This study aimed to estimate the incidence of KRAS, NRAS, and BRAF mutations in the Moroccan population, and investigate the associations of KRAS and NRAS gene mutations with clinicopathological characteristics and their prognosis value. To achieve these objectives, we reviewed medical and pathology reports for 210 patients. RAS testing was investigated by Sanger sequencing and Pyrosequencing technology. BRAF (exon 15) status was analyzed by the Sanger method. The expression of MMR proteins was evaluated by Immunohistochemistry. KRAS and NRAS mutations were found in 36.7% and 2.9% of 210 patients, respectively. KRAS exon 2 mutations were identified in 76.5% of the cases. RAS-mutated colon cancers were significantly associated with female gender, presence of vascular invasion, classical adenocarcinoma, moderately differentiated tumors, advanced TNM stage III-IV, left colon site, higher incidence of distant metastases at the time of diagnostic, microsatellite stable phenotype, lower number of total lymph nodes, and higher means of positive lymph nodes and lymph node ratio. KRAS exon 2-mutated colon cancers, compared with KRAS wild-type colon cancers were associated with the same clinicopathological features of RAS-mutated colon cancers. NRAS-mutated patients were associated with lower total lymph node rate and the presence of positive lymph node. Rare RAS-mutated tumors, compared with wild-type tumors were more frequently moderately differentiated and associated with lower lymph node rate. We found that KRAS codon 13-mutated, tumors compared to codon 12-mutated tumors were significantly correlated with a higher death cases number, a lower rate of positive lymph, lower follow-up time, and poor overall survival. Our findings show that KRAS and NRAS mutations have distinct clinicopathological features. KRAS codon 13-mutated status was the worst predictor of prognosis at all stages in our population.

Background Tumors with microsatellite instability (MSI tumors) have distinct clinicopathological features. However, the relation between these tumor subtypes and survival in colon cancer remains controversial. The aim of this study was to evaluate the overall survival (OS) in patients with MSI phenotype, in FES population. Methods The expression of MMR proteins was evaluated by immunohistochemistry for 330 patients. BRAF, KRAS, and NRAS mutations were examined by Sanger sequencing and pyrosequencing methods. The association of MSI status with a patient's survival was assessed by the Kaplan–Meier method and log-rank test. Results The mean age was 54.6 years (range of 19-90 years). The MSI status was found in 11.2% of our population. MSI tumors were significantly associated with male gender, younger patients, stage I-II, right localization, and a lower rate of lymph node and distant metastasis. The OS tends to be longer in MSI tumors than MSS tumors (109.71 versus 74.08), with a difference close to significance (P = 0.05). Conclusion Our study demonstrates that MSI tumors have a particular clinicopathological features. The results of survival analysis indicate that the MSI status was not predictive of improved overall survival in our context with a lower statistical significance (P = 0.05) after multivariate analysis.

Pathologic features depending on tumor response to preoperative chemoradiotherapy are important to determine the outcomes in patients with rectal cancer. Evaluating the potential predictive roles of biomarker expression and their prognostic impact is a promising challenge. We reported here the immunohistochemical staining of a panel marker of mismatch repair protein (MMR), Ki67, HER-2, and p53. Additionally, identification of somatic mutations of KRAS, NRAS, and BRAF genes were performed by direct sequencing and pyrosequencing in pretreated biopsy tissues from 57 patients diagnosed for rectal cancer. Clinical features and pathological criteria for postneoadjuvant treatment surgical resection specimen’s data were collected. Immunohistochemical expression and mutational status were correlated with therapeutic response, overall survival, and disease progression. The mean age of patients was 56 years. Seven (12.3%) out of 57 patients had a complete therapeutic response. Our analysis showed that when using complete therapeutic response (Dworak 4) and incomplete therapeutic response (Dworak 3, 2, and 1) as grouping factor, high p53 expression at the pretreatment biopsy was significantly associated to an incomplete response (p=0.002). For 20 and 2 out of 57, KRAS and NRAS mutations were detected, respectively. The majority of these mutations affected codon 12. KRAS mutations detected at codon 146 (A146T, A146V) was associated with the appearance of recurrence and distant metastasis (p=0.019). A high expression of HER-2 corresponding to score 3+ was observed in 3 pretreatment biopsy specimens. This class was significantly associated with a short relapse-free survival (p=0.002). Furthermore, the high expression of Ki67 was moderately correlated with an older age (p=0.016, r=0.319). In addition, this shows that high p53 expression in the pretreatment biopsy was associated with an incomplete response in surgical resection specimens after neoadjuvant treatment, and a HER-2 score 3+ can be a predictive factor of distant metastasis and local recurrence. Larger, prospective, and more studies are needed.

Background. Tumor budding is now emerging as one of the robust and promising histological factors that play an important role in colon cancer. In this study, we aimed to investigate the association between tumor budding and tumor clinicopathological factors, tumor molecular signature, and patient survival for the first time in a Moroccan population. Methods. We collected data of 100 patients operated from colon adenocarcinoma. Tumor budding was assessed on HES slides, according to the International Tumor Budding Consensus Conference 2016 recommendations. The expression of MMR proteins was performed by immunohistochemistry. KRAS and NRAS mutations testing was performed by Sanger sequencing and pyrosequencing. Results. High tumor budding grade (BUD 3) was found to be significantly associated with adverse clinicopathological features including older age ( P = 0.03 ), presence of perineural invasion ( P = 0.02 ), presence of vascular invasion ( P = 0.05 ), distant metastases ( P < 0.001 ), advanced TNM stage ( P = 0.001 ), the occurrence of relapse ( P = 0.04 ), and the high number of deceased cases ( P = 0.02 ). Interestingly, we found that tumors with high-grade tumor budding were more likely to be microsatellite stable (MSS) ( P = 0.005 ) and harbor more KRAS mutations ( P = 0.02 ). Tumors with high-grade tumor budding were strongly associated with KRAS G12D mutation ( P = 0.007 ). In all stages, high tumor budding was correlated with poorer overall survival ( P = 0.04 ) and decreased relapse-free survival with a difference close to significance (( P = 0.09 ). We concluded that high tumor budding was strongly associated with unfavorable clinicopathological features and special molecular biomarkers and effectively affects the overall survival of CC patients. Conclusions. Based on these findings and the ITBCC group recommendations, tumor budding should be taken into account along with other clinicopathologic factors in the risk assessment of colorectal cancer.

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