Neoplasia and Cancer Biology · USMLE Step 1

Which statement about the genetic basis of cancer is most accurate?

  1. Oncogene activation requires loss of both alleles
  2. Tumor suppressor inactivation usually follows a two-hit mechanism
  3. DNA repair genes rarely contribute to carcinogenesis
  4. Only inherited germline mutations cause cancer
Show answer and explanation

Correct answer: Tumor suppressor inactivation usually follows a two-hit mechanism

Tumor suppressor genes typically follow the two-hit hypothesis — both alleles must be inactivated (mutated or silenced) to remove their growth-inhibitory effect.

Difficulty: Medium Question 3 of 20

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