Radiation Therapy Principles and Side Effects Flashcards

A male patient completes prostate radiation therapy and reports erectile dysfunction 18 months later. The MOST likely etiology of this late effect is:

Answer: Radiation-induced fibrosis of the neurovascular bundles and penile vasculature

Late radiation-induced erectile dysfunction is primarily caused by damage to the neurovascular bundles lateral to the prostate and radiation arteritis affecting penile blood flow.

Which grading system is most commonly used in clinical trials to standardize reporting of radiation therapy adverse effects?

Answer: NCI Common Terminology Criteria for Adverse Events (CTCAE)

The NCI CTCAE is the standard system used in oncology clinical trials to classify and grade adverse events including radiation-related toxicities.

A patient with esophageal cancer develops odynophagia and dysphagia during the third week of concurrent chemoradiation. CT shows mucosal thickening of the esophagus without perforation. What is the most appropriate management?

Answer: Provide symptomatic management with viscous lidocaine, analgesics, and nutritional support

Acute radiation esophagitis is expected during chemoradiation for esophageal cancer and is managed symptomatically with analgesics, mucosal coating agents, and nutritional optimization while continuing treatment.

In brachytherapy for cervical cancer, the point 'Point A' is used to prescribe dose. Where is Point A located?

Answer: 2 cm superior to the cervical os and 2 cm lateral to the uterine canal

Point A is defined as 2 cm superior to the cervical os (or vaginal fornix) and 2 cm lateral to the uterine canal, representing the region of the parametria and paracervical triangle.

Which of the following radiation sensitizers works by mimicking oxygen and thereby enhancing radiation-induced DNA damage in hypoxic tumor cells?

Answer: Nimorazole

Nimorazole is a nitroimidazole hypoxic cell sensitizer that mimics oxygen, fixing radiation-induced free radical damage in hypoxic tumor cells that would otherwise be repaired.

A patient who received mantle field radiation for Hodgkin lymphoma 20 years ago is now diagnosed with coronary artery disease at age 42. This represents which category of late radiation effect?

Answer: Accelerated atherosclerosis as a radiation late effect

Mediastinal radiation accelerates atherosclerosis in the coronary arteries, leading to premature coronary artery disease in Hodgkin lymphoma survivors, a well-recognized late cardiovascular toxicity.

When managing a patient with radiation recall dermatitis triggered by docetaxel administered after prior radiation, the MOST appropriate initial intervention is:

Answer: Withholding the offending chemotherapy agent and treating with topical corticosteroids

Radiation recall dermatitis is managed by discontinuing the triggering agent and using topical or systemic corticosteroids; re-challenge decisions are made after resolution based on clinical necessity.