Evaluation of Prognostic Factors for Survival in Transverse Colon Cancer

Concurrent RAS and RAS/BRAF V600E Variants in Colorectal Cancer: More Frequent Than Expected? A Case Report

The assessment of RAS and BRAF mutational status is one of the main steps in the diagnostic and therapeutic algorithm of metastatic colorectal cancer (mCRC). Multiple mutations in the BRAF and RAS pathway are described as a rare event, with concurrent variants in KRAS and BRAF genes observed in approximately 0.05% of mCRC cases. Here, we report data from a case series affected by high-risk stage III and stage IV CRC and tested for RAS and BRAF mutation, treated at our Medical Oncology Unit. The analysis of KRAS, NRAS (codons 12, 13, 59, 61, 117, 146), and BRAF (codon 600) hotspot variants was performed in 161 CRC tumors from August 2018 to September 2021 and revealed three (1.8%) patients showing mutations in both KRAS and BRAF (V600E), including two cases with earlier CRC and one with metastatic disease. We also identified one patient (0.6%) with a mutation in both KRAS and NRAS genes and another one (0.6%) with a double KRAS mutation. Notably, the latter was characterized by aggressive behavior and poor clinical outcome. The mutational status, pathological features, and clinical history of these five CRC cases are described. Overall, this study case series adds evidence to the limited available literature concerning both the epidemiological and clinical aspects of CRC cases characterized by the presence of concurrent RAS/BRAF variants. Future multicentric studies will be required to increase the sample size and provide additional value to results observed so far in order to improve clinical management of this subgroup of CRC patients.

Prognostic Factors for Survival in Transverse Colon Cancers

BACKGROUND

Transverse colon cancer (TCC) is a rare condition that accounts for 10% of all colon cancers. TCC was accepted more likely right-sided colon cancers. We aimed to investigate whether TCC differs from other colon tumors by using clinical, pathological, and molecular prognostic factors known to be important in colon cancer and if it differs in its own anatomical structure.

PATIENTS AND METHODS

We evaluated local and locally advanced TCC patients between 2007 and 2020 years for demographics data, symptoms, treatment status, and histopathological and molecular features.

RESULTS

Overall, 107 TCC patients were included in this study. According to the molecular data analysis of 44, 35, and 23 patients for MSI, RAS, and BRAF status, respectively, 7 (15.9%) were MSI-H, 13 (37.1%) were RAS mutant, and 11 (47.8%) had BRAF V600E mutation. The median follow-up time was 31.5 months. Median disease-free survival (DFS) was 5.19 months, and median OS was 88.3 months for the whole study population. The tumor stage was the most significant prognostic factor for DFS and OS. Although BRAF mutation was not a significant marker for DFS, it was an independent prognostic marker for OS (HR 3.90 95% CI 1.42-10.7). There were no statistically significant differences between proximal two-thirds and distal one-third tumor location.

CONCLUSION

TCC has molecular features and prognostic factors more likely RCC and no differences between proximal and distal sub-parts. BRAF V600E mutation status is an independent predictor of survival even in the early stages of TCC.