
==== Front
Oncologist
Oncologist
oncolo
The Oncologist
1083-7159
1549-490X
Oxford University Press US

38886182
10.1093/oncolo/oyae153
oyae153
Brief Communication
AcademicSubjects/MED00010
Oncolo/5
Associations with other cancer-related biomarkers might contribute to poor outcomes in RAS-altered, younger patients with colorectal cancer
Kundranda Madappa N Banner MD Anderson Cancer Center, Gilbert, AZ, United States

Kemkes Ariane C Exact Sciences Corporation, Madison, WI, United States

Evans Mark C Exact Sciences Corporation, Madison, WI, United States

Flannery Cynthia A Exact Sciences Corporation, Madison, WI, United States

https://orcid.org/0000-0001-7708-6656
Hall David W Exact Sciences Corporation, Madison, WI, United States

Hoag Jess R Exact Sciences Corporation, Madison, WI, United States

Therala Nishitha Exact Sciences Corporation, Madison, WI, United States

Thakkar Snehal G Exact Sciences Corporation, Madison, WI, United States

De La O Jean-Paul Exact Sciences Corporation, Madison, WI, United States

Corresponding author: Jean-Paul De La O, Exact Sciences Corporation, 5505 Endeavor Lane, Madison, WI, 53719, USA (jdelao@exactsciences.com).
9 2024
17 6 2024
17 6 2024
29 9 e1228e1230
14 2 2024
24 5 2024
© The Author(s) 2024. Published by Oxford University Press.
2024
https://creativecommons.org/licenses/by/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Colorectal cancer (CRC) is a common cancer in younger adults. In patients undergoing liver resection with RAS-altered CRCs, there is evidence suggesting younger patients have worse outcomes than older patients. To explain this pattern, differences in associations between RAS status and other cancer-related biomarkers in tumors from younger versus older patients with CRC were evaluated in a cohort of 925 patients with CRC, 277 (30.0%) of whom were ≤50 years old, and 454 (49.1%) who had RAS-altered tumors. For 3 biomarkers, RNF43, APC, and microsatellite instability (MSI), the association with RAS status was significantly modified by age after adjustment for multiple testing. Specifically, younger patients with RAS-altered tumors were more likely to be MSI-high, RNF43 mutated, and APC wild type. These differences might contribute to the observed pattern of diminished survival in younger versus older patients with CRC with RAS-mutated tumors undergoing liver metastasis resection.

In patients undergoing liver resection with RAS-altered colorectal cancers (CRCs), there is evidence suggesting younger patients have worse outcomes than older patients. To explain this pattern, this study evaluated differences in associations between RAS status and other cancer-related biomarkers in tumors from younger versus older patients with CRC.

colorectal cancer
genetic associations
genomics
RAS
APC
RNF43
MSI-high
Exact Sciences Corporation 10.13039/100030841
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pmcIntroduction

Among younger adults, defined using a cutoff of 50 years, CRC represents the second most common cancer diagnosis and the third leading cause of cancer death.1 CRC in younger adults is characterized by unique clinical, genetic, and epigenetic characteristics, which may affect overall survival compared to CRC diagnosed among older individuals.2 For example, there are notable differences between younger and older patients in the relative frequency of altered driver3 and germline variants.4

Outcomes could differ between younger and older patients with CRC even when genetic alterations are similar. A report of patients with CRC who had undergone surgical resection for liver metastasis noted poorer outcomes if they harbored RAS alterations; but the effect appeared to be more pronounced in younger patients.5 While age per se may be an independent risk factor, the effect could also be attributed to alterations in other cancer-related biomarkers that are associated with RAS alterations in younger patients. To address whether other altered biomarkers might contribute to the pattern of worse outcomes in RAS-altered younger patients versus older patients, we examined the distribution of other altered biomarkers by RAS status and age.

Methods

Tumor samples from patients with metastatic CRC profiled with the tumor-normal, whole-exome, whole-transcriptome OncoExTra assay between April 2018 and July 2022 were included. We focused on DNA alterations deemed to be clinically actionable, defined as: (1) pathogenic within the cancer genome, (2) associated with an FDA-approved therapy, (3) an eligibility criterion for clinical trial enrollment, or (4) deemed significant based on recent literature review.

Associations between RAS status and other biomarker alterations were examined by age group (≤50 years vs >50 years). Differences in associations between patients ≤50 years versus >50 years were tested using the Breslow-Day (B-D) statistic, which tests the homogeneity of odds ratios (ORs). We restricted our analysis to biomarkers that were altered in at least 10 patients to maintain minimal sample sizes for statistical testing and clinical relevance, and adjusted P-values for the false discovery rate, to give Q-values, to account for multiple testing. The significance threshold was set to 0.05. All analyses were performed using SAS software (version 9.4, SAS Institute, Cary, NC).

Results

There were 925 metastatic CRC patient samples analyzed; 454 (49.1%) were RAS altered and 471 (50.9%) were RAS wild type. The majority of RAS alterations were at KRAS (n = 419, 92.3%), and the remainder were at NRAS (n = 35, 7.7%). No HRAS alterations were seen. Most patients were age >50 years (n = 648, 70.0%), and RAS status did not differ by age (RAS altered 48.4% ≤50 years vs 49.4% >50 years, P = .78). We observed alterations at 169 non-RAS genes, and 49 of these were altered in 10 or more tumor samples. Tumor mutational burden (TMB) was high (≥10 mut/Mb) in 82 samples (8.9%) and microsatellite instability (MSI) was high in 60 (6.5%) samples; all samples that showed MSI-high were also TMB-high. A summary of these 51 altered biomarkers (49 genes, TMB, and MSI) and their associations with RAS status by age are provided in Supplementary Table S1.

The association with RAS status was significantly modified by age after adjustment for multiple testing for 3 biomarkers (RNF43, MSI-High, and APC; Table 1). Both RNF43-altered and MSI-high biomarkers were more prevalent in RAS-altered younger patients. A total of 8.2% of patients ≤50 years had both RAS and RNF43 alterations, compared to 2.8% of patients >50 years. Among patients ≤50 years, a positive yet nonsignificant association was observed between RNF43-altered status and RAS-altered status (OR: 2.47, 95% CI, 0.83-7.30, P = .12); however, among patients >50 years, the odds of being RAS altered were significantly lower for RNF43-altered versus RNF43-wild type patients (OR: 0.24, 95% CI, 0.11-0.51, P < .001; B-D test, P < .001). A similar pattern was observed for the association between RAS status and MSI-high by age (B-D test, P = .002). In contrast, APC alterations were less frequent in RAS-altered younger patients (67.9%) compared to older patients (82.8%) or, equivalently, unaltered (wild type) APC was more frequent. Among patients ≤50 years there was a nonsignificant negative association between APC-altered status and RAS-altered status (OR: 0.74, 95% CI, 0.44-1.24, P = .25); however, among patients >50 years, the odds of being RAS altered was significantly higher for APC altered versus APC wild type (OR: 1.96, 95% CI, 1.35-2.86, P < .001; B-D test, P = .003).

Table 1. Distribution of biomarkers exhibiting a significantly different association with RAS status in younger versus older adults, as determined by the B-D test, after correcting for the false discovery rate.

Biomarker
	Age ≤ 50 years (n = 277)	Age > 50 years (n = 648)	B-D
P-value
	B-D
Q-value
	
RAS WT (n = 143)	RAS alt (n = 134)	RAS WT (n = 328)	RAS alt (n = 320)	
RNF43 WT (n = 865)	138	123	293	311			
RNF43 alt (n = 60)	5	11	35	9			
	OR = 2.47 (CI, 0.83-7.30)	OR = 0.24 (CI, 0.11-0.51)	<.001	.012	
Not MSI-High (n = 865)	138	123	296	308			
MSI-High (n = 60)	5	11	32	12			
	OR = 2.47 (CI, 0.83-7.30)	OR = 0.36 (CI, 0.18-0.71)	.002	.048	
APC WT (n = 230)	37	43	95	55			
APC alt (n = 695)	106	91	233	265			
	OR = 0.74 (CI, 0.44-1.24)	OR = 1.96 (CI, 1.35-2.86)	.003	.048	
Within each age group, for each biomarker the OR for an association and its 95% CI are shown; CIs that do not overlap 1.0 are bolded.

Abbreviations: B-D, Breslow-Day; WT, wild type (no somatic mutation); alt, altered; OR, odds ratio.

Conclusions

In this study, we discovered that RNF43, when altered, APC, when wild type, and MSI-high appear to be more prevalent in RAS-altered tumors from younger patients with CRC. Could such a finding help to explain the poorer prognosis observed in RAS-altered younger patients compared to RAS-altered older patients undergoing liver resection?

There is evidence that all 3 of these biomarkers are prognostic for outcome in patients with CRC. Specifically, APC-wild type status is associated with poor response to chemotherapy, resulting in shorter overall survival.6 While MSI-high CRC tumors generally have more favorable outcomes, they are resistant to chemotherapy.7 Finally, patients with CRC with RNF43-altered tumors have poorer relapse-free survival8 and worse overall survival.9 Thus, it is possible that the associations observed, with biomarkers prognostic for poor outcome overrepresented in RAS-altered younger patients, could contribute to the observed pattern.

However, the frequency of APC wild type, RNF43 altered, and MSI in younger patients with RAS-mutated tumors is only 5%-15% greater than in older patients, which may be insufficient to fully explain the observed 20% overall survival hazard ratio difference,5 even if the effects of these biomarkers on survival were substantial. It would be informative to examine the clinical outcomes for younger patients with CRC with RAS-mutated tumors who are APC wild type, RNF43 altered, or have MSI tumors.

Nevertheless, our findings suggest that higher-order associations among biomarkers, RAS status and age are present in CRC tumors and may thus be a contributing factor to the apparent difference in outcome between RAS-altered younger and older patients with CRC after liver resection. Such higher-order genetic associations suggest that tumor profiling should be comprehensive, assaying multiple genes, as focusing on one or a few genes may fail to identify important prognostic biomarkers that could help to inform therapy decisions. The prevalence of these multibiomarker associations that differ by age of onset should be further investigated in CRC and other cancers.

Limitations of our study include the moderate sample size, and the lack of clinical data to confirm the RAS status and age interaction on outcomes following liver resection in this cohort.

Supplementary material

Supplementary material is available at The Oncologist online.

oyae153_suppl_Supplementary_Table

Acknowledgments

We would like to thank Purva Singla and Matt Petitt for feedback.

Author contributions

Madappa N. Kundranda (Conceptualization, Investigation, Project administration, Writing—original draft, Writing—review & editing), Ariane C. Kemkes (Data curation, Writing—review & editing), Mark C. Evans (Data curation, Formal Analysis, Writing—review & editing), Cynthia A. Flannery (Data curation, Formal Analysis, Writing—review & editing), David W. Hall (Investigation, Methodology, Writing—original draft, Writing—review & editing), Jess R. Hoag (Data curation, Formal Analysis, Investigation, Methodology, Writing—original draft, Writing—review & editing), Nishitha Therala (Validation, Writing—review & editing), Snehal G. Thakkar (Conceptualization, Investigation, Project administration, Writing—original draft, Writing—review & editing), and Jean-Paul De La O (Conceptualization, Writing—review & editing)

Funding

This research was sponsored and funded by Exact Sciences Corporation.

Conflicts of interest

A.C.K., M.C.E., C.A.F., D.W.H., J.R.H., N.T., S.G.T., and J.-P.D.L.O. are employees of Exact Sciences Corporation.

Data availability

The data underlying this article are available in the article and in Supplementary Table S1.
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