The RAS gene is mutated in approximately what percentage of human cancers, making it the most frequently altered oncogene?

Question

Accepted Answer

A. 30–50%. ## RAS Oncogene Prevalence in Cancer

**Key Point:** RAS mutations are the single most common oncogenic alteration across all human malignancies, found in approximately 30–50% of cancers globally.

### RAS Mutation Frequency by Cancer Type

| Cancer Type | RAS Mutation Frequency | Notes |
| --- | --- | --- |
| Pancreatic adenocarcinoma | 75–90% | Highest frequency |
| Colorectal cancer | 40–50% | Common in adenomas |
| Lung cancer (NSCLC) | 20–30% | Especially adenocarcinoma |
| Melanoma | 15–25% | Varies by subtype |
| Acute myeloid leukemia | 20–30% | FLT3 and NPM1 also common |
| Thyroid cancer | 20–40% | Papillary and follicular types |

**High-Yield:** The 30–50% figure is a testable fact in NEET PG. RAS is the most frequently mutated oncogene, followed by TP53 (most frequently mutated tumor suppressor).

### Why RAS Is So Commonly Mutated

1. **Three isoforms** — KRAS, NRAS, HRAS provide redundancy; mutation of any one can drive cancer
2. **Single amino acid substitution** — Point mutations at codons 12, 13, or 61 cause constitutive GTPase activity
3. **Early event** — RAS mutations often occur early in carcinogenesis, especially in colorectal adenoma-carcinoma sequence
4. **Broad tissue distribution** — RAS is expressed in nearly all cell types

**Mnemonic:** RAS = Remarkably Altered in ~50% of cancers (remember the 30–50% range).

Answer

B. 60–70%

Answer

C. 10–15%

Answer

D. 80–90%

The RAS gene is mutated in approximately what percentage of human cancers, making it the most frequently altered oncogene?

Explanation

RAS Oncogene Prevalence in Cancer

RAS Mutation Frequency by Cancer Type

Why RAS Is So Commonly Mutated

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Cancer Type	RAS Mutation Frequency	Notes
Pancreatic adenocarcinoma	75–90%	Highest frequency
Colorectal cancer	40–50%	Common in adenomas
Lung cancer (NSCLC)	20–30%	Especially adenocarcinoma
Melanoma	15–25%	Varies by subtype
Acute myeloid leukemia	20–30%	FLT3 and NPM1 also common
Thyroid cancer	20–40%	Papillary and follicular types