Objective: The study aimed to describe and compare minimally invasive surgery (MIS) and open surgery for rectal cancer in Peru. Material and methods: A retrospective single-center analysis was performed for all patients who underwent sphincter- sparing surgery for non-metastatic rectal cancer at Instituto Nacional de Enfermedades Neoplásicas in Peru between January 2016 and December 2020. Clinical, perioperative, pathological, and survival outcomes were compared between both groups. A propensity score matching method was used to minimize bias. Results: 162 patients were included in the final analysis. 124 had open surgery and 38 had MIS. Patients, clinical tumour, pathological characteristics, and perioperative were similar between groups after matching. Similar circumferential resection margin (CRM) with optimal quality of the mesorectum (p=1.000) but higher number of lymph nodes resected in open surgery group (p=0.741) was described. The leakage rate was slightly higher in the MIS group (p=0.358) with 10.5%, while the postoperative hospital stay was longer in the open surgery group after matching (p=0.001; OR 95% 5.2 CI: 1.8-15.6). The estimated recurrence-free survival (RFS) and overall survival (OS) at 3 years in open surgery and MIS was 71.8% (95% CI; 0.58-0.89) and 70% (95% CI; 0.56-0.88) (p=0.431) and 77.7% (95% CI; 0.64-0.94) and 88.9% (95% CI; 0.79-0.99) (p=0.5), respectively. Conclusions: Shorter postoperative hospital stay in the minimally invasive surgery group was reported. RFS, OS, and re lar between both groups. This approach is for non-metastatic rectal cancer in referral centers in Peru.

We report the case of a 75-year-old female patient with a big tumour in the lower rectum with intestinal obstruction and lower gastrointestinal bleeding history who underwent a tumour biopsy under laparotomy and end colostomy at another hospital in Peru. She came to our institution for clinical evaluation with a pathology result of a rectal gastrointestinal stromal tumour. An extra elevator abdominoperineal resection was performed with tumour-free margins. The histology confirmed a high-grade (G2) rectal gastrointestinal stromal tumour with a mitotic index of 27/50. DOC-1 (+) and CD117 (+) in immunohistochemistry. Genomic DNA was extracted from the paraffin-fixed tumour sample, and c.1504_1509dupGCCTAT (p.Ala502_Tyr503dup) mutation was detected in exon 9 of the KIT gene. Imatinib 400 mg per day for 3 years was indicated as adjuvant treatment. Currently, she has a disease-free survival of 12 months.

BACKGROUND: Gastric cancer (GC) is the second most common cancer and first leading cause of cancer-related deaths in Peru. Infection by Helicobacter pylori (HP) and Epstein-Barr virus (EBV) are accepted carcinogenic and infection is widely spread in the Peruvian population. The aims of this study were to evaluate HP and EBV-associated GC (EBVaCG), to assess the prevalence rate and to define the characteristics of Peruvian patients. METHODS: GC samples were prospectively collected from patients who underwent gastroscopy or surgical resection with no preoperative treatment at INEN between 2015 and 2017. Tumor tissue (T), proximal healthy tissue (P) and distal healthy tissue (D) samples were assessed for HP and EBV by quantitative PCR (qPCR) using specific primers. HP and EBV status were analyzed along with clinicopathologic parameters of the tumor. Kaplan-Meier estimation curves overall survival (OS) was applied. Comparison between qPCR detection and current standard methods of detection was also performed. All tests were two sided, and a p≤0.05 was considered statistically significant. RESULTS: A total of 150 patients were studied with a mean age 65 years and predominance of males (51.3%). Intestinal-mixed histological subtype rate was 72.5% in cases. Most frequent clinical stage was III-IV (74.6%). HP+ patients were determinate with at least one ureA/hspA gene result and EBV+ patients were divided in high viral load (>100copy/μl) and low viral load (<100copy/μl) groups. Results found HP in 87.3% (n=131/150) and EBV in 10% (n=15/150) of the population. Cases and HP concentration were higher in D (ureA: 62.8%, [703.58±245.47pg]; hspA: 73.8%, [42.77±10.17pg]) than P (ureA: 59.0%, [539.69±121.32pg]; hspA: 71.0%, [31.90±8.64pg]) and T (ureA: 49.7%, [296.32±164.98pg]; hspA: 70.5%, [4.6±1.33pg]) (p<.001). High viral load EBV was found in 40% (n=6/15) of cases. Co-infection detection rate was 7.3% (n=11/150). Correlation between qPCR and H&E evaluation of HP was found in only 72.9% (n=19/57) of cases without evidence of HP (p<.001) and no detectable expression of EBV was found by EBER in qPCR positive cases (n= 15). Cases were defined in 4 groups: HP+EBV+ (n=9), HP+EBV- (n=98), HP-EBV+ (n=6), and HP-EBV- (n=37). Results showed median age (67, 66, 67 and 66), most frequent III-IV clinical stage (75%, 69.5%, 72.7% and 62.1%), histologic grade found was GII (50%, 28.8%, 50% and 43.3%) and intestinal-mixed histological subtype (66.6%, 56.6%, 100% and 62.1%) in four groups respectively. EBVaGC was associated to OS (38.3% vs 72.3%) at 1 year, p=0.033). Based on a mean follow-up of 24 months, the 1-year survival was lower in EBV+ [45.5% (HP+ EBV+) and 25% (HP- EBV+)] than in EBV- [73.1% (HP+ EBV-) and 61.5% (HP- EBV-)] groups. CONCLUSION: HP infection is frequent in Peruvian CG patients. Presence of HP and EBV infection evaluated by qPCR define 4 groups with different features and survival. Study supported by CIENCIACTIVA-CONCYTEC, under the contract #196-2015-FONDECYT. Citation Format: Carolina Belmar López, Miluska Castillo Garcia, Carlos A. Castañeda Altamirano, Luis F. Barreda Bolaños, Daniel Valdivia Leonardo, Eduardo Payet Meza, Valeria Villegas Bernaola, Jais Nieves Prado, Joselyn R. Sanchez Sifuentes, Luis A. Bernabé Monsalve, Manuel A. Chumpitaz La Rosa Sanchez, Omar Mejía Dionisio, Ivan Chavez Passiuri. HP and EBVaGC in Peruvian patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4210.

Introduction: Role of TIL and interaction with H. pylori infection is not understood in Gastric Cancer. Methods: Gastric tissue samples were retrospectively collected from 50 patients who were refereed to surgery at Instituto Nacional de Enfermedades Neoplasicas between 2011 and 2012. We prospectively evaluated the distribution and density of tumor-infiltrating lymphocytes (TIL) as well as the presence of H. pylori. An evaluation of the role of the density of different subpopulations of infiltrating immune cells in tissue TMA was additionally performed. Clinicopathological data were collected from medical and pathology reports. Kaplan-Meier estimation curves overall survival (OS) was applied. A p-value ≤0.05 was considered statistically significant. Results: Median age was 52 years and 50% were male, most were HG-3 (83%), Lauren classification (76%) and clinical stage III (50%). Most cases went to subtotal gastrectomy (64%). H. pylori was present in 34% (17/49) and most frequent density was moderate (++) (10/49). Intratumoral TIL mild (92%) and bandlike infiltration (68%). Median percentage of intratumoral CD3, CD4, CD8, CD20, CD68 and CD163 TILs in 5 HPF were 12.00±0.108, 1.55±0.017, 7.96±0.093, 1.34±0.057, 12.30±.054 and 8.88±0.069, respectively. No significant association between immune cell subpopulation density and features was found, however it was a trend to association for: Older age and CD163 (p=0.184), male sex and CD8 (p=0.166) and CD4 (p=0.171), poorly differentiated HG and CD4 (p=0.071), early stage and CD4 (p=0.084), diffuse Lauren classification and CD4 (p=0.13), and H. pylori 0&+/+++ and CD68 (p=0.171). The median follow-up was 4.7 years (CI95%: 4.5-5.0), median survival was 1.7 years (CI95%. 0.6-2.9). Earlier clinical stage (p=0.003), non-lymphatic vascular invasion (p=0.024) and absence of node involvement (p=0.018), early Bormann classification (p=0.030) and absence of metastasis (p=0.029) were associates to survival. In relation to the types of TILs, CD3 (<27.5, p=0.051), CD4 (<2.6, p=0.015), CD8 (>6.2, p=0.049), and CD4/CD8 (<0.31, p=0.006) were associated with poor survival. However, in the Cox model age (>60yr HR: 5.1) Bormann (IV, HR: 22.8), NLR (<2.13, HR: 29.2), LMR (>3.86, HR: 19.8) and CD4/CD8 (<0.31, HR: 10.3) were associated with poor prognosis.Conclusion: Patients with NLR and CD4/CD8 TIL high had better survival. These results suggest the prognostic implications of biomarkers and type of TIL in patients with AGC that could be used in clinical practice. Keywords: Gastric cancer, tumor-infiltrating lymphocytes, H. pylori This study was supported by the CIENCIACTIVA-CONCYTEC, under the contract #197-2015-FONDECYT Citation Format: Carlos Castaneda, Miluska Castillo, Luis Bernabé Monsalve, Joselyn Sanchez Sifuentes, Eduardo Payet Meza, Eloy Ruiz, Fernando Barreda Bolaños, Manuel Chumpitaz La Rosa Sanchez, Brayam Felix, Katherine Tello, Claudio Flores, Carlos Chavez, Ivan Chavez Passiuri. Immune cells in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3793.