Bone metastases are a common complication of certain solid tumors, and breast and prostate cancers are the tumor categories that most often have bone involvement. Bone is the most common site of metastasis in prostate cancer, with approximately 90% of patients with advanced prostate cancer having bone metastases. Moreover, once a tumor metastasizes to bone, it is currently almost incurable.
The dangers of bone metastases
Most patients with progressive prostate cancer will eventually develop bone metastases, most often in the spine, pelvis, and ribs.
The development of bone metastases from prostate cancer leads to disturbances in bone metabolism and increased osteoblast and osteoclast activity, resulting in sclerotic or osteogenic lesions on imaging. Pathological osteoclast activity is often accompanied by bone-related events, disease progression, and even death.
The disease burden of prostate cancer bone metastases is high, as patients often present with severe bone pain and even associated complications such as pathologic fractures, spinal instability, and spinal cord compression.
Treatment of bone metastases
The current treatment is mainly palliative. The goals of treatment for prostate cancer bone metastases are primarily to relieve pain, prevent and reduce the occurrence of bone-related events (pathological fractures, spinal cord compression, etc.), and improve quality of life.
For bone metastases from prostate cancer, the main treatments available include:
- Endocrine therapy;
- chemotherapy for hormone-resistant prostate cancer;
- molecular targeting and immunotherapy, which is a new treatment approach now available;
- Biphosphonate therapy, which can be used as basic therapy in combination with chemotherapy, radiotherapy, surgery, and endocrine therapy to effectively treat bone destruction, relieve bone pain, and prevent and delay bone-related events;
- radiotherapy;
- Surgical treatment, i.e., resection of bone metastases followed by reconstruction.
Bone metastases are divided into four main categories according to different characteristics:
- Class I is evaluated as having a good prognosis for primary prostate cancer with a single bone metastasis, and the time between the discovery of the primary site and the appearance of the bone metastasis is more than 3 years;
- Class II presents with pathologic fractures of the major long bones (humerus, ulna, radius, femur, tibia, and fibula are long bones);
- Class III is an imaging or clinical sign of an impending pathological fracture of the major long bones or around the acetabulum;
- Class IV are multiple osteogenic metastases, osteolytic or mixed metastases on non-weight-bearing bones (e.g., fibula, ribs, sternum, clavicle, etc.), osteolytic lesions on major long bones without a tentative risk of fracture, and lesions located on the iliac wing, anterior pelvis, or scapula (excluding patients in Class I).
Different treatment options for different categories of patients:
- All patients with prostate cancer bone metastases in categories I, II, and III should undergo surgery followed by other adjuvant therapy;
- Class IV patients should be treated with a conservative approach, i.e., a combination of endocrine therapy, chemotherapy, bisphosphonate therapy, targeted and immunotherapy, radiotherapy, and cancer pain treatment with personalized treatment. The patient’s response to treatment and control of pain should be carefully evaluated after treatment. If pain persists for up to 2 months after the end of conservative treatment or if imaging shows continued progression of the lesion, the patient needs to be re-evaluated for surgical treatment.
Regular follow-up during treatment
After starting treatment for prostate cancer bone metastases, follow-up visits are recommended every 3 months, including physical examination, blood PSA, routine blood, liver and kidney function, and alkaline phosphatase.
Bone scans, ultrasounds, and chest CTs are recommended for those who develop elevated PSA and other symptoms during treatment. However, when the patient is hormone-non-dependent, follow-up should be closer and an individualized follow-up plan is recommended.
Anti-pain treatment
In addition to these approaches, pain management has an irreplaceable role in bone metastases from prostate cancer. NSAIDs (ibuprofen, anti-inflammatory suppositories, Keflex injection) and opioid analgesics (dulcolax, prednisolone, morphine, etc.) can be used depending on the mild to moderate severity of pain, respectively.
The treatment of cancer pain is still individualized, with individualized treatment for different stages of disease and different levels of pain, making sure to reduce the patient’s pain to a minimum.
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