29 patients in MELF group and 4/57 patients in non-MELF group for para-aortic LN. Sensitivity for the detection of pelvic LN metastasis in MELF group was significantly lower than in non-MELF group (16.7% vs 66.7%). As for the assessment of the deep myometiral invasion, pathological deep myometrial invasion were found in 31/43 patients in MELF group and 32/149 patients in non-MELF group. Sensitivity in MELF group showed lower values than in non-MELF group (54.8% vs 78.1% for reader 1, 54.8% vs 62.5% for reader 2), although there was no statistically significant difference (P = 0.09 for reader 1 and P = 0.72 for reader 2).

Conclusion:

In case of low-grade endometrial carcinoma with MELF pattern invasion, preoperative staging by CT and MRI have a risk for underestimation.

Comprehensive genomic profiling for chemotherapy-naïve advanced gastrointestinal malignancies

832

Background: From June, 2019, two comprehensive genomic profiling (CGP) assays, "FoundationOne CDx" and “OncoGuide NCC Oncopanel”, were reimbursed by the national insurance system in Japan for patients who were refractory to standard chemotherapy. However, their clinical utility for chemotherapy-naïve cancer patients is unknown. Methods: We conducted a single institutional prospective observational study to evaluate the clinical utility of FoundationOne CDx assay (Cambridge, MA, USA) for the patients with chemotherapy-naïve advanced gastrointestinal malignancies. Patients with adequate H.E. sample were registered in this study. Primary outcome was the detection rate of at least one actionable/druggable cancer genomic alterations. The evidence levels were classified according to clinical practice guidance for next-generation sequencing in cancer diagnosis and treatment (Edition 1.0) (Sunami K. Cancer Sci. 2018). Results: From October 2018 to June 2019, a total of 238 patients were screened and the following 158 patients were registered: colorectal cancer (n = 60), gastric cancer (n = 19), esophageal cancer (n = 23), pancreatic cancer (n = 30), biliary tract cancer (n = 11), rare gastrointestinal malignancies (n = 15). The CGP data were obtained for 113 patients . Median turn-around time was 14 days (range 10-247 days). Actionable/druggable cancer genomic alterations were observed in 113 patients (100%)/ 65 patients (57.5%), respectively. Clinically relevant biomarkers and genomic alterations were identified in 22 patients (19.5%); BRCA2 (n = 4), ERBB2 (n = 4) , BRAF (n = 3) , EGFR (n = 3), FGFR2 (n = 2), MET (n = 2), NTRK (n = 2) , MSI-H (n = 2 ), TMB-high (n = 2), ALK (n = 1) , KIT (n = 1) and ROS1 (n = 1). Of note, novel biomarkers such as ROS1- GOPC fusion and PALB2 rearrangement were obtained in the patients with esophageal squamous cell carcinoma. Conclusions: This is the first study to evaluate the clinical utility of CGP in patient with chemotherapy-naïve advanced gastrointestinal malignancies. Our result indicated that CGP might provide a chance of potentially effective drugs as a novel approach in precision cancer medicine. Clinical trial information: UMIN000034830.

Optimizing b-values for accurate depiction of pancreatic cancer with tumor-associated pancreatitis on computed diffusion-weighted imaging

PURPOSE

To determine the optimal b-value for accurate depiction of pancreatic cancer (PC) in patients with active tumor-associated pancreatitis (TAP), using computed diffusion-weighted imaging (cDWI) with a range of b-values up to 3000 s/mm².

METHODS

The study protocol was approved by the institutional review board. We retrospectively analyzed 34 consecutive PC cases with active TAP who underwent pancreatectomy without preoperative therapy. Four cDWI datasets with b-values of 1500-3000 s/mm² (cDWI₁₅₀₀-cDWI₃₀₀₀) were generated from the original DWI datasets with b-values of 0 and 1000 s/mm² obtained using a 3-T scanner. Two board-certified radiologists evaluated images qualitatively (tumor conspicuity and total image quality), and another two board-certified radiologists placed regions of interest for quantitative evaluations (apparent diffusion coefficient [ADC] values of both lesions, contrast ratio [CR] of PC to active TAP, and volume ratio [VR] of PC to surgical specimen).

RESULTS

As the b-value increased, tumor conspicuity improved significantly in cDWI₂₀₀₀ and cDWI₂₅₀₀ (P = 0.0121 and 0.0015, respectively), although total image quality decreased in all cDWIs compared with DWI₁₀₀₀ (P < 0.0001). Significantly lower ADC values were seen in PC (P < 0.0001). All cDWI groups showed positive correlation between the tumor conspicuity and ADC difference between PC and TAP. CR increased with the b-value, while VR decreased. Significant equivalence of VR to the surgical specimen was seen on cDWI₂₀₀₀ (P = 0.0031).

CONCLUSION

Accurate depiction of PC was optimal with cDWI₂₀₀₀ in the presence of active TAP.

Detection of Anaplastic Lymphoma Kinase-Rearranged Mesothelioma Cells in Ascites by Companion Diagnostics

BACKGROUND

A case of peritoneal mesothelioma with an anaplastic lymphoma kinase (ALK) translocation was identified, and we conducted further studies to obtain diagnostic and therapeutic insights. We believe that this is the first report describing the cytology of this new tumor type.

CASE

A teenage woman was referred for severe pleural effusion. Enhanced computed tomography indicated an abdominal mass with ascites. Laparoscopy revealed tumor dissemination from the pelvis to the upper abdomen. Because a high-grade serous carcinoma was suspected, ascitic cytology and biopsy were performed. Cytologically, the tumor displayed characteristics of both adenocarcinoma and reactive or neoplastic mesothelial cells. After extensive pathological evaluation, the tumor was diagnosed as malignant peritoneal mesothelioma. To verify the diagnosis and aid in developing a therapeutic strategy, several companion diagnostics were tried. Surprisingly, the tumor was ALK-positive, and ALK recombination was confirmed by an ALK break-apart test. Retrospectively, cells and tissue specimens were stained with ALK intercalated antibody-enhanced polymer. Tumor cells were clearly distinguished from the nonneoplastic background. Recombination in ALK was reconfirmed by the National Cancer Center Japan, and the patient was enrolled in a clinical trial for alectinib.

CONCLUSION

Companion diagnostics-based cytology may provide a useful means of monitoring and evaluating a molecular-targeted therapy.

Bone metastasis as a recurrence of early papillary adenocarcinoma of the stomach

Papillary adenocarcinomas of the stomach are rare and associated with a high rate of lymphovascular invasion and distant metastasis. However, the association between papillary adenocarcinoma and bone metastasis in gastric cancer remains largely unexplored. We report a rare case of bone metastasis as a recurrence of early papillary adenocarcinoma of the stomach after curative surgery. A 75-year-old man with a pedunculated polyp at the pylorus of the stomach was diagnosed with papillary adenocarcinoma after biopsy of the lesion, and the polyp was surgically resected. Pathohistological examination revealed intramucosal cancer without lymphovascular invasion or lymph node metastasis. Eight months after surgery, imaging studies showed osteolysis in the right sacrum, and the lesion was diagnosed as a bone metastasis after biopsy. The patient received palliative chemotherapy and radiotherapy for the bone metastasis, which resulted in relief of his leg pain. Subsequently, he was provided supportive care when his condition deteriorated, and he died 8 months after the diagnosis of bone metastasis. Our case shows that bone metastasis should not be overlooked, even though it is rare in gastric cancer patients. Papillary adenocarcinoma of the stomach should be carefully followed up through imaging examinations, even after curative resection.

Analytical performance of a new automated chemiluminescent magnetic immunoassays for soluble PD-1, PD-L1, and CTLA-4 in human plasma

Current clinically approved biomarkers for the PD-1 blockade cancer immunotherapy are based entirely on the properties of tumour cells. With increasing awareness of clinical responses, more precise biomarkers for the efficacy are required based on immune properties. In particular, expression levels of immune checkpoint-associated molecules such as PD-1, PD-L1, and CTLA-4 would be critical to evaluate the immune state of individuals. Although quantification of their soluble form leased from the membrane will provide quick evaluation of patients’ immune status, available methods such as enzyme-linked immunosorbent assays to measure these soluble factors have limitations in sensitivity and reproducibility for clinical use. To overcome these problems, we developed a rapid and sensitive immunoassay system based on chemiluminescent magnetic technology. The system is fully automated, providing high reproducibility. Application of this system to plasma of patients with several types of tumours demonstrated that soluble PD-1, PD-L1, and CTLA-4 levels were increased compared to those of healthy controls and varied among tumour types. The sensitivity and detection range were sufficient for evaluating plasma concentrations before and after the surgical ablation of cancers. Therefore, our newly developed system shows potential for accurate detection of soluble PD-1, PD-L1, and CTLA-4 levels in the clinical practice.

Comprehensive analysis of genetic aberrations linked to tumorigenesis in regenerative nodules of liver cirrhosis

BACKGROUND

Hepatocellular carcinoma (HCC) recurrently develops in cirrhotic liver containing a number of regenerative nodules (RNs). However, the biological tumorigenic potential of RNs is still unclear. To uncover the molecular bases of tumorigenesis in liver cirrhosis, we investigated the genetic aberrations in RNs of cirrhotic tissues using next-generation sequencing.

METHODS

We isolated 205 RNs and 7 HCC tissues from the whole explanted livers of 10 randomly selected patients who had undergone living-donor liver transplantation. Whole-exome sequencing and additional targeted deep sequencing on 30 selected HCC-related genes were conducted to reveal the mutational landscape of RNs and HCCs.

RESULTS

Whole-exome sequencing demonstrated that RNs frequently harbored relatively high-abundance genetic alterations, suggesting a clonal structure of each RN in cirrhotic liver. The mutation signature observed in RNs was similar to those determined in HCC, characterized by a predominance of C>T transitions, followed by T>C and C>A mutations. Targeted deep sequencing analyses of RNs identified nonsynonymous low-abundance mutations in various tumor-related genes, including TP53 and ARID1A. In contrast, TERT promoter mutations were not detected in any of the RNs examined. Consistently, TERT expression levels in RNs were comparable to those in normal livers, whereas every HCC tissue demonstrated an elevated level of TERT expression.

CONCLUSION

Analyses of RNs constructing cirrhotic liver indicated that a variety of genetic aberrations accumulate in the cirrhotic liver before the development of clinically and histologically overt HCC. These aberrations in RNs could provide the basis of tumorigenesis in patients with liver cirrhosis.

Abstract 5126: Genetic analysis of metachronous pancreatic cancers

[Introduction] Early detection of pancreatic cancer is a key to curable surgery, although many are diagnosed in advanced stage. However, even in those cases in which cancer was detected early enough for curative resection, metachronous pancreatic cancer may occur in residual pancreas, whose pathogenesis, including its relationship with primary cancer, has been poorly understood. In this study, we aimed to reveal the origin of metachronous pancreatic cancers using an unbiased detection of somatic mutations in primary and metachronous cancers as well as adjacent precursor lesions.

[Methods] Samples were obtained from longitudinal sampling from above lesions using laser microdissection from formalin-fixed paraffin-embedded surgical specimens. DNA was extracted and analyzed for somatic mutations of each lesion by whole-exome sequencing with matched normal DNA. On the basis of shared and private mutations across different samples, we interrogated history of clonal evolution of these lesions.

[Results] Four patients were enrolled who underwent curative surgery for early pancreatic cancer and subsequently for metachronous tumors in the residual pancreas. Pathology from surgery for primary cancer were margin-negative in all patients. The median interval between the initial and second surgery was 29.8 months (22.8 - 38.3 months). The number of precursor lesions analyzed was from 0 to 5 per patient. The median number of somatic mutations per sample was 78 (range: 41-92) in cancers and 20 (14-42) in precursor lesions. None of the patients have known pathogenic germline mutations. With a median of 78 and 20 mutations per sample, all samples had one or more driver mutations. In each case, all driver mutations that were detected in cancers were shared between primary and metachronous cancer. It indicated that metachronous cancer branched off from primary cancers at later stage of carcinogenesis. And negative margin at initial surgery suggested that metachronous cancer was formed by dissemination or metastasizing rather than Intraductal progression. By contrast, none of the mutations other than a hotspot KRAS mutations were shared between precursor lesions and cancers, suggesting multiple independent clonal growth of precancerous cells in the cancer bearing pancreas.

[Conclusions] Our study shows that metachronous pancreatic cancers are derived from the same origin of initial cancer. Therefore, even in the case of early pancreatic cancer careful checkup for recurrence in the residual pancreas is important.

Citation Format: Hirano Tomonori, Nobuyuki Kakiuchi, Yasuhide Takeuchi, Yoshikage Inoue, Tomomi Nishimura, Yoichi Fujii, Akira Yokoyama, Hideki Makishima, Toshihiko Masui, Shinji Uemoto, Sachiko Minamiguchi, Hironori Haga, Kenichi Chiba, Hiroko Tanaka, Yuichi Shiraishi, Satoru Miyano, Norimitsu Uza, Yuzo Kodama, Hiroshi Seno, Tsutomu Chiba, Seishi Ogawa. Genetic analysis of metachronous pancreatic cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5126.

Association Between Preanalytical Factors and Tumor Mutational Burden Estimated by Next-Generation Sequencing-Based Multiplex Gene Panel Assay

BACKGROUND

Tumor mutational burden (TMB) measured via next-generation sequencing (NGS)-based gene panel is a promising biomarker for response to immune checkpoint inhibitors (ICIs) in solid tumors. However, little is known about the preanalytical factors that can affect the TMB score.

MATERIALS AND METHODS

Data of 199 patients with solid tumors who underwent multiplex NGS gene panel (OncoPrime), which was commercially provided by a Clinical Laboratory Improvement Amendments-licensed laboratory and covered 0.78 megabase (Mb) of capture size relevant to the TMB calculation, were reviewed. Associations between the TMB score and preanalytical factors, including sample DNA quality, sample type, sampling site, and storage period, were analyzed. Clinical outcomes of patients with a high TMB score (≥10 mutations per megabase) who received anti-programmed cell death protein 1 antibodies (n = 22) were also analyzed.

RESULTS

Low DNA library concentration (<5 nM), formalin-fixed paraffin-embedded tissue (FFPE), and the prolonged sample storage period (range, 0.9-58.1 months) correlated with a higher TMB score. After excluding low DNA library samples from the analysis, FFPE samples, but not the sample storage period, exhibited a marked correlation with a high TMB score. Of 22 patients with a high TMB score, we observed the partial response in 2 patients (9.1%).

CONCLUSION

Our results indicate that the TMB score estimated via NGS-based gene panel could be affected by the DNA library concentration and sample type. These factors could potentially increase the false-positive and/or artifactual variant calls. As each gene panel has its own pipeline for variant calling, it is unknown whether these factors have a significant effect in other platforms.

IMPLICATIONS FOR PRACTICE

A high tumor mutational burden score, as estimated via next-generation sequencing-based gene panel testing, should be carefully interpreted as it could be affected by the DNA library concentration and sample type.

Solitary fibrous tumor arising from pelvic retroperitoneum: A report of two cases and a review of the literature

Solitary fibrous tumors (SFT) rarely arise in the pelvis. Here, we report two cases of SFT arising from the pelvic retroperitoneum. The first case involves a 64-year-old woman diagnosed with a 5-cm pelvic mass. Magnetic resonance imaging revealed a solid and cystic mass with marked enhancement, but limited water restriction. During surgery, intraligamental tumor arising near the round ligament was resected. Pathologically, the tumor comprised dilated vessels and spindle-shaped cells positive for STAT6 and CD34. The second case involves a 53-year-old woman diagnosed with a 4.5-cm pelvic mass through computed tomography. Magnetic resonance imaging demonstrated a solid mass with multiple cysts with strong enhancement and slight water restriction. During surgery, the tumor was found in the retroperitoneum. Pathologically, spindle-shaped tumor cells positive for STAT6 and CD34 had proliferated around the prominent hyalinized vessels. Although rare in the pelvis, SFT should be suspected when a mass with strong enhancement is found.

Aggressive adult granulosa cell tumor of the ovary without a FOXL2 mutation: A case report

We report a case of aggressive adult granulosa cell tumor (AGCT) of the ovary. On presentation, the tumor was localized in the right ovary; a total abdominal hysterectomy, bilateral salpingo-oophorectomy and partial omentectomy were performed. While some areas of the tumor represented typical AGCT, other areas showed enlarged and hyperchromatic nuclei with numerous mitoses (>10/high-power field) with marked necrosis. The results of immunohistochemical analysis were compatible with AGCT, except that, in the necrotic portion, p53 was strongly positive, and the Ki-67 index was high. Four months after laparotomy, recurrent tumors developed in the bones, liver, lungs and dura mater. The patient responded well to chemotherapy consisting of five cycles of paclitaxel and carboplatin, but later, the tumors rapidly proliferated, and the patient died of disease 11 months after laparotomy. FOXL2 examination demonstrated that both portions of the primary tumor did not have a point mutation (402C→G) specific to AGCT.

Recurrent Epstein-Barr Virus-positive (EBV+) Primary Central Nervous System Lymphoma (PCNSL) in a Patient with Clinical Features of Chronic Lymphocytic Inflammation with Pontine Perivascular Enhancement Responsive to Steroids (CLIPPERS)

Primary central nervous system lymphoma (PCNSL) and chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) can share clinical features and may be indistinguishable, even after brain biopsy. We encountered a case of Epstein-Barr virus-positive (EBV+) PCNSL recurrence in a patient with clinical features of CLIPPERS, and repeat brain biopsy was required to reach the correct diagnosis. Four years after the initial diagnosis and treatment of PCNSL, "peppering" punctate enhanced lesions with transient steroid responsiveness were detected during brain magnetic resonance imaging (MRI). A second brain biopsy supported a diagnosis of CLIPPERS, while a third biopsy confirmed the diagnosis of recurrent PCNSL.

Frequency and risk factors of thoracic metastases and optimisation of the use of cross-sectional chest imaging in follow-up patients with cervical cancer

AIM

To optimise cross-sectional chest imaging usage by identifying frequency and risk factors associated with thoracic metastases in cervical cancer patients after initial definitive treatment.

MATERIALS AND METHODS

This study, conducted during 2004-2015, examined 361 consecutive patients with histopathologically proven cervical carcinoma with at least 1 year of follow-up. Electronic medical records and all available imaging modes were used to record and assess patient and tumour characteristics and timing of thoracic metastases. Associations with these characteristics and thoracic metastases were assessed using univariate and multivariable Cox proportional hazards modelling.

RESULTS

Of the 361 patients, 31 developed thoracic metastases. Multivariate regression results showed that adeno/adenosquamous carcinomas (hazard ratio [HR], 2.46; 95% confidence interval [CI], 1.06 to 5.72), other histology (HR, 5.61; 95% CI, 1.81 to 17.42), high International Federation of Gynaecology and Obstetrics (FIGO) stage (HR, 2.84; 95% CI, 1.09 to 7.37), and presence of initial intra-abdominal lymph node metastases (HR, 2.46; 95% CI, 1.02 to 5.90) were associated significantly and independently with thoracic metastases. The second analysis among the subgroup of surgical treatment identified intermediate-high risk classification of recurrence (HR, 5.12; 95% CI, 1.14 to 22.94), high FIGO stage (HR, 2.73; 95% CI, 1.05 to 7.13), and other histology (HR, 11.51; 95% CI, 3.66 to 36.19) as independent predictors of thoracic metastases. Two of the 361 and 2/313 patients with thoracic metastases who did not correspond to the conditions above were in the respective evaluation groups.

CONCLUSION

Assessment of negative prognostic factors for thoracic metastases might contribute to reduced need for chest cross-sectional chest computed tomography examinations.