Q (sonnet-5.5): What are the most frequent EGFR mutation variants in lung adenocarcinoma and what percentage are known hotspot mutations?

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

▶ list_studies
{
 "search": "lung adenocarcinoma",
 "limit": 50
}

◀ 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":[{"cancer_study_identifier":"msk_met_2021","name":"MSK MetTropism (MSK, Cell 2021)","type_of_cancer_id":"mixed","sample_count":25775,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=msk_met_2021"},{"cancer_study_identifier":"luad_mskcc_2023_met_organotropism","name":"Lung Adenocarcinoma Met Organotropism (MSK, Cancer Cell 2023)","type_of_cancer_id":"luad","sample_count":2653,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=luad_mskcc_2023_met_organotropism"},{"cancer_study_identifier":"lung_msk_2017","name":"Non-Small Cell Cancer (MSK, Cancer Discov 2017)","type_of_cancer_id":"luad","sample_count":915,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=lung_msk_2017"},{"cancer_study_identifier":"luad_mskcc_2020","name":"Lung Adenocarcinoma (MSK, J Thorac Oncol 2020)","type_of_cancer_id":"luad","sample_count":604,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=luad_mskcc_2020"},{"cancer_study_identifier":"luad_tcga","name":"Lung Adenocarcinoma (TCGA, Firehose Legacy)","type_of_cancer_id":"luad","sample_count":586,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=luad_tcga"},{"cancer_study_identifier":"luad_tcga_gdc","name":"Lung Adenocarcinoma (TCGA GDC, 2025)","type_of_cancer_id":"luad","sample_count":571,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=luad_tcga_gdc"},{"cancer_study_identifier":"luad_tcga_pan_can_atlas_2018","name":"Lung Adenocarcinoma (TCGA, PanCancer Atlas)","type_of_cancer_id":"luad","sample_count":566,"has_guide":true,"url":"https://www.cbioportal.org/study/summary?id=luad_tcga_pan_can_atlas_2018"},{"cancer_study_identifier":"luad_msk_npjpo_2021","name":"Lung Adenocarcinoma (MSK, NPJ Precision Oncology 2021)","type_of_cancer_id":"luad","sample_count":426,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=luad_msk_npjpo_2021"},{"cancer_study_identifier":"luad_oncosg_2020","name":"Lung Adenocarcinoma (OncoSG, Nat Genet 2020)","type_of_cancer_id":"luad","sample_count":305,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=luad_oncosg_2020"},{"cancer_study_identifier":"lung_msk_mind_2020","name":"Lung Adenocarcinoma (MSK Mind,Nature Cancer 2022)","type_of_cancer_id":"lung","sample_count":247,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=lung_msk_mind_2020"},{"cancer_study_identifier":"luad_cptac_gdc","name":"Lung Adenocarcinoma (CPTAC GDC, 2025)","type_of_cancer_id":"luad","sample_count":241,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=luad_cptac_gdc"},{"cancer_study_identifier":"luad_tcga_pub","name":"Lung Adenocarcinoma (TCGA, Nature 2014)","type_of_cancer_id":"luad","sample_count":230,"has_guide":false,"url":"https://www.cbioportal.org/study/summary?id=luad_tcga_pub"},{"cancer_study_identifier":"luad_mskimpact_2021","name":"Lung Adenocarcinoma (MSK, 2021)","type_of_cancer_id":"luad","sample_count":186,"has_guide":false, … (1174 more chars)

▶ clickhouse_run_select_query
{
 "query": "SELECT * FROM gene_mutation_variants_in_study(study='luad_tcga_pan_can_atlas_2018', gene='EGFR') ORDER BY altered_samples DESC LIMIT 25"
}

▶ clickhouse_list_table_columns
{
 "table": "genomic_event_derived"
}

◀ result
{"rows":[{"mutation_variant":"L858R","mutation_type":"Missense_Mutation","altered_samples":23,"profiled_samples":566,"frequency_pct":4.1,"total_mutation_events":23},{"mutation_variant":"E746_A750del","mutation_type":"In_Frame_Del","altered_samples":16,"profiled_samples":566,"frequency_pct":2.8,"total_mutation_events":16},{"mutation_variant":"L861Q","mutation_type":"Missense_Mutation","altered_samples":3,"profiled_samples":566,"frequency_pct":0.5,"total_mutation_events":3},{"mutation_variant":"E709_T710delinsD","mutation_type":"In_Frame_Del","altered_samples":3,"profiled_samples":566,"frequency_pct":0.5,"total_mutation_events":3},{"mutation_variant":"G719A","mutation_type":"Missense_Mutation","altered_samples":2,"profiled_samples":566,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"L747_A750delinsP","mutation_type":"In_Frame_Del","altered_samples":2,"profiled_samples":566,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"T790M","mutation_type":"Missense_Mutation","altered_samples":2,"profiled_samples":566,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"S768I","mutation_type":"Missense_Mutation","altered_samples":2,"profiled_samples":566,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"L62R","mutation_type":"Missense_Mutation","altered_samples":2,"profiled_samples":566,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"L747_T751del","mutation_type":"In_Frame_Del","altered_samples":2,"profiled_samples":566,"frequency_pct":0.4,"total_mutation_events":2},{"mutation_variant":"I759N","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"A767_V769dup","mutation_type":"In_Frame_Ins","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"L747_E749del","mutation_type":"In_Frame_Del","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"L387M","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"X210_splice","mutation_type":"Splice_Region","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"D770_N771insGL","mutation_type":"In_Frame_Ins","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"L907M","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"L833F","mutation_type":"Missense_Mutation","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"D1083Efs*11","mutation_type":"Frame_Shift_Del","altered_samples":1,"profiled_samples":566,"frequency_pct":0.2,"total_mutation_events":1},{"mutation_variant":"Q432H","mut … (898 more chars)

◀ result
{"columns":[{"name":"sample_unique_id","type":"String"},{"name":"hugo_gene_symbol","type":"String","comment":"HUGO gene symbol (e.g., TP53, KRAS, BRAF). Use for gene-specific queries."},{"name":"entrez_gene_id","type":"Int32"},{"name":"gene_panel_stable_id","type":"LowCardinality(String)"},{"name":"cancer_study_identifier","type":"LowCardinality(String)"},{"name":"genetic_profile_stable_id","type":"LowCardinality(String)"},{"name":"variant_type","type":"LowCardinality(String)","comment":"Type of genomic event: \"mutation\" for SNVs/indels, \"cna\" for copy number alterations, \"structural_variant\" for SVs. Always filter by this."},{"name":"mutation_variant","type":"String","comment":"Protein change notation (e.g., p.V600E, p.R175H). Use for specific variant queries. \"NA\" for non-mutation events."},{"name":"mutation_type","type":"LowCardinality(String)"},{"name":"mutation_status","type":"LowCardinality(String)","comment":"For mutations: Somatic, Germline, UNKNOWN, or UNCALLED. Filter mutation_status != \"UNCALLED\" to exclude uncertain calls. Include all other statuses."},{"name":"driver_filter","type":"LowCardinality(String)"},{"name":"driver_filter_annotation","type":"String"},{"name":"driver_tiers_filter","type":"LowCardinality(String)"},{"name":"driver_tiers_filter_annotation","type":"String"},{"name":"cna_alteration","type":"Nullable(Int8)","comment":"Copy number alteration: only 2 = amplification (AMP) and -2 = deep deletion (HOMDEL) are stored. Shallow deletion (-1), diploid (0) and gain (1) are not in this table; query genetic_alteration_derived WHERE profile_type = 'gistic' (alteration_value is a String, e.g. '-1'). NULL for non-CNA events."},{"name":"cna_cytoband","type":"String"},{"name":"sv_event_info","type":"String"},{"name":"patient_unique_id","type":"String"},{"name":"off_panel","type":"Bool","comment":"Boolean: 1 = mutation outside gene panel coverage (off-panel), 0 = within panel (on-panel). Filter off_panel = 0 for reliable frequency calculations."}]}

▶ clickhouse_run_select_query
{
 "query": "SELECT uniqExact(sample_unique_id) AS mutated_samples, uniqExactIf(sample_unique_id, mutation_variant IN ('L858R','E746_A750del','L747_A750delinsP','L747_T751del','L747_E749del','T790M','G719A','L861Q','S768I','L833V','L833F')) AS classic_samples, uniqExactIf(sample_unique_id, mutation_variant IN ('L858R','E746_A750del','L747_A750delinsP','L747_T751del','L747_E749del','T751_I759delinsN')) AS l858r_exon19 FROM genomic_event_derived WHERE cancer_study_identifier='luad_tcga_pan_can_atlas_2018' AND hugo_gene_symbol='EGFR' AND variant_type='mutation' AND mutation_status!='UNCALLED' AND off_panel=0"
}

▶ resolve_and_route
{
 "studyIds": [
  "luad_tcga_pan_can_atlas_2018"
 ]
}

◀ result
{"rows":[{"mutated_samples":70,"classic_samples":51,"l858r_exon19":45}]}

◀ result
{"success":true,"message":"Found 1 study. Use the metadata to call the appropriate navigation tool(s).","data":{"totalCount":1,"studiesWithMetadata":[{"studyId":"luad_tcga_pan_can_atlas_2018","name":"Lung Adenocarcinoma (TCGA, PanCancer Atlas)","sampleCount":566,"studyViewUrl":"https://www.cbioportal.org/study?id=luad_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":["luad_tcga_pan_can_atlas_2018_gistic","luad_tcga_pan_can_atlas_2018_log2CNA","luad_tcga_pan_can_atlas_2018_mutations","luad_tcga_pan_can_atlas_2018_rna_seq_v2_mrna","luad_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_Zscores","luad_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_all_sample_Zscores","luad_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_all_sample_ref_normal_Zscores","luad_tcga_pan_can_atlas_2018_rppa","luad_tcga_pan_can_atlas_2018_rppa_Zscores","luad_tcga_pan_can_atlas_2018_structural_variants"],"genericAssayProfiles":["luad_tcga_pan_can_atlas_2018_armlevel_cna","luad_tcga_pan_can_atlas_2018_genetic_ancestry","luad_tcga_pan_can_atlas_2018_methylation_hm27_hm450_merge","luad_tcga_pan_can_atlas_2018_methylation_hm450"],"heatmapProfileIds":["luad_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_Zscores","luad_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_all_sample_Zscores","luad_tcga_pan_can_atlas_2018_rna_seq_v2_mrna_median_all_sample_ref_normal_Zscores","luad_tcga_pan_can_atlas_2018_rppa_Zscores"],"availableComparisonTabs":["overlap","clinical","survival","alterations","mutations","mrna","protein","generic_assay_armlevel_cna","generic_assay_genetic_ancestry","generic_assay_methylation"]}}]}}

▶ navigate_to_results_view
{
 "studyIds": [
  "luad_tcga_pan_can_atlas_2018"
 ],
 "genes": [
  "EGFR: MUT"
 ],
 "tab": "mutations"
}

◀ result
{"success":true,"message":"Navigating to https://www.cbioportal.org/results/mutations?cancer_study_list=luad_tcga_pan_can_atlas_2018&gene_list=EGFR%3A+MUT&case_set_id=luad_tcga_pan_can_atlas_2018_all","url":"https://www.cbioportal.org/results/mutations?cancer_study_list=luad_tcga_pan_can_atlas_2018&gene_list=EGFR%3A+MUT&case_set_id=luad_tcga_pan_can_atlas_2018_all","data":{"studyIds":["luad_tcga_pan_can_atlas_2018"],"studies":[{"studyId":"luad_tcga_pan_can_atlas_2018","name":"Lung Adenocarcinoma (TCGA, PanCancer Atlas)","sampleCount":566}],"genes":["EGFR"],"caseSetId":"luad_tcga_pan_can_atlas_2018_all","pageDescription":"Detailed mutation table with lollipop plot showing mutation positions, types, and frequencies for queried genes."}}

═ answer (success)
**Cohort:** TCGA PanCancer Atlas lung adenocarcinoma (`luad_tcga_pan_can_atlas_2018`). I counted samples, and 566 were profiled for EGFR. I chose this study because you didn't name one. Many other lung adenocarcinoma studies are available (MSK, OncoSG, CPTAC and others), and I can rerun this on any of them.

**EGFR mutations:** 70 of 566 samples (12.4%) carry at least one EGFR mutation.

**Most frequent variants**

| Variant | Type | Samples | % of 566 profiled |
|---|---|---|---|
| L858R | Missense | 23 | 4.1% |
| E746_A750del | In-frame deletion | 16 | 2.8% |
| L861Q | Missense | 3 | 0.5% |
| E709_T710delinsD | In-frame deletion | 3 | 0.5% |
| G719A | Missense | 2 | 0.4% |
| L747_A750delinsP | In-frame deletion | 2 | 0.4% |
| T790M | Missense | 2 | 0.4% |
| S768I | Missense | 2 | 0.4% |
| L62R | Missense | 2 | 0.4% |
| L747_T751del | In-frame deletion | 2 | 0.4% |

Each of the remaining variants appears in a single sample. They include an exon 20 insertion (D770_N771insGL) and several other missense, truncating and splice variants.

**Percentage that are known hotspots:** I can't give an exact figure from the data. cBioPortal works out hotspot status when you view a study and doesn't store it. The data I could query has no hotspot annotation for this study.

As a rough stand-in, I counted the well-characterized activating variants in the kinase domain from general knowledge, not from cBioPortal annotation. These were L858R, the exon 19 in-frame deletions, G719A, L861Q, S768I, L833V/F and T790M.

- **L858R plus exon 19 in-frame deletions:** 45 of 70 mutated samples (about 64%).
- **All the variants listed above:** 51 of 70 mutated samples (about 73%).

Treat these as approximate. To get portal-annotated hotspots, open the Mutations tab below, where hotspot flags are shown for each variant.

[View EGFR mutations in TCGA PanCancer Atlas LUAD (Mutations tab)](https://www.cbioportal.org/results/mutations?cancer_study_list=luad_tcga_pan_can_atlas_2018&gene_list=EGFR%3A+MUT&case_set_id=luad_tcga_pan_can_atlas_2018_all)