Can adjuvant radiation therapy be omitted after breast conserving surgery in elderly patients with early stage breast cancer?

Omission of Adjuvant Radiation Therapy After Breast Conserving Surgery in Elderly Early Stage Breast Cancer

Adjuvant radiation therapy can safely be omitted after breast conserving surgery in women ≥70 years with ER-positive, clinically node-negative T1 breast cancers who will receive adjuvant endocrine therapy. 1

Patient Selection Criteria for Omitting Radiation Therapy

Radiation therapy may be safely omitted in elderly patients who meet ALL of the following criteria:

• Age ≥70 years
• Early-stage breast cancer (T1 tumor, ≤2 cm)
• Clinically node-negative disease
• Estrogen receptor-positive tumor
• Clear surgical margins after breast conserving surgery
• Commitment to complete 5 years of adjuvant endocrine therapy (tamoxifen or aromatase inhibitor)

Evidence Supporting Omission of Radiation Therapy

The NCCN Guidelines provide strong evidence (category 1) supporting the omission of radiation therapy in carefully selected elderly patients 1. Multiple clinical trials have demonstrated this approach is safe:

• A landmark study of women ≥70 years with clinical stage I, node-negative, ER-positive breast cancer with negative margins randomized to lumpectomy with whole breast radiation therapy (WBRT) versus lumpectomy alone with adjuvant tamoxifen showed:

  • At 12.6 years median follow-up, the 10-year local recurrence rates were 2% with RT versus 10% without RT
  • No differences in overall survival, disease-free survival, or need for mastectomy between groups 1

• The PRIME II study of women ≥65 years with node-negative breast cancers <3 cm showed:

  • At 5 years follow-up, ipsilateral breast tumor recurrences were 1.3% with RT versus 4.1% without RT
  • No differences in overall survival, regional recurrence, distant metastases, or contralateral breast cancers 1

Risks and Benefits Analysis

Benefits of Omitting Radiation:

• Avoids radiation-related side effects
• Reduces treatment burden (daily treatments over several weeks)
• No impact on overall survival or distant metastasis risk
• Particularly beneficial for patients with limited mobility or transportation issues

Risks of Omitting Radiation:

• Modest increase in local recurrence risk (approximately 8% at 10 years)
• Local recurrence may require additional surgery

Important Considerations and Caveats

1. Patient Adherence to Endocrine Therapy: The safety of omitting radiation therapy depends on patient adherence to the prescribed 5-year course of endocrine therapy. Poor adherence may increase recurrence risk.

2. Tumor Biology: Consider additional tumor characteristics beyond size and receptor status. Higher-grade tumors or those with lymphovascular invasion may warrant radiation despite meeting age criteria.

3. Patient Preference: Some patients may prefer the small absolute reduction in local recurrence risk provided by radiation despite the inconvenience of treatment.

4. Life Expectancy: Consider overall life expectancy when making this decision. Patients with limited life expectancy due to comorbidities may derive less benefit from radiation therapy.

5. Follow-up Requirements: Ensure patients have access to appropriate follow-up care for monitoring of potential recurrence.

Algorithm for Decision-Making

1. Confirm patient meets ALL eligibility criteria:

   • Age ≥70 years
   • T1 (≤2 cm) tumor
   • Clinically node-negative
   • ER-positive
   • Clear surgical margins
   • Plan for 5 years of endocrine therapy

2. Assess patient's ability to tolerate and adhere to endocrine therapy

3. Discuss absolute risks and benefits with patient:

   • 8% absolute reduction in 10-year local recurrence with radiation
   • No difference in overall survival or distant metastasis
   • Radiation side effects versus convenience of omitting radiation

4. Make shared decision based on patient values and preferences

For patients who do not meet these strict criteria (younger age, larger tumors, node-positive disease, or ER-negative tumors), standard whole breast radiation therapy remains the recommended approach after breast conserving surgery 1.