Q (sonnet): Which KRAS mutations are most common in colorectal cancer?

▶ read_guide
{
 "uri": "cbioportal://mutation-frequency-guide"
}

▶ search_oncotree
{
 "search_term": "colorectal"
}

◀ result
# Mutation Frequency Analysis Guide

## IMPORTANT: Reporting Mutation Frequencies
- **ALWAYS report frequencies as percentages**, not raw counts: `frequency = (altered_samples / total_profiled_samples) × 100`
- For quick frequency lookups, **prefer the TCGA Pan-Cancer Atlas study first**, then offer to expand to other studies
- When reporting across multiple studies, show **ranges** (e.g., "TP53 is mutated in 30–60% of samples") rather than a single average
- **NEVER** sum mutation events across studies to compute an aggregate frequency — this can exceed 100% due to double-counting
- Warn users that samples may overlap across cohorts (e.g., MSK studies may share patients)
- **Choose and state the counting unit**: use patient-level frequencies for prevalence/rate questions unless the user explicitly asks for samples; use sample-level frequencies when the user asks about samples.
- **For "across cancer types" questions**, jump to the [Cross-Cancer-Type Mutation Frequency](#cross-cancer-type-mutation-frequency) section below — there is one correct recipe and several common wrong ones.

## Counting Unit: Samples vs Patients

Before answering any mutation count or frequency question, decide whether the unit is samples or patients and state that choice in the answer.

| User wording | Counting unit |
|--------------|---------------|
| "prevalence", "rate", "fraction of patients", "patients with", "how common is" | Patient-level: `COUNT(DISTINCT patient_unique_id)` |
| "samples", "specimens", "biopsies", sample-level cohort composition | Sample-level: `COUNT(DISTINCT sample_unique_id)` |
| Ambiguous | Ask, or default to patient-level for prevalence/rate language and say so |

### Cross-study sample-count caveat

When an answer touches more than one study and reports a sample count, prepend a one-line caveat:

> Sample IDs are unique within cBioPortal study prefixes, not guaranteed biological-sample identifiers across studies; overlapping cohorts can count the same patient/sample more than once.

Prefer one of these safer approaches:

- Use a shipped `cancer_study_query_preferences` cohort such as `pan_cancer_tcga` or `all_studies_non_redundant`.
- Restrict to one named study.
- Aggregate by `patient_unique_id` when the biological question is patient prevalence.

## STOP rule: a frequency above 100% means your query is wrong

If your query returns a frequency over 100%, **do not try to debug or explain the data inconsistency to the user**. The cause is always one of these query bugs:

- Summing mutation events instead of `COUNT(DISTINCT sample_unique_id)` for the numerator
- Using a study-wide sample count as the denominator instead of the gene-specific profiled count
- Cross-study aggregation where the same biological sample appears under multiple `sample_unique_id` values (e.g., MSK-IMPACT and MSK-CHORD share patients)
- **Joining the profiled CTE through `gene_panel` / `gene_panel_list` without a WES branch.** `gene_panel_id = 'WES'` is *not* a row in … (36467 more chars)

◀ result
{"result":[{"code":"COADREAD","name":"Colorectal Adenocarcinoma","score":60,"mainType":"Colorectal Cancer","tissue":"Bowel","hierarchy":"BOWEL > COADREAD"},{"code":"CAIS","name":"Colon Adenocarcinoma In Situ","score":45,"mainType":"Colorectal Cancer","tissue":"Bowel","hierarchy":"BOWEL > COADREAD > CAIS"},{"code":"CMC","name":"Medullary Carcinoma of the Colon","score":45,"mainType":"Colorectal Cancer","tissue":"Bowel","hierarchy":"BOWEL > CMC"},{"code":"COAD","name":"Colon Adenocarcinoma","score":45,"mainType":"Colorectal Cancer","tissue":"Bowel","hierarchy":"BOWEL > COADREAD > COAD"},{"code":"MACR","name":"Mucinous Adenocarcinoma of the Colon and Rectum","score":45,"mainType":"Colorectal Cancer","tissue":"Bowel","hierarchy":"BOWEL > COADREAD > MACR"},{"code":"READ","name":"Rectal Adenocarcinoma","score":45,"mainType":"Colorectal Cancer","tissue":"Bowel","hierarchy":"BOWEL > COADREAD > READ"},{"code":"SRCCR","name":"Signet Ring Cell Adenocarcinoma of the Colon and Rectum","score":45,"mainType":"Colorectal Cancer","tissue":"Bowel","hierarchy":"BOWEL > COADREAD > SRCCR"}]}

▶ list_studies
{
 "search": "Colorectal Adenocarcinoma TCGA PanCancer Atlas"
}

◀ result
{"result":[{"cancer_study_identifier":"coadread_tcga_pan_can_atlas_2018","name":"Colorectal Adenocarcinoma (TCGA, PanCancer Atlas)","type_of_cancer_id":"coadread","sample_count":594,"has_guide":true,"url":"https://www.cbioportal.org/study/summary?id=coadread_tcga_pan_can_atlas_2018"}]}

▶ clickhouse_run_select_query
{
 "query": "SELECT * FROM gene_mutation_variants_in_study(study = 'coadread_tcga_pan_can_atlas_2018', gene = 'KRAS') ORDER BY altered_samples DESC LIMIT 20"
}

◀ result
{"rows":[{"mutation_variant":"G12D","mutation_type":"Missense_Mutation","altered_samples":58,"profiled_samples":534,"frequency_pct":10.9,"total_mutation_events":58},{"mutation_variant":"G12V","mutation_type":"Missense_Mutation","altered_samples":49,"profiled_samples":534,"frequency_pct":9.2,"total_mutation_events":49},{"mutation_variant":"G13D","mutation_type":"Missense_Mutation","altered_samples":37,"profiled_samples":534,"frequency_pct":6.9,"total_mutation_events":37},{"mutation_variant":"A146T","mutation_type":"Missense_Mutation","altered_samples":16,"profiled_samples":534,"frequency_pct":3,"total_mutation_events":16},{"mutation_variant":"G12C","mutation_type":"Missense_Mutation","altered_samples":15,"profiled_samples":534,"frequency_pct":2.8,"total_mutation_events":15},{"mutation_variant":"G12A","mutation_type":"Missense_Mutation","altered_samples":10,"profiled_samples":534,"frequency_pct":1.9,"total_mutation_events":10},{"mutation_variant":"G12S","mutation_type":"Missense_Mutation","altered_samples":8,"profiled_samples":534,"frequency_pct":1.5,"total_mutation_events":8},{"mutation_variant":"K117N","mutation_type":"Missense_Mutation","altered_samples":4,"profiled_samples":534,"frequency_pct":0.7,"total_mutation_events":4},{"mutation_variant":"Q61H","mutation_type":"Missense_Mutation","altered_samples":4,"profiled_samples":534,"frequency_pct":0.7,"total_mutation_events":4},{"mutation_variant":"Q61K","mutation_type":"Missense_Mutation","altered_samples":3,"profiled_samples":534,"frequency_pct":0.6,"total_mutation_events":3},{"mutation_variant":"Q61R","mutation_type":"Missense_Mutation","altered_samples":2,"profiled_samples":534,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"G12R","mutation_type":"Missense_Mutation","altered_samples":2,"profiled_samples":534,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"G13C","mutation_type":"Missense_Mutation","altered_samples":2,"profiled_samples":534,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"E98*","mutation_type":"Nonsense_Mutation","altered_samples":1,"profiled_samples":534,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"Q61L","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":534,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"A155D","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":534,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"A146V","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":534,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"Q61P","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":534,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"Y71C","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":534,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"Q22K","mutation_type":"Missense_Mutation","alter … (85 more chars)

▶ resolve_and_route
{
 "studyIds": [
  "coadread_tcga_pan_can_atlas_2018"
 ]
}

◀ result
{"success":true,"message":"Found 1 study. Use the metadata to call the appropriate navigation tool(s).","data":{"totalCount":1,"studiesWithMetadata":[{"studyId":"coadread_tcga_pan_can_atlas_2018","name":"Colorectal Adenocarcinoma (TCGA, PanCancer Atlas)","sampleCount":594,"studyViewUrl":"https://www.cbioportal.org/study?id=coadread_tcga_pan_can_atlas_2018","metadata":{"clinicalAttributeIds":["AGE","AJCC_PATHOLOGIC_TUMOR_STAGE","AJCC_STAGING_EDITION","ANEUPLOIDY_SCORE","BUFFA_HYPOXIA_SCORE","CANCER_TYPE","CANCER_TYPE_ACRONYM","CANCER_TYPE_DETAILED","DAYS_LAST_FOLLOWUP","DAYS_TO_BIRTH","DAYS_TO_INITIAL_PATHOLOGIC_DIAGNOSIS","DFS_MONTHS","DFS_STATUS","DSS_MONTHS","DSS_STATUS","ETHNICITY","FORM_COMPLETION_DATE","FRACTION_GENOME_ALTERED","GENETIC_ANCESTRY_LABEL","GRADE","HISTORY_NEOADJUVANT_TRTYN","ICD_10","ICD_O_3_HISTOLOGY","ICD_O_3_SITE","INFORMED_CONSENT_VERIFIED","IN_PANCANPATHWAYS_FREEZE","MSI_SCORE_MANTIS","MSI_SENSOR_SCORE","MUTATION_COUNT","NEW_TUMOR_EVENT_AFTER_INITIAL_TREATMENT","ONCOTREE_CODE","OS_MONTHS","OS_STATUS","OTHER_PATIENT_ID","PATH_M_STAGE","PATH_N_STAGE","PATH_T_STAGE","PERSON_NEOPLASM_CANCER_STATUS","PFS_MONTHS","PFS_STATUS","PRIMARY_LYMPH_NODE_PRESENTATION_ASSESSMENT","PRIOR_DX","RACE","RADIATION_THERAPY","RAGNUM_HYPOXIA_SCORE","SAMPLE_COUNT","SAMPLE_TYPE","SEX","SOMATIC_STATUS","SUBTYPE","TBL_SCORE","TISSUE_PROSPECTIVE_COLLECTION_INDICATOR","TISSUE_RETROSPECTIVE_COLLECTION_INDICATOR","TISSUE_SOURCE_SITE","TISSUE_SOURCE_SITE_CODE","TMB_NONSYNONYMOUS","TUMOR_TISSUE_SITE","TUMOR_TYPE","WEIGHT","WINTER_HYPOXIA_SCORE"],"molecularProfileIds":["coadread_tcga_pan_can_atlas_2018_gistic","coadread_tcga_pan_can_atlas_2018_log2CNA","coadread_tcga_pan_can_atlas_2018_mutations","coadread_tcga_pan_can_atlas_2018_protein_quantification","coadread_tcga_pan_can_atlas_2018_protein_quantification_zscores","coadread_tcga_pan_can_atlas_2018_rna_seq_v2_mrna","coadread_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_Zscores","coadread_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_all_sample_Zscores","coadread_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_all_sample_ref_normal_Zscores","coadread_tcga_pan_can_atlas_2018_rppa","coadread_tcga_pan_can_atlas_2018_rppa_Zscores","coadread_tcga_pan_can_atlas_2018_structural_variants"],"genericAssayProfiles":["coadread_tcga_pan_can_atlas_2018_armlevel_cna","coadread_tcga_pan_can_atlas_2018_genetic_ancestry","coadread_tcga_pan_can_atlas_2018_methylation_hm27_hm450_merge","coadread_tcga_pan_can_atlas_2018_methylation_hm450"],"heatmapProfileIds":["coadread_tcga_pan_can_atlas_2018_protein_quantification_zscores","coadread_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_Zscores","coadread_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_all_sample_Zscores","coadread_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_all_sample_ref_normal_Zscores","coadread_tcga_pan_can_atlas_2018_rppa_Zscores"],"availableComparisonTabs":["overlap","clinical","survival","alterations","mutations","mrna","protein","generic_assay_armlevel_c … (70 more chars)

▶ navigate_to_results_view
{
 "studyIds": [
  "coadread_tcga_pan_can_atlas_2018"
 ],
 "genes": [
  "KRAS"
 ],
 "tab": "mutations"
}

◀ result
{"success":true,"message":"Navigating to https://www.cbioportal.org/results/mutations?cancer_study_list=coadread_tcga_pan_can_atlas_2018&gene_list=KRAS&case_set_id=coadread_tcga_pan_can_atlas_2018_all","url":"https://www.cbioportal.org/results/mutations?cancer_study_list=coadread_tcga_pan_can_atlas_2018&gene_list=KRAS&case_set_id=coadread_tcga_pan_can_atlas_2018_all","data":{"studyIds":["coadread_tcga_pan_can_atlas_2018"],"studies":[{"studyId":"coadread_tcga_pan_can_atlas_2018","name":"Colorectal Adenocarcinoma (TCGA, PanCancer Atlas)","sampleCount":594}],"genes":["KRAS"],"caseSetId":"coadread_tcga_pan_can_atlas_2018_all","pageDescription":"Detailed mutation table with lollipop plot showing mutation positions, types, and frequencies for queried genes."}}

═ answer (success)
## KRAS mutations in colorectal cancer

Using the [Colorectal Adenocarcinoma (TCGA, PanCancer Atlas)](https://www.cbioportal.org/study/summary?id=coadread_tcga_pan_can_atlas_2018) cohort — 594 samples, 534 profiled for mutations (sample-level counts) — the most common specific KRAS protein changes are:

| Variant | Samples altered | Frequency (of 534 profiled) |
|---|---|---|
| **G12D** | 58 | 10.9% |
| **G12V** | 49 | 9.2% |
| **G13D** | 37 | 6.9% |
| A146T | 16 | 3.0% |
| G12C | 15 | 2.8% |
| G12A | 10 | 1.9% |
| G12S | 8 | 1.5% |
| K117N / Q61H | 4 each | 0.7% |
| Q61K | 3 | 0.6% |
| Q61R / G12R / G13C | 2 each | 0.4% |

All are missense mutations. Codon 12 (G12D, G12V, G12C, G12A, G12S) and codon 13 (G13D) substitutions dominate, together accounting for roughly 33% of samples, with G12D and G12V the clear leaders — consistent with the classic KRAS hotspots described in colorectal cancer. Rarer hits occur at A146 (exon 4) and Q61 (exon 3). Any patient could carry more than one variant, but each row above counts samples with that specific change at least once.

For the full lollipop plot with exon positions and mutation-type breakdown, see the [KRAS Mutations tab for this cohort](https://www.cbioportal.org/results/mutations?cancer_study_list=coadread_tcga_pan_can_atlas_2018&gene_list=KRAS&case_set_id=coadread_tcga_pan_can_atlas_2018_all).