Is Forteo (teriparatide) contraindicated in a patient with a history of breast cancer?

Treatment of Severe Osteoporosis in a Patient with Breast Cancer History and CKD Stage 3

Bisphosphonates are the recommended first-line treatment for this 83-year-old female with severe osteoporosis (T-score -3.0) and a history of breast cancer, as teriparatide (Forteo) is contraindicated in patients with a history of malignancy prone to metastasize to bone. 1

Contraindication of Teriparatide (Forteo)

Teriparatide is contraindicated in this patient for several important reasons:

1. History of breast cancer: Guidelines specifically state that teriparatide should be avoided in patients with a history of malignancy prone to metastasize to bone, which includes breast cancer 1. The National Comprehensive Cancer Network (NCCN) task force report on bone health in cancer care explicitly states that "teriparatide is best avoided in patients with a history of malignancy prone to metastasize to bone." 1

2. Theoretical mechanism of risk: Teriparatide works by increasing bone turnover, which may potentially promote propagation of microscopic bone metastases through liberation of bone-derived growth factors and cytokines 1. This mechanism could theoretically reactivate dormant cancer cells.

3. Preclinical concerns: The FDA black box warning for teriparatide stems from rat studies showing increased risk of osteosarcoma 2. While human surveillance has not shown a significant increase in osteosarcoma risk in the general population, the risk-benefit calculation changes in patients with prior malignancy.

4. Radiation history: The patient received radiation therapy for breast cancer, which is an additional risk factor for osteosarcoma and another contraindication for teriparatide use 2, 3.

Recommended Treatment Algorithm

Given her severe osteoporosis, history of breast cancer, and CKD stage 3 with GFR of 30, the treatment algorithm should be:

1. First-line therapy: Denosumab (Prolia) 60mg subcutaneously every 6 months 4

   • Preferred over oral bisphosphonates due to her renal impairment
   • Not renally cleared and can be used safely in CKD stage 3
   • Highly effective at reducing vertebral, non-vertebral, and hip fractures

2. Alternative option: IV zoledronic acid with dose adjustment for renal function

   • If used, dose should be reduced and infusion time extended due to GFR of 30

3. Adjunctive therapy:

   • Calcium supplementation: 1,200 mg daily (monitor carefully due to CKD)
   • Vitamin D supplementation: 800-1,000 IU daily
   • Regular weight-bearing and resistance exercises as tolerated

Important Monitoring Considerations

• Monitor renal function regularly, especially if bisphosphonates are used
• Baseline dental examination before starting therapy to assess risk of osteonecrosis of the jaw
• Calcium levels should be monitored, especially with her renal impairment
• Follow-up BMD testing in 1-2 years to assess treatment response

Pitfalls to Avoid

1. Using teriparatide despite contraindications: Even though teriparatide is a potent anabolic agent that could address her severe osteoporosis, the risk of potentially activating dormant breast cancer cells outweighs the benefits 1.

2. Ignoring renal function: Standard doses of bisphosphonates could worsen her renal function with a GFR of 30.

3. Inadequate calcium/vitamin D supplementation: Essential for any osteoporosis treatment to be effective.

4. Overlooking dental health: Patients on antiresorptive therapy should have dental evaluation before starting treatment to minimize risk of osteonecrosis of the jaw.

This treatment approach prioritizes both fracture risk reduction and cancer safety considerations, addressing her severe osteoporosis while respecting the contraindication of teriparatide in her clinical scenario.