https://orcid.org/0009-0006-3189-5160
Figures
Abstract
The prognostic significance of KRAS and BRAF mutations is well-established in metastatic colorectal cancer (CRC) but remains uncertain in early-stage tumors. This study retrospectively analyzed 47 stage II/III CRC patients undergoing curative surgery to assess the association of mutations in KRAS, NRAS, BRAF, and PIK3CA with overall survival (OS) and disease-free survival (DFS). Additionally, a meta-analysis was conducted to validate the prognostic relevance of these gene mutations. We included post hoc analyses of phase III randomized controlled trials (RCTs) in stage II/III patients receiving adjuvant therapy after curative resection in the meta-analysis. Pooled hazard ratio (HR) and 95% confidence interval (CI) was calculated using a random-effect model in the overall population, stratified subgroups adjusted for microsatellite instability (MSI) status, and within MSI-high (MSI-H) and microsatellite-stable (MSS) populations. In the retrospective cohort, mutations in KRAS, NRAS, BRAF, and PIK3CA were identified in 29.8%, 4.3%, 8.5%, and 14.9% of patients, respectively. No significant association between individual genes and survival was observed. However, in MSS patients, concurrent mutations were significantly associated with shorter OS and DFS (log-rank test, P < 0.05). The meta-analysis incorporated 13 eligible studies, including 15,034 patients. Pooled analyses revealed that KRAS and BRAF mutations were significantly linked to poor OS (KRAS: HR = 1.25, 95%CI: 1.06-1.47, P = 0.008; BRAF: HR = 1.43, 95%CI: 1.26-1.63, P < 0.001) and DFS (KRAS: HR = 1.36, 95%CI: 1.21-1.53, P < 0.001; BRAF: HR = 1.21, 95%CI: 1.02-1.44, P = 0.032). The prognostic impact of BRAF mutation increased with MSI adjustment compared those without MSI adjustment. In MSS tumors, KRAS-mutant patients demonstrated significantly shorter DFS (HR = 1.63, 95%CI: 1.25-2.13, P < 0.001), while BRAF-mutant patients exhibited reduced OS (HR = 1.53, 95%CI: 1.24-1.89, P < 0.001) and DFS (HR = 1.72, 95%CI: 1.20-2.46, P = 0.003) compared to wildtype patients. Conversely, no significant survival differences were found between mutant and wildtype patients in the MSI-H population. Although PIK3CA mutation was nominally associated with OS (HR = 0.86, 95%CI: 0.75-1.00, P = 0.046), the pooled result lacked robustness. In conclusion, KRAS and BRAF mutations had a negative prognostic impact on MSS stage II/III CRC patients receiving adjuvant therapy following curative resection. These patients may benefit from more effective adjuvant treatment strategies.
Citation: Kang D, Li J, Li Y, Xu J, Yang J, Zhang Z (2025) Prognostic significance of KRAS, NRAS, BRAF, and PIK3CA mutations in stage II/III colorectal cancer: A retrospective study and meta-analysis. PLoS ONE 20(4): e0320783. https://doi.org/10.1371/journal.pone.0320783
Editor: Shiki Fujino,, Osaka International Cancer Institute: Osaka Kokusai Gan Center, JAPAN
Received: October 12, 2024; Accepted: February 25, 2025; Published: April 25, 2025
Copyright: © 2025 Kang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the manuscript and its Supporting Information files.
Funding: The author(s) received no specific funding for this work.
Competing interests: The authors have declared that no competing interests exist.
Introduction
Colorectal cancer (CRC) is the most common malignancy of the digestive tract, ranking as the third most prevalent cancer worldwide and the second leading cause of cancer-related mortality [1]. In China, both the incidence and mortality rates of CRC have been steadily increasing [2]. In 2010, there were 274800 newly diagnosed CRC cases and 132100 CRC-related deaths [3]. It is estimated that by 2025, these numbers will rise 642300 new cases and 221100 deaths [4].
Tumor staging remains the most crucial prognostic factor for CRC. For patients with stage III or high-risk stage II CRC, adjuvant chemotherapy following curative resection is the standard protocol that significantly reduces the risk of recurrence and mortality [5–7]. However, even among patients with the same tumor stage, prognosis can vary widely [8]. The identification of various genetic alterations in CRC highlights the importance of establishing reliable genetic prognostic markers to guide treatment strategies and improve both survival rates and quality of life [9, 10].
Aberrant activation of the RAS-RAF-MAPK and PI3K-PTEN-AKT pathways promotes tumor cell proliferation, invasion, metastasis, and angiogenesis. Mutations in pathway-related genes, such as KRAS, NRAS, BRAF, and PIK3CA, influence treatment responses and serve as key prognostic indicators in cancer treatment [11, 12]. In metastatic colorectal cancer (mCRC), KRAS and BRAF mutations are well-known markers of resistance and poor prognosis in patients receiving anti-epidermal growth factor receptor (EGFR) monoclonal antibodies [13–16]. However, the prognostic value of these mutations in patients with stage II/III CRC undergoing curative surgery followed by adjuvant chemotherapy remains controversial. For instance, a post hoc analysis of the phase III CALGB 89803 trial by Ogino et al. found no significant association between KRAS mutation and overall survival (OS) or disease-free survival (DFS), although BRAF mutation was linked to shorter OS [17]. Analyses of the NSABP C-07 and C-08 phase III trials by Gavin et al. produced similar results [18]. In contrast, post hoc analyses of the NCCTG N0147 and PETACC-8 trials indicated that KRAS mutation was significantly associated with worse OS and DFS [19,20].
In this retrospective study, we evaluated the prognostic value of KRAS, NRAS, BRAF, and PIK3CA mutations in Chinese patients with stage II/III CRC. Additionally, we conducted a systematic review and meta-analysis to assess the prognostic significance of these gene mutations in stage II/III CRC patients who received adjuvant chemotherapy following curative surgery.
Materials and methods
Participants
This retrospective study included CRC patients who underwent curative resection surgery at Tianjin Third Central Hospital, Tianjin, China between December 2019 and March 2022. Patients were eligible for analysis if they had a confirmed diagnosis of stage II and III CRC according to the 8th Edition of the American Joint Committee on Cancer (AJCC) and complete clinical, pathological, and survival data. Exclusion criteria included: (1) prior chemotherapy, radiotherapy, or targeted therapy before surgery; (2) familial adenomatous polyposis or Lynch syndrome; and (3) colorectal tumor metastasized from tumors in other organs. The date when data were accessed for research purposes was 10/7/2024. All researchers had no access to information that could identify individual participants during or after data collection. A total of 47 stage II/III CRC patients were included in this study. The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Tianjin Third Central Hospital. Written informed consent was obtained from all patients. The raw data of this retrospective analysis were supplied in S1 Data.
Analysis of KRAS, NRAS, BRAF, PIK3CA, and MSI status
Mutation status of KRAS, NRAS, BRAF, and PIK3CA genes was determined from genomic DNA extracted from formalin-fixed, paraffin-embedded (FFPE) samples using the QIAamp DNA FFPE Tissue Kit (Qiagen, Germany). Targeted next-generation sequencing (NGS) was performed using a pan-cancer panel covering all exons and critical introns of 616 cancer-related genes. DNA (50-100ng) was used for library construction with the MGIEasy Universal DNA Library Kit (MGI, China), followed by hybrid capture using an xGen Hybridization and Wash Kit (IDT, USA). Libraries were sequenced with 2 × 100 bp paired-end reads on the MGISEQ-2000 (MGI, China) platform. Sequencing data were processed to detect single nucleotide variations (SNVs) and short insertions and deletions (indels). Reads were aligned to the human reference genome GRCh37/hg19 using BWA-MEM v0.7.17. VarScan v 2.4.3 was used to call SNVs and indels, requiring at least 5 supporting reads for indels and 8 supporting reads for SNVs.
Microsatellite instability (MSI) status was assessed using six monomorphic mononucleotide markers (NR-21, BAT-26, NR-27, BAT-25, NR-24, MONO-27). Tumors were classified as MSI-high (MSI-H) if two or more markers were unstable, and microsatellite stable (MSS) if fewer than two markers were unstable.
Literature search and selection process for meta-analysis
To evaluate the prognostic value of KRAS, NRAS, BRAF, and PIK3CA mutations in stage II and III CRC patients receiving adjuvant therapy post-surgery, a preferred reporting items for systematic reviews and meta-analyses (PRISMA)-compliant meta-analysis was conducted (S1 Checklist) [21]. Only post hoc analyses from phase III randomized controlled trials (RCTs) were included, while observational studies were excluded to minimize biases related to mutation detection, patient selection, adjuvant therapy, and selective reporting. A comprehensive literature search was conducted using PubMed, EMBASE, Web of Science, and the Cochrane Library, covering studies published until June 30, 2024. Search strategies for these databases are detailed in S1 Table. Only articles in English were considered, and reference lists of relevant studies were manually reviewed for additional eligible publications.
The eligibility of studies retrieved from literature search was assessed using the PICOS framework: Participants (P) were stage II and III CRC patients receiving adjuvant therapy post-resection; Intervention (I) was the presence of KRAS, NRAS, BRAF, or PIK3CA mutations; Control (C) was wild-type status for these genes; Outcomes (O) were OS and DFS; Study design (S) was post-hoc analysis of phase III RCTs. Observational studies, reviews, case series, studies of advanced tumors or mixed stages (I–IV), and those lacking sufficient prognostic data were excluded. For multiple post-hoc analyses from the same trial, only the analysis with the most complete data was included. The process of literature search and selection is shown in Fig 1.
Quality assessment and data extraction
Study quality was assessed using the Newcastle-Ottawa Scale (NOS) for cohort studies [22]. A maximum of 9 stars was awarded based on selection, comparability, and outcome categories. Studies with 7 or more stars were considered high quality, those with 5 or 6 stars moderate quality, and those with 4 or fewer stars low quality.
The following information was extracted: first author, publication year, trial name, adjuvant therapy, cancer type, tumor stage, number of patients analyzed, number of KRAS, NRAS, BRAF or PIK3CA-mutant patients, follow-up duration, and hazard ratios (HRs) with 95% confidence interval (CIs) for OS and DFS. OS was defined as the time from randomization to death from any cause or the last follow-up. DFS was defined as the time from assignment to cancer recurrence, the occurrence of a new colorectal tumor, death from any cause, or last follow-up. When available, HRs from multivariate analysis adjusted for MSI status were prioritized; otherwise, HRs from univariate analysis were used. Relapse-free survival (RFS) was considered equivalent to DFS.
Two independent authors (DK, JL) conducted the literature search and selection, data extraction, and quality assessment. Discrepancies were resolved through discussion with a third author (JY).
Statistical analysis
In the retrospective analysis, categorical variables were compared using the chi-square test or Fisher’s exact test. Kaplan-Meier (KM) survival curves were generated, and survival differences were evaluated using the log-rank test. In addition to single gene mutation, the impact of concurrent mutations defined as simultaneous mutations in at least two of these four genes on survival was analyzed. Univariate and multivariate Cox regression analyses were conducted to calculate HR and 95%CI. For the meta-analysis, between-study heterogeneity was assessed using the I2 statistic. A random-effects model was applied for pooled analyses, regardless of heterogeneity, to generate more conservative estimates than a fixed-effects model. Pooled HRs with 95%CIs were calculated to assess the prognostic impact of KRAS, NRAS, BRAF and PIK3CA mutations on survival outcomes. Subgroups analyses were conducted based on whether HR estimates were adjusted for MSI status. Studies performing multivariate analysis with adjustment of MSI status were included in the subgroup with MSI adjustment. Studies only conducting univariate analysis or performing multivariate analysis without adjustment of MSI status were included in the subgroup without MSI adjustment. Further analyses were performed separately in MSI-H and MSS patients. Sensitivity analyses, using a leave-one-out mothed, were conducted by omitting one study at a time to assess the robustness of the results. Funnel plots and Egger’s tests were applied to detect potential publication bias. All statistical analyses were conducted using STATA 16.0 (StataCorp, US). P value < 0.05 was considered statistically significant.
Results
Prognostic value of KRAS, NRAS, BRAF and PIK3CA mutations in retrospective analysis
In the cohort of 47 CRC patients, 29 (61.7%) were male, and 20 (38.3%) were female, with ages ranging from 37 to 84 years and a mean age of 62.9 years. Twenty-six (55.3%) patients had stage II tumor, and 21 (44.7%) had stage III tumor. The resection margins of all patients were microscopically clear of malignant cells (R0 resection). The median number of harvested lymph nodes was 19 (interquartile range: 12-26). As shown in Table 1, the mutation rates of KRAS, NRAS, BRAF, and PIK3CA were 29.8%, 4.3%, 8.5%, and 14.9%, respectively. Four patients had concurrent KRAS and PIK3CA mutations, and one had concurrent BRAF and PIK3CA mutations. The mutation distribution is shown in S2 Table. Regarding MSI status, there were 4 MSI-H and 43 MSS patients. The clinicopathological features were similar between KRAS mutant and wildtype patients except for tumor location (Table 1). KRAS mutations were more frequently detected in the right-sided tumor than left-sided tumor (P = 0.026).
The median follow-up was 35.3 months (range: 6.4-68.4 months). Cox regression analysis demonstrated that tumor stage was an independent factor for DFS (S3 Table). No significant correlation between gene mutations and survival outcomes was observed. We performed additional survival analyses in 43 MSS patients (S4 Table). KRAS mutations were not significantly associated with OS or DFS (Fig 2A). Univariate analysis showed that patients with concurrent mutations had significantly worse OS and DFS compared to those with single or no mutations (log-rank test P < 0.05, Fig 2B).
(A) KRAS mutation; (B) Concurrent mutations in KRAS, NRAS, BRAF, and PIK3CA.
Baseline characteristics of studies included in meta-analysis
A total of 2490 records were identified through the literature search (Fig 1). After screening title, abstract, and full text, 13 eligible studies with a total of 15034 patients were included in the meta-analysis (S5 Table). These studies performed post-hoc analyses of phase III trials, including Intergroup 0135/NCCTG 91-46-53/NCIC CTG CO.9 [23], QUASAR [24], CALGB 89803 [17,25], NSABP C-07 and C-08 [18], PETACC-3 [26], ACTRN12610000509066 [27], NCCTG N0147 [19], MOSAIC [6], PETACC-8 [20], QUASAR2 [28], JCOG0910 [29], and CALGB/SWOG 80702 [30]. KRAS mutation status was analyzed in 9 studies, involving 11,818 CRC patients, of whom 4183 had KRAS mutations. The prognostic significance of BRAF mutation status was assessed in 11 studies, comprising 13210 CRC cases and 1418 BRAF-mutant individuals. Five studies assessed the association between PIK3CA mutation status and survival outcomes, with 5095 CRC patients and 961 PIK3CA-mutant individuals [18,25,28–30]. Only three studies, with 3271 cancer patients and 89 NRAS-mutant individuals, analyzed the association between NRAS mutation status and survival [18,28,29]. Seven trials adjusted for MSI status in their HR estimates [17,19,20,25,26,28,30]. Among these studies, one performed separate survival analysis in both MSI-H and MSS populations [20] and one study in MSS population [28]. Among the other studies that did not adjust for MSI status, three performed separate survival analyses in both MSI-H and MSS populations [20,23,24]. The baseline characteristics of included studies were summarized in Table 2. According to NOS assessment, all studies were considered to have high quality (S6 Table). The extracted data for quantitative analysis are shown in S2 Data.
Prognostic value of KRAS mutations in meta-analysis
The pooled analysis showed that KRAS mutations were significantly associated with worse OS (HR = 1.25, 95%CI: 1.06-1.47, P = 0.008, Fig 3A) and DFS (HR = 1.36, 95%CI: 1.21-1.53, P < 0.001, Fig 3B). In the subgroup with MSI adjustment, the associations remained significant (OS: HR = 1.29, 95%CI: 1.04-1.61, P = 0.019; DFS: HR = 1.37, 95%CI: 1.12-1.67, P = 0.002). In the subgroup without MSI adjustment, KRAS mutation status was significantly associated with DFS (HR = 1.32, 95%CI: 1.16-1.48, P < 0.001) but not with OS (HR = 1.12, 95%CI: 0.95-1.31, P = 0.180).
One study performed separate OS analyses in MSI-H and MSS populations [20], showing that KRAS mutation was significantly related with worse OS in MSS patients (HR = 1.71, 95%CI: 1.21-2.41) but not in MSI-H patients (HR = 0.90, 95%CI: 0.23-3.45). In terms of DFS (Fig 4), pooled analysis demonstrated that KRAS mutation status was a prognostic factor in the MSS population (HR = 1.63, 95%CI: 1.25-2.13, P < 0.001), but not in the MSI-H population (HR = 0.99, 95%CI: 0.45-2.14, P = 0.973).
Prognostic value of BRAF mutations in meta-analysis
Meta-analysis revealed that BRAF mutations were significantly associated with worse OS (HR = 1.43, 95%CI: 1.26-1.63, P < 0.001, Fig 5A) and DFS (HR = 1.21, 95%CI: 1.02-1.44, P = 0.032, Fig 5B). In the subgroup with MSI adjustment, BRAF-mutant patients had significantly worse OS (HR = 1.59, 95%CI: 1.32-1.92, P < 0.001) and DFS (HR = 1.43, 95%CI: 1.16-1.76, P = 0.001) compared to wildtype patients. In the subgroup without MSI adjustment, BRAF mutations were significantly associated with OS (HR = 1.31, 95%CI: 1.07-1.59, P = 0.007) but not DFS (HR = 0.98, 95%CI: 0.83-1.16, P = 0.832).
As shown in Fig 6, BRAF mutation status was a prognostic factor in MSS population (OS: HR = 1.53, 95%CI: 1.24-1.89, P < 0.001; DFS: HR = 1.72, 95%CI: 1.20-2.46, P = 0.003), but not in MSI-H population (OS: HR = 0.69, 95%CI: 0.08-5.94, P = 0.734; DFS: HR = 0.82, 95%CI: 0.26-2.56, P = 0.731).
Prognostic value of NRAS and PIK3CA mutations in meta-analysis
None of the trials evaluating NRAS mutations had adjusted for MSI status. NRAS mutations were not significantly associated with survival outcomes (S1 Fig). PIK3CA mutation was associated with favorable DFS at marginal significance (HR = 0.86, 95%CI: 0.75-1.00, P = 0.046, S2 Fig). However, no association between PIK3CA mutation and OS was found (HR = 0.91, 95%CI: 0.77-1.08, P = 0.266, S3 Fig).
Sensitivity analysis and publication bias
Sensitivity analysis showed that omitting Domingo’s study reduced between-study heterogeneity of meta-analysis of BRAF mutation associated with DFS from 46.1% to 0% [28]. The association remained significant (HR = 1.14, 95%CI: 1.02-1.29, P = 0.027). In the analysis of PIK3CA on DFS, the association became insignificant (HR = 0.90, 95%CI: 0.76-1.05, P = 0.155) after excluding Nowak’s study [30]. No potential publication bias was observed in the analyses of KRAS and BRAF mutations (S4 Fig).
Discussion
In the retrospective cohort, we did not observe a significant association between individual genes including KRAS, BRAF, NRAS, and PIK3CA and the survival outcomes of stage II/III CRC patients, possibly due to the small sample size. Notably, in patients with MSS tumors, concurrent mutations were associated with a poor prognosis. To confirm the prognostic value of these mutations, we conducted a meta-analysis by pooling post hoc analyses of phase III RCTs in stage II/III patients undergoing adjuvant therapy after surgery. The pooled analysis demonstrated that KRAS and BRAF mutations were significantly associated with worse OS and DFS. The prognostic significance was further modified by MSI status, with unfavorable prognoses observed only in MSS patients and not in those with MSI-H tumors.
The RAS-RAF-MAPK signaling pathway play a crucial role in regulating cell growth, differentiation, proliferation, and survival. Mutations in pathway-related genes, such as KRAS, NRAS, and BRAF, result in abnormal downstream signaling that drives uncontrolled cell growth, thereby contributing to tumorigenesis. The mutation frequency of KRAS in CRC is 35-45%, with the most common mutations occurring at codons 12 and 13 in exon 2, while fewer mutations are observed at codon 61 and codon 146 [31]. NRAS mutations are less frequent, occurring in 1-7% of cases [32,33]. BRAF mutations occur in 2-15% of CRC cases, with the V600E mutation accounting for over 90% of these mutations [34]. PIK3CA, another oncogene frequently mutated in CRC, contributes to cancer progression by activating the PI3K-AKT-mTOR pathway [35]. The mutation frequency of PIK3CA in CRC ranges from 10% to 30% [36,37]. In our study, the mutation rates of KRAS, BRAF, NRAS, and PIK3CA were 29.8%, 4.3%, 8.5%, and 14.9%, respectively, aligning with previous reports. Notably, KRAS and BRAF were mutually exclusive, whereas PIK3CA mutations frequently co-occurred with other genes, especially KRAS [38,39]. In our cohort, four out of seven PIK3CA mutations co-occurred with KRAS mutation and one with NRAS mutation.
The prognostic role of KRAS and BRAF mutations has been well-established in mCRC, where they guide patient selection for targeted therapies [40]. Patients with KRAS or BRAF mutations are typically excluded from treatment with cetuximab, an anti-EGFR antibody, due to inherent resistance [41]. However, the prognostic impact of these mutations in early-stage CRC has not been conclusively confirmed [42–44]. To derive more reliable conclusions, we performed a meta-analysis that pooled post hoc analyses from phase III trials, which typically offer higher quality evidence compared to retrospective cohort studies. Our analysis revealed that KRAS and BRAF mutations significantly increased the risk of tumor occurrence and death in stage II/III CRC patients. Additionally, we observed a strong interaction between BRAF mutations and MSI status, with a higher HR estimate for DFS in the MSI-adjusted subgroup compared to the non-MSI-adjusted subgroup (1.43 vs 0.98, P = 0.007), and a similar trend for OS (1.59 vs 1.31, P = 0.152). Separate analyses in MSS and MSI-H populations revealed that KRAS and BRAF mutations significantly worsened survival outcomes only in MSS patients (all P values < 0.01), while no significant association was found in the MSI-H population (all P values > 0.05). These results suggest that the negative prognostic impact of KRAS/BRAF mutations is confined to MSS tumors, whereas MSI-H status confers a more favorable prognosis regardless of mutation status. Therefore, assessing both MSI status and KRAS/BRAF mutation status can aid in more accurate prognosis management for stage II/III CRC patients.
Previous studies on the prognostic role of PIK3CA mutation in early stage CRC patients have produced inconsistent results [18,45]. Our meta-analysis suggested a marginally prolonged DFS in patients with PIK3CA mutation (HR = 0.86, 95%CI: 0.75-1.00, P = 0.046). However, this findings were not robust and appeared to be driven by Nowak’s study, where 23.4% of patients used low-dose aspirin [30]. Previous researches suggest that regular aspirin use after CRC diagnosis reduces the recurrence rate in PIK3CA-mutant patients but not in those without PIK3CA mutation [46]. When Nowak’s study was excluded, the association between PIK3CA mutation and DFS became non-significant (P = 0.155). NRAS mutations are relatively rare in CRC, and their prognostic role remains unclear due to limited studies. A previous research in mCRC has associated NRAS mutation with shorter OS [47], and other findings indicate that NRAS mutation is an independent risk factor for poor OS in stage I-II CRC patients [32]. However, phase III trial-based analyses have found no significant association between NRAS mutation and DFS in non-metastatic settings [28,29].
The major limitation of the retrospective analysis is the small sample size. We identified few or no associations between somatic mutations and survival outcomes in this small sample. Yet, we performed a meta-analysis with large sample size to confirm the prognostic impact. Another limitation is the unmatched comparison between the retrospective analysis and meta-analysis according to tumor location and variation in adjuvant therapy. While results of the observational retrospective analysis should be cautiously interpreted, the meta-analysis incorporating post hoc analyses of phase III trials provides a higher level of evidence. Our meta-analysis also has several limitations. First, despite being derived from phase III trials, only a proportion, ranging from 26.2% to 98.5%, of patients in each trial were available for post hoc analyses. Second, the anti-EGRF antibody cetuximab was given in two trials [19,20]. Since KRAS/BRAF mutations confer resistance to cetuximab, the inclusion of cetuximab-treated patients may lead to an overestimation of the prognostic impact. Third, we did not stratify the analysis according to tumor location or stage. Tumor site (proximal or distal, right-sided or left-sided) and stage (II or III) are independent prognostic indicators of CRC and may be confounders for our survival analysis of KRAS/BRAF mutations. For instance, Sinicrope et al. observed that KRAS mutation had negative impact on OS in distal tumors but not in proximal tumors [19]. Additionally, Domingo et al. found that BRAF mutation was associated with shorter DFS in stage III but not in stage II tumors [28]. Finally, our results only highlight the prognostic value of KRAS/BRAF mutations, without addressing their predictive role in therapy outcomes. For example, among BRAF or PIK3CA-mutant patients, there was no survival benefit from adding irinotecan to 5-fluorouracil + leucovorin (5FU/LV) compared to FU/LV alone [17,25].
Conclusions
In conclusion, our study demonstrates that KRAS and BRAF mutations are significantly associated with worse OS and DFS in MSS stage II/III CRC receiving adjuvant therapy after curative surgery. Future large-scale, well-designed studies are needed to explore how these findings can inform adjuvant therapy strategies.
Supporting information
S1 Data. Raw data of the retrospective analysis.
https://doi.org/10.1371/journal.pone.0320783.s002
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S1 Table. Search strategy in literature databases for meta-analysis.
https://doi.org/10.1371/journal.pone.0320783.s004
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S2 Table. Mutations in the KRAS, NRAS, BRAF, and PIK3CA genes in 47 stage II/III CRC patients.
https://doi.org/10.1371/journal.pone.0320783.s005
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S3 Table. Cox regression analysis of OS and DFS in the whole population (n = 47).
https://doi.org/10.1371/journal.pone.0320783.s006
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S4 Table. Cox regression analysis of OS and DFS in MSS population (n = 43).
https://doi.org/10.1371/journal.pone.0320783.s007
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S5 Table. Eligibility assessment for all articles and the exclusion reasons.
https://doi.org/10.1371/journal.pone.0320783.s008
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S6 Table. Quality assessment of included studies using Newcastle-Ottawa Scale for cohort studies.
https://doi.org/10.1371/journal.pone.0320783.s009
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S1 Fig.
Forest plot of meta-analysis of the association between NRAS mutation and survival.
https://doi.org/10.1371/journal.pone.0320783.s010
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S2 Fig.
Forest plot of meta-analysis of the association between PIK3CA mutation and disease-free survival.
https://doi.org/10.1371/journal.pone.0320783.s011
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S3 Fig.
Forest plot of meta-analysis of the association between PIK3CA mutation and overall survival.
https://doi.org/10.1371/journal.pone.0320783.s012
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S4 Fig.
Funnel plot of meta-analysis of the association between KRAS mutation (A) and BRAF mutation (B).
https://doi.org/10.1371/journal.pone.0320783.s013
(PDF)
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