What are the common side effects of radiation therapy and how are they managed?

Common Side Effects of Radiation Therapy and Their Management

Radiation therapy causes a range of acute and late side effects that significantly impact patients' quality of life, with management strategies varying based on the affected organ system and severity of symptoms.

Radiation Dermatitis

Radiation dermatitis is one of the most common side effects, experienced by the majority of patients undergoing radiotherapy for cancer, particularly head and neck cancers 1.

Incidence and Severity

• Mild to moderate dermatitis (grades 1-2) occurs in most patients
• Severe reactions (grade 3-4) occur in 20-25% of patients 1
• Severity depends on:
  • Total radiation dose
  • Dose per fraction
  • Overall treatment time
  • Beam type and energy
  • Surface area of skin exposed 1

Management Based on Grade

• Grade 1: Follow treatment recommendations for skin care; gentle washing with mild, unscented soap is acceptable 1, 2
• Grade 2 and above: Apply topical steroids and emollient creams 2
• For patients receiving EGFR inhibitors with radiation: management should be based on dermatitis grade, with specific protocols for when acne-like rash and dermatitis coexist 1

Gastrointestinal Side Effects

Radiation Esophagitis

• Management:
  • Dietary modifications
  • Proton pump inhibitors
  • Promotility agents
  • Viscous lidocaine for pain relief 2

Radiation-Induced Nausea/Vomiting

• Treatment: 5-hydroxytryptamine3 receptor antagonists (5-HT3 antagonists) combined with steroids 2

Gastrointestinal Toxicity in Pelvic Radiation

• Recent studies suggest gut microbiome plays a role in determining gastrointestinal side effects 1
• Routine follow-up visits should assess for GI symptoms during and after treatment 1

Neurological and Cognitive Effects

Neurocognitive Function (NCF) Deficits

• Occurs in up to 90% of patients with brain metastases 1
• Can be caused by:
  • Direct tumor effects
  • Treatment side effects (surgery, radiation, chemotherapy, immunotherapy) 1

Management of Cognitive Symptoms

• Pharmacological approaches:
  • Donepezil (acetylcholinesterase inhibitor) - slight benefits for recognition memory 1
  • Memantine - protective effects when administered during radiation 1
  • Methylphenidate and modafinil - mixed results for attention and fatigue 1
• Non-pharmacological approaches:
  • Cognitive rehabilitation with compensatory strategies and "cognitive exercise" paradigms 1

Radiation Necrosis

• Occurs in 0-30% of patients undergoing radiosurgery 1
• Management algorithm:
  1. Initial observation if asymptomatic
  2. Glucocorticoids for symptomatic patients
  3. If steroids fail or cause unacceptable side effects:
     • Neurosurgical resection
     • Laser interstitial thermal therapy (LITT)
     • Bevacizumab (supported by randomized studies) 1

Genitourinary Side Effects

Radiation Cystitis

• Symptomatic treatments:
  • Anticholinergic agents
  • Phenazopyridine 2

Sexual Dysfunction

• For erectile dysfunction: Phosphodiesterase type 5 inhibitors 2
• For vaginal stenosis: Vaginal dilators 2
  • Long-term use indicated to reduce grade 2 late vaginal stenosis 1
  • Poor compliance may limit improvement 1

Late Effects Requiring Monitoring

Cardiovascular Disease

• Well-established adverse effect of radiation therapy
• No consensus recommendations for cardiovascular screening 2

Endocrine Effects

• Hypothyroidism
• Hyperparathyroidism 3

Secondary Cancers

• Long-term risk requiring surveillance, particularly in pediatric patients 4

Prevention Strategies

Modern Radiotherapy Techniques

• Intensity-modulated radiotherapy (IMRT)
• Volumetric modulated arc therapy (VMAT)
• Image-guided radiotherapy (IGRT)
• These techniques reduce occurrence and severity of toxicity by improving precision 1, 4

Patient Education and Preparation

• Patients should be informed about potential side effects before treatment
• Specific preparation may be required (e.g., bladder filling, dietary recommendations) 1
• For sexual dysfunction, patients should be fully informed about potential issues and approaches to reduce discomfort 1

Follow-up Recommendations

• Regular assessment of toxicities during treatment using specific grading scales (RTOG, CTCAE) 1
• Patient-reported outcome measures to recognize and prevent acute toxicity 1
• Long-term follow-up to monitor for late effects 1
• Multidisciplinary approach for management of complex late toxicities 1

Key Considerations for Clinicians

1. Early recognition and intervention can prevent progression of side effects
2. Treatment planning should follow guidelines and dose constraints for organs at risk
3. Patient and disease characteristics should inform preventive strategies
4. Differential diagnosis is important as symptoms may be due to exacerbation of existing conditions rather than radiation effects 4
5. Quality of life considerations are particularly important in pediatric patients who may live many years with long-term effects 4

By understanding the mechanisms of radiation toxicity and implementing appropriate preventive and management strategies, clinicians can improve symptom control and quality of life for patients undergoing radiation therapy.