Neoplasia and Cancer Biology Practice Questions
20 free Neoplasia and Cancer Biology practice questions for the USMLE Step 1. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What is the defining feature that distinguishes a neoplasm from normal hyperplasia or metaplasia?
- A It always regresses once the stimulus is removed
- B Autonomous growth that persists after the stimulus is removed
- C It arises only within epithelial tissues
- D It is invariably malignant from the outset
Correct answer: Autonomous growth that persists after the stimulus is removed
A neoplasm grows autonomously and does not revert when the initiating stimulus is removed, unlike hyperplasia or metaplasia. This independent, clonal growth defines neoplasia.
Which of the following best differentiates benign tumors from malignant neoplasms on gross and microscopic pathology?
- A Benign tumors invade the basement membrane, whereas malignant tumors do not
- B Benign tumors metastasize frequently, while malignant tumors rarely do
- C Benign tumors stay localized and differentiated; malignant invade, metastasize, and show pleomorphism
- D Benign tumors always grow faster than malignant ones
Correct answer: Benign tumors stay localized and differentiated; malignant invade, metastasize, and show pleomorphism
Benign neoplasms generally remain localized, grow expansively without invasion, are well differentiated; malignant neoplasms invade surrounding tissue, may metastasize, and show cellular atypia and pleomorphism.
Which statement about the genetic basis of cancer is most accurate?
- A Oncogene activation requires loss of both alleles
- B Tumor suppressor inactivation usually follows a two-hit mechanism
- C DNA repair genes rarely contribute to carcinogenesis
- D Only inherited germline mutations cause cancer
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.
An activating point mutation in a proto-oncogene converts it into an oncogene. What is the usual effect of this change?
- A Decreased cell proliferation
- B Constitutive activation of growth signaling
- C Enhanced apoptotic cell death
- D Improved DNA-repair capacity
Correct answer: Constitutive activation of growth signaling
Oncogenes — mutated or overexpressed proto-oncogenes — drive constitutive activation of growth signals, promoting uncontrolled proliferation even without external growth factors.
Which hallmark of cancer reflects a tumor’s ability to stimulate formation of blood vessels to support its growth?
- A Evading growth suppressors
- B Inducing angiogenesis
- C Resisting cell death
- D Immune evasion
Correct answer: Inducing angiogenesis
Inducing angiogenesis is a key hallmark of cancer: tumors secrete pro-angiogenic factors to promote new blood vessel formation, ensuring oxygen and nutrient supply for continued growth.
Which of the following features is characteristic of anaplasia in malignant tumors?
- A Uniform cell size and shape
- B Regular, small nuclei with evenly distributed chromatin
- C Prominent nuclear pleomorphism and hyperchromasia
- D Low mitotic activity
Correct answer: Prominent nuclear pleomorphism and hyperchromasia
Anaplastic malignant tumors often show marked pleomorphism (variation in cell and nuclear size/shape), hyperchromatic and irregular nuclei — indicating loss of differentiation.
Which process describes the clonal evolution of neoplastic cells accumulating further mutations over time?
- A Histologic tumor grading
- B Distant metastasis
- C Clonal expansion under genetic instability
- D Tumor angiogenesis
Correct answer: Clonal expansion under genetic instability
As neoplastic cells accumulate mutations (in oncogenes, tumor suppressor genes, DNA repair genes), genetic instability allows clonal evolution and selection of more aggressive subclones — a foundation of cancer progression.
Which of the following cell-intrinsic capabilities is NOT among the classical hallmarks of cancer as per Hanahan & Weinberg’s original model?
- A Sustaining proliferative signaling
- B Evading growth suppressors
- C Inducing angiogenesis
- D Producing anti-immune antibodies
Correct answer: Producing anti-immune antibodies
The original six hallmarks include sustaining proliferation, evading suppressors, resisting death, enabling replicative immortality, inducing angiogenesis, and invasion/metastasis; producing antibodies against immune cells is not one.
The transition from a pre-malignant lesion to invasive cancer typically requires which additional capability acquired by tumor cells?
- A Ability to undergo apoptosis
- B Ability to invade the basement membrane and metastasize
- C Ability to slow its proliferation
- D Ability to fully differentiate
Correct answer: Ability to invade the basement membrane and metastasize
To progress from a premalignant lesion to invasive cancer, cells must gain the ability to invade through the basement membrane, invade surrounding tissue, and potentially metastasize.
Which classification system describes the extent of spread of a malignant tumor including size, lymph node involvement, and metastasis?
- A Grading
- B Staging (TNM)
- C Differentiation score
- D Angiogenesis index
Correct answer: Staging (TNM)
Staging (commonly TNM) assesses the tumor’s size/extent (T), nodal involvement (N), and presence of distant metastasis (M), which helps guide prognosis and therapy.
Which of the following best describes a tumor suppressor gene’s normal function in non-neoplastic cells?
- A Promoting cell cycle progression
- B Stimulating tumor angiogenesis
- C Inhibiting cell division or triggering apoptosis
- D Producing mitogenic growth factors
Correct answer: Inhibiting cell division or triggering apoptosis
Tumor suppressor genes normally act as brakes — they inhibit cell cycle progression, regulate DNA repair or trigger apoptosis — preventing uncontrolled growth. Loss of both alleles removes this control.
Which phenomenon describes neoplastic cells acquiring the ability to divide indefinitely, avoiding normal replicative senescence?
- A Angiogenesis
- B Replicative immortality
- C Differentiation
- D Cell-cell adhesion
Correct answer: Replicative immortality
Replicative immortality is a hallmark of cancer allowing cells to bypass senescence and divide indefinitely, often via maintenance of telomere length or activation of telomerase.
Which structural gene mutation is more likely to be inherited in familial cancer syndromes: an oncogene or a tumor suppressor gene, and why?
- A Oncogene — because gain-of-function always requires inheritance
- B Tumor suppressor gene — one inherited mutant allele predisposes, needing only a 'second hit'
- C Oncogene — because they cause dominant inheritance
- D Neither — cancers are never inherited
Correct answer: Tumor suppressor gene — one inherited mutant allele predisposes, needing only a 'second hit'
In familial cancer syndromes, inheriting one mutated tumor suppressor allele predisposes; a second somatic hit inactivates the remaining allele (two-hit model), leading to neoplasia.
Why are malignant neoplasms often genetically heterogeneous within the same tumor mass?
- A Because they arise from multiple independent cells
- B Because clonal evolution accumulates additional mutations over time
- C Because benign tumors transform to malignant synchronously
- D Because of uniform oncogene expression across all cells
Correct answer: Because clonal evolution accumulates additional mutations over time
Genetic instability in cancer cells leads to accumulation of new mutations over time; clonal evolution produces subpopulations with diverse genetic profiles — accounting for intratumoral heterogeneity.
Which of the following best explains how epigenetic changes (non-mutational) can contribute to cancer development?
- A By causing chromosomal translocations only
- B By permanently activating proto-oncogenes
- C By silencing tumor suppressor genes via promoter methylation
- D By lengthening telomeres to immortalize cells
Correct answer: By silencing tumor suppressor genes via promoter methylation
Epigenetic alterations such as DNA methylation can silence tumor suppressor gene expression without mutation, removing growth control and contributing to oncogenesis.
Which of the following is a major reason that metastasis is characteristic of malignant but not benign tumors?
- A Only malignant tumors can stimulate angiogenesis
- B Benign tumors lack any genetic mutations
- C Metastasis needs invasion, intravasation, circulatory survival, extravasation, and distant growth
- D Benign tumors are too large to enter the bloodstream
Correct answer: Metastasis needs invasion, intravasation, circulatory survival, extravasation, and distant growth
Metastasis is a complex multistep process requiring cellular capabilities like invasion, vascular entry, survival in circulation, exit, and colonization — hallmarks typically present only in malignant cells.
Which term best describes a neoplasm made of cells that resemble the normal tissue of origin and grow slowly, with minimal tendency to invade or metastasize?
- A Poorly differentiated carcinoma
- B Anaplastic sarcoma
- C Benign tumor
- D High-grade malignancy
Correct answer: Benign tumor
Such neoplasms are benign — they are well-differentiated, grow slowly, remain localized, and do not invade or metastasize.
Which of these factors contributes to the genomic instability that facilitates cancer development?
- A Overexpression of DNA repair genes
- B Activation of caretaker genes
- C Loss-of-function mutations in DNA-repair genes
- D Increased cell adhesion molecules
Correct answer: Loss-of-function mutations in DNA-repair genes
Caretaker genes maintain genomic integrity by DNA repair; when they are inactivated, mutations accumulate unchecked, increasing the risk of oncogene activation or tumor suppressor loss — fostering neoplasia.
In histopathological grading of tumors, what does a high-grade tumor generally imply compared to a low-grade tumor?
- A More differentiated cells and a better prognosis
- B Slower growth with no local invasion
- C Poor differentiation, high mitotic rate, aggressive behavior
- D Benign behavior with no risk of metastasis
Correct answer: Poor differentiation, high mitotic rate, aggressive behavior
High-grade tumors show poor differentiation (anaplasia), high mitotic rate, and aggressive behavior, correlating with worse prognosis compared to low-grade, well-differentiated tumors.
Which of the following is most likely to be a paraneoplastic syndrome rather than a direct effect of tumor mass or metastasis?
- A Compression of adjacent structures by a lung tumor
- B Hypercalcemia from PTHrP secreted by a squamous cell carcinoma
- C Bone pain from skeletal metastases
- D Biliary obstruction by a pancreatic head tumor
Correct answer: Hypercalcemia from PTHrP secreted by a squamous cell carcinoma
Paraneoplastic syndromes are mediated by substances secreted by tumor cells (e.g., PTHrP causing hypercalcemia), not by direct mass effect or metastasis.