Orthopedic Teaching Cases 2023, Jan, 18 | 12:00 am

Orthopedic Oncology cases side effects of bisphosphonates

An 80-year-old female presents to your office with newly diagnosed lung cancer. She has multiple skeletal metastases. She complains of pain in the thoracic and

lumbar spine as well as in the left tibia; she has several lytic lesions in these areas. She also complains of abdominal pain and some weakness.

What is the most likely metabolic abnormality that explains these symptoms?

  1. Anemia

  2. Hyponatremia

  3. Hyperkalemia

  4. Hypercalcemia

 

Discussion

The correct answer is (D). Hypercalcemia is present in 10% to 15% of cases of metastatic bone disease. It is especially common with lung and breast cancer. Symptoms include polyuria, polydipsia, anorexia, weakness, fatigue, and nausea/vomiting. Depression, irritability, coma, pruritus, and vision abnormalities are late symptoms.

She asks about bisphosphonate therapy. What is the mechanism of action of these agents?

  1. They induce osteoblastic activity

  2. They increase calcium and vitamin D uptake

  3. They inhibit osteoclastic activity

  4. They increase the thickness of cortical bone

 

Discussion

The correct answer is (C). Bisphosphonates inhibit osteoclastic activity by preventing the formation of microtubules at the cell’s ruffled border, inducing apoptosis and preventing bone resorption. These agents are used in almost all cases of metastatic bone disease and can significantly decrease the risk of skeletal events.

What are the major concerns with utilization of bisphosphonates?

  1. Electrolyte abnormalities and cerebral edema

  2. Osteonecrosis of the jaw and atypical femoral stress fractures

  3. Increased risk of lymphoma and osteonecrosis of the femoral head

  4. Stress fractures in the lower extremity and cerebral edema

 

Discussion

The correct answer is (B). There is a small incidence of osteonecrosis as well as

atypical proximal femur stress fractures described with long-term utilization of bisphosphonate therapy. No significant electrolyte abnormalities, risk of hematologic malignancy, osteonecrosis, or change in intracranial pressure has been described as a complication.

 

Objectives: Did you learn...?

 

Indications and side effects of bisphosphonates?

 

Metabolic abnormalities associated with metastatic bone disease?