CH 25 & 26

T/F: Neutron therapy showed clear clinical benefits for most tumor types.

False

neutron therapy only helped a few cancers and caused too much toxicity

T/F: The main limitation of neutron therapy is unacceptable late normal tissue toxicity.

True

T/F: BNCT relies on boron-containing drugs that selectively accumulate in tumor cells.

True

T/F: Thermal neutrons used in BNCT have excellent tissue penetration.

False

thermal neutrons only penetrate shallow tissue and cannot reach deep tumors well

T/F: Protons have an RBE similar to megavoltage x-rays.

True

T/F: The Bragg peak represents the point where charged particles deposit maximum energy at a predictable depth.

True

T/F: Carbon ion therapy provides both a sharp Bragg peak and high LET at the tumor site.

True

T/F: Carbon ions have greater lateral scattering than protons, leading to less precise edges.

False

carbon ions scatter less, giving sharper edges than protons

T/F: HIF-1α is rapidly degraded under normoxic conditions due to VHL-mediated ubiquitination.

True

T/F: Mutations that inactivate VHL cause decreased HIF activity.

False

without VHL, HIF is not degraded, so HIF activity actually increases

T/F: The Unfolded Protein Response (UPR) helps tumor cells survive chronic hypoxia.

True

T/F: Tirapazamine selectively kills well-oxygenated tumor cells.

False

TPZ is activated only in hypoxic cells

T/F: Nicotinamide reduces acute/perfusion-limited hypoxia.

True

T/F: Carbogen breathing can worsen hypoxia due to vasoconstriction.

False

carbogen prevents vasoconstriction by adding CO₂, improving oxygen delivery

T/F: ARCON therapy combines accelerated radiotherapy with carbogen and nicotinamide.

True

Which tumors showed benefit from neutron therapy?
A. Pancreatic
B. Salivary gland
C. Breast
D. Glioblastoma

Salivary gland

BNCT works by producing which particle inside tumor cells?
A. Gamma rays
B. Positrons
C. Alpha particles
D. Beta particles

Alpha particles

What is the major challenge of BNCT?
A. Neutrons cause no biological effect
B. Boron drugs lack sufficient tumor selectivity
C. Neutrons penetrate too deeply
D. Boron is radioactive

Boron drugs lack sufficient tumor selectivity

The Bragg peak is characteristic of which modality?
A. Neutrons
B. MRI-guided radiotherapy
C. Proton therapy
D. Ultrasound therapy

Proton therapy

Why are carbon ions more biologically potent than protons?
A. Higher LET near the Bragg peak
B. Longer range in tissue
C. Higher RBE in the entrance region
D. Lower interaction cross section

Higher LET near the Bragg peak

HIF-1α degradation under normal oxygen requires which protein?
A. TP53
B. VHL
C. mTOR
D. APC

VHL

PHD enzymes require which molecule as a substrate to hydroxylate HIF-α?
A. CO₂
B. O₂
C. Glucose
D. NADPH

O2

Loss of VHL is strongly associated with which cancer?
A. Melanoma
B. Thyroid cancer
C. Clear cell renal carcinoma
D. Hodgkin lymphoma

Clear cell renal carcinoma

Which pathway is part of the Unfolded Protein Response?
A. PHD/VHL
B. IRE1 → XBP1
C. Ras → RAF
D. VEGF → VEGFR

IRE1 → XBP1

PERK activation leads to:
A. Increased protein synthesis
B. Decreased protein translation
C. Increased angiogenesis
D. Increased glycolysis

Decreased protein translation

Hypoxic cell radiosensitizers work by:
A. Killing only hypoxic cells
B. Mimicking effects of oxygen during radiation
C. Blocking glycolysis
D. Increasing blood flow

Mimicking effects of oxygen during radiation

Which drug is a classic hypoxic radiosensitizer?
A. Tirapazamine
B. Misonidazole
C. Carboplatin
D. Doxorubicin

Misonidazole

Tirapazamine becomes cytotoxic under:
A. High oxygen
B. Hypoxic conditions
C. Acidic pH only
D. High dose radiation only

Hypoxic conditions

Carbogen breathing improves oxygenation mainly by:
A. Reducing tumor metabolism
B. Preventing oxygen-induced vasoconstriction
C. Increasing mitochondrial respiration
D. Inducing tumor apoptosis

Preventing oxygen-induced vasoconstriction

ARCON therapy is designed to address:
A. Only chronic hypoxia
B. Only acute hypoxia
C. Both acute and chronic hypoxia
D. Hypoxia unrelated to tumors

Both acute and chronic hypoxia