Q (haiku): How many total studies contain mutation data in the cBioPortal database?

▶ clickhouse_run_select_query
{
 "query": "
SELECT COUNT(DISTINCT cancer_study_id) as total_studies_with_mutations
FROM cancer_study
WHERE mutation_sample_count > 0
"
}

◀ result
{"rows":[{"total_studies_with_mutations":542}]}

═ answer (success)
**542 studies** in the cBioPortal database contain mutation data.

This count includes all studies where at least one sample has been profiled for mutations (`mutation_sample_count > 0`). These studies span diverse cancer types, data sources (TCGA, MSK, GEO, TARGET, etc.), and time periods.