What is the recommended follow-up care for a patient 12 years after diagnosis of HER2-positive (Human Epidermal growth factor Receptor 2-positive) invasive ductal carcinoma, who has completed 10 years of therapy?

Follow-Up Care After Completing 10 Years of Therapy for HER2-Positive Invasive Ductal Carcinoma

For a patient 12 years after diagnosis who has completed 10 years of adjuvant therapy with no evidence of disease, active treatment should be discontinued and the patient should transition to standard surveillance without ongoing HER2-targeted therapy. 1

Rationale for Treatment Discontinuation

The most recent expert guidelines (2025) specifically address this clinical scenario and provide clear direction:

• Treatment continuation beyond 10 years is not supported by evidence. The standard duration of adjuvant trastuzumab-based therapy is 52 weeks (1 year), not indefinite treatment. 2, 3

• For patients with prolonged complete response (no evidence of disease for ≥5 years), treatment discontinuation can be considered on a case-by-case basis. Retrospective data show excellent outcomes with 5-year overall survival of 90.5% and 10-year overall survival of 87% in patients who achieved complete response after at least 5 years of HER2-targeted therapy. 1

• Your patient has exceeded both the standard 1-year adjuvant treatment duration and the 5-year threshold for exceptional responders. At 12 years post-diagnosis with 10 years of completed therapy, continuing treatment offers no additional benefit and only exposes the patient to unnecessary toxicity risk. 1

Important Context: This Appears to Be Early-Stage Disease

The question describes a patient who completed "10 years of therapy" for HER2-positive invasive ductal carcinoma. This clinical scenario requires clarification:

• Standard adjuvant therapy for early-stage HER2-positive breast cancer is 1 year (52 weeks) of trastuzumab-based treatment, not 10 years. 2, 3

• If this patient truly received 10 years of continuous HER2-targeted therapy, this would be highly unusual and suggests either:

  • Metastatic disease being treated with indefinite therapy (though the question states "completed" therapy, suggesting curative intent)
  • Extended adjuvant therapy far beyond guideline recommendations
  • Possible confusion about treatment duration

Surveillance Recommendations Going Forward

Standard breast cancer surveillance should continue indefinitely:

• Clinical examination every 3-6 months for the first 3 years after completing treatment, then every 6-12 months for years 4-5, then annually. 2

• Annual mammography (and breast MRI if indicated based on breast density or genetic risk factors). 2

• No routine laboratory testing or imaging beyond mammography is recommended in asymptomatic patients without evidence of recurrence. 2

• Cardiac monitoring is no longer required since HER2-targeted therapy has been discontinued and the patient is >10 years from anthracycline exposure (if received). 2

Management if Recurrence Occurs

The timing of recurrence relative to completion of adjuvant therapy determines treatment approach:

• If recurrence occurred ≤12 months after completing trastuzumab-based adjuvant treatment: Follow second-line HER2-targeted therapy recommendations (trastuzumab emtansine/T-DM1 or trastuzumab deruxtecan). 1, 2

• If recurrence occurs >12 months after completing adjuvant treatment (which applies to your patient): Restart first-line HER2-targeted therapy with trastuzumab, pertuzumab, and taxane-based chemotherapy. 1, 2

• At 12 years post-diagnosis, any recurrence would be considered late recurrence (>12 months from treatment completion) and should be treated as first-line metastatic disease. 1, 2

Critical Pitfall to Avoid

Do not continue HER2-targeted therapy indefinitely in the adjuvant setting. The evidence supports 1 year of adjuvant trastuzumab, and even extending to 2 years showed no additional benefit (HR 0.99,95% CI 0.87-1.13, p=0.90 for disease-free survival). 3 Continuing beyond the evidence-based duration exposes patients to unnecessary cardiac toxicity, infusion reactions, and healthcare costs without survival benefit.

Special Consideration: Hormone Receptor Status

If the patient's tumor was hormone receptor-positive:

• Endocrine therapy should continue for at least 5-10 years total from diagnosis (this may still be ongoing if the patient is within 10 years of diagnosis). 2

• For premenopausal patients at diagnosis who received ovarian suppression, continuation depends on menopausal status and risk factors. 2

• Endocrine therapy continuation is independent of HER2-targeted therapy completion. 2