Diagnosis and Management of Bone Metastasis in Stage IV Breast Cancer
Presentation
A 55-year-old postmenopausal female, who has been married for 25 years and has three children, is diagnosed with stage IV ER/PR-positive, HER2-negative breast cancer. She begins treatment with palbociclib and letrozole. After a few months, she experiences right hip/groin pain. At first, the pain is mild and intermittent, and she believes it is muscular in nature as she has been recently walking with her friends. However, it becomes more intense and frequent over the ensuing 3 months despite icing the area, modifying her activity, and taking ibuprofen. Now, her pain is constant even at rest and increases with weight-bearing activities. She brings this to the attention of her advanced practitioner, who immediately orders pelvic and femur x-rays.
Workup and Diagnosis
The x-rays reveal a mixed osteoblastic/osteolytic bone lesion of the right proximal femur in the intertrochanteric area. The bone lesion takes up about one- to two-thirds width of the bone. The patient is referred to orthopedic oncology for evaluation and meets with a physician assistant (PA).
The PA performs a physical exam focusing on the right hip and notes some tenderness with maximum external rotation of the right hip, as well as mild pain with palpation of the right hip greater trochanter. The patient has a slight antalgic gait (i.e., a limp that develops in response to pain) to the right but does not need ambulatory assistive devices and has full range of motion of the hip. The rest of the right hip and groin is nontender to palpate, neurovascularly intact right lower extremity and calf is supple to palpate, and there are no overlying skin changes to the right hip or groin.
The PA assesses the x-rays, along with the patient’s report of mechanical pain (pain worse with ambulation), using Mirels’ classification system. This system predicts the risk of pathologic fracture among bones affected by metastases by examining location, pain, type of bone lesion, and size and assigning a score from 1 to 3 for each category. A total score of 9 or higher requires surgery, a score of 8 should be considered for surgery, and a score of 7 or less can be managed with radiation and follow-up with no need for surgery.1-3 This patient has a score of 10.
Next, the PA orders a total-body bone scan to see if there are any other areas of concern that require further evaluation. The results reveal increased uptake only in the right hip region.
The diagnosis of metastatic bone disease to the right hip significant for an impending pathologic fracture is made.
Treatment and Management
First, the patient undergoes surgical stabilization using an intramedullary nail to prevent a pathologic fracture of the right hip. A sample of the bone lesion is taken at the time of surgery and sent to pathology. After the patient recovers from surgery, the PA refers her to radiation oncology for external beam radiation to the right hip.
The PA discusses using bone-targeted agents, including a bisphosphonate or denosumab, to help mitigate further bone destruction from the metastatic bone disease. The PA also educates the patient on calcium and vitamin D supplementation, maintaining a healthy diet rich in dairy products, not smoking and limiting alcohol use, incorporating gentle weight-bearing activities, and the importance of continuing breast cancer treatment with her oncologist.
The patient follows up with her orthopedic oncology PA 3 weeks after surgery to ensure complete healing and no signs of infection, receive femur x-rays, and to get approval to start radiation therapy. The patient returns at 3 months post-op and reports her pain has greatly subsided and that she has been able to resume the activities she enjoys. This patient is followed by the orthopedic oncology team yearly thereafter to monitor the right femur and internal fixation via physical exam and x-rays.
References
- Mirels H. Metastatic disease in long bones: A proposed scoring system for diagnosing impending pathologic fractures. 1989. Clin Orthop Relat Res. 2003;(415 Suppl):S4-13.
- Damron TA, Morgan H, Prakash D, et al. Critical evaluation of Mirels' rating system for impending pathologic fractures. Clin Orthop Relat Res. 2003;(415 Suppl):S201-7.
- Jawad MU, Scully SP. In brief: classifications in brief: Mirels' classification: metastatic disease in long bones and impending pathologic fracture. Clin Orthop Relat Res. 2010;468(10):2825-7.
