Pathological stage significantly predicts survival in colorectal cancer patients: a study from two tertiary care centers in India

Clinical characteristics and survival profile of young versus old colorectal cancer patients at a tertiary cancer center in North India over a period of 5 years

Background

Colorectal cancer (CRC) is mostly considered a disease of the elderly. But the rate is increasing among young adults and is associated with different clinical patterns. The objective was to study the frequency of CRC in young patients and compare the clinicopathological profile and survival with the older cohort.

Methods

Five-year (2012-2016) data of the 912 consecutive CRC cases treated at the center were analyzed. Clinical and histopathological characteristics were compared in young (≤40) and older (>40) patients. Descriptive statistics were used for data presentation. Categorical data were compared by the Chi-square test; survival analyses were performed by Kaplan-Meier method.

Results

In total, 231 (25.3%) and 681 (74.7%) cases were in the young and older age groups, respectively. Male predominance was noted. Young patients presented predominantly in stage III (46%). Majority of the young patients harbored left-sided tumors (75.8% vs 63.7% in old patients, P = 0.001) and rectum was the favored site in young patients (53.7% vs 37%; P < 0.001). Poorly differentiated adenocarcinoma was more common in the young age group (46.88% vs 24.16% in old patients, P < 0.001), also signet-ring cell morphology occurred more often in young patients (11.7% vs 4%, P < 0.001). Survival was inferior in the patients presenting at an advanced stage or with adverse histology or poor tumor grade. However, stage-specific survival showed no significant difference between both groups.

Conclusion

This study shows that though young CRC patients present with higher stage, aggressive morphology, and predominantly rectal localization, the overall survival and stage-specific survival did not differ significantly from the older patients.

Ca2+/nuclear factor of activated T cells signaling is enriched in early-onset rectal tumors devoid of canonical Wnt activation

Our previous extensive analysis revealed a significant proportion of early-onset colorectal tumors from India to be localized to the rectum in younger individuals and devoid of deregulated Wnt/β-catenin signaling. In the current study, we performed a comprehensive genome-wide analysis of clinically well-annotated microsatellite stable early-onset sporadic rectal cancer (EOSRC) samples. Results revealed extensive DNA copy number alterations in rectal tumors in the absence of deregulated Wnt/β-catenin signaling. More importantly, transcriptome profiling revealed a (non-Wnt/β-catenin, non-MSI) genetic signature that could efficiently and specifically identify Wnt- rectal cancer. The genetic signature included a significant representation of genes belonging to Ca²⁺/NFAT signaling pathways that were validated in additional samples. The validated NFAT target genes exhibited significantly higher expression levels than canonical Wnt/β-catenin targets in Wnt- samples, an observation confirmed in other CRC expression data sets as well. We confirmed the validated genes to be transcriptionally regulated by NFATc1 by (a) evaluating their respective transcript levels and (b) performing promoter-luciferase and chromatin immunoprecipitation assays following ectopic expression as well as knockdown of NFATc1 in CRC cells. NFATc1 and its targets RUNX2 and GSN could drive increased migration in CRC cells. Finally, the validated genes were associated with poor survival in the cancer genome atlas CRC expression data set. This study is the first comprehensive molecular characterization of EOSRC that appears to be driven by noncanonical tumorigenesis pathways.

KEY MESSAGES

Early-onset sporadic rectal cancer exhibits DNA gain and loss without Wnt activation. Ca²⁺/NFAT signaling appears to be activated in the absence of Wnt activation. An eight-gene genetic signature distinguishes Wnt+ and Wnt- rectal tumors. NFAT and its target genes regulate tumorigenic properties in CRC cells.