I. Overview
Bone is the most common site of metastasis for malignant tumors other than lung and liver. About 70% to 80% of cancer patients will eventually develop bone metastasis, and its incidence is about 35 to 40 times that of primary malignant bone tumors. Bone metastases tend to occur in middle and old age, with a male to female ratio of about 3:1. Most cases clinically manifest as multiple bone destruction. The spine, pelvis and long bone epiphysis are the most common sites of bone metastases. Common clinical manifestations mainly include: pain (50%-90%); pathological fracture (5%-40%); hypercalcemia (10%-20%); spinal instability and spinal cord and nerve root compression symptoms (<10%); and bone marrow suppression (<10%).
II. Classification of tissue origin
Bone metastasis of breast cancer
Bone metastasis of prostate cancer
Bone metastasis of lung cancer
Bone metastasis of thyroid cancer
Bone metastasis of kidney cancer
Esophageal Cancer
Gastric Cancer
Rectal Cancer
Bladder Cancer
Cervical Cancer
Ovarian Cancer
Liver Cancer
Malignant melanoma
Myeloma
Bone metastases staging and scoring system
1.Spinal metastases staging and scoring system
Tomita staging
Tomita score
Score
Prognostic factors
Primary tumor
Visceral metastasis
Bone metastasis
1
Slow growth
No metastasis
Single or isolated
2
Moderate growth
Inhibitable treatment
Multiple
3
Rapid growth
Untreatable
Bunger’s revised Tokuhshi scoring system
Item
Score
General status (Karnofsky score)
Poor (10%-40%)
0
Moderate(50%-70%)
1
Good (80%-100%)
2
Number of extra-spinal bone metastases
>3
0
1-2
1
0
2
Number of spinal involvement
>3
0
2
1
1
2
Significant organ metastases
Unresectable
0
Resectable
1
No metastasis
2
Tumor primary organ
Lung, stomach, unknown origin
0
Kidney, liver, uterus
1
Breast, rectum, thyroid, prostate, lymphoma
2
Spinal cord damage
Total paraplegia
0
Incomplete paraplegia
1
Normal
2
2.Long bone metastases of the extremities score
Mirels score for pathological fracture of long bone metastases
Item
Mirels score
1 point
2 points
3 points
Part
Upper Extremity
Lower extremity
Around the rotor
Pain
Mild
Moderate
Severe
Nature of lesion
Osteogenic
Mixed
Osteolytic
Lesion size
<1/3 of circumference
Circumference 1/3-2/3
>2/3 circumference
3.Pelvic metastases subdivision
Enneking pelvic tumor subdivision
Type
Tumor site
Type I
Iliac bone
Type II
Peri-acetabular
Type III
Pubic bone, sciatic bone
Type IV
Iliac lesions involving the sacrum
Harrington’s staging of periacetabular metastases
Typology
Tumor site
Type I
Periacetabular lesion
Type II
Bone destruction of the medial acetabular wall
Type III
Bone destruction at the peri-acetabular rim
Type IV
Isolated peri-acetabular metastases
IV. Treatment process of bone metastases
1.Bone metastasis diagnosis process
2.Treatment process of bone metastases
2.1 Treatment process of spinal metastases
2.2 Surgical treatment of long bone metastases in the extremities
Indications for surgery of long bone metastases
Patients in good general condition with expected survival greater than 12 weeks
Preoperative evaluation determines that the patient would benefit from surgical treatment (postoperative patient can start activities early or facilitate care)
Isolated metastases with complete resection of the primary site or curable
Pathologic fracture that reduces the patient’s quality of life
High risk of pathologic fracture while performing daily activities
Mirels score greater than 9
50% of the bone cortex is destroyed on radiographs
Lesion diameter greater than 2.5 cm
Disruption of the femoral tuberosity
Upper extremity lesions are less likely to fracture than lower extremities, and prophylactic fixation should be indicated more strictly
Failure of radiotherapy or persistent pain that cannot be relieved
Principles of surgery for long bone metastases
1.The purpose of surgical operation is to prevent pathological fractures from occurring or to restore the continuity of pathological fractures.
2. Try to minimize the damage to the soft tissues around the bone.
3.Select the most effective fixation method so that the patient can recover the limb function in the shortest time after surgery.
4.For less severe cortical destruction, closed intramedullary pin technique is available. Those with extensive destruction should be incised to remove the tumor, filled with bone cement and applied with internal fixation.
5.Tumor should be resected thoroughly.
6.For those with rich blood flow, arterial embolization is feasible before surgery.
7. Minimize surgical trauma and surgery-related mortality.
8.The bone and soft tissue conditions around the lesion are suitable for surgery, and strong fixation can be obtained.
2.3 Surgical treatment of pelvic metastases
Harrington divided the periacetabular metastases into 4 types according to the site of tumor involvement in the acetabulum, and took the corresponding surgical measures according to the site of tumor involvement. Type I: the acetabular articular surface is diseased, while the medial wall, parietal wall and marginal cortex of the acetabulum are intact, treatment can be done by traditional cemented total hip replacement; Type II: the medial wall of the acetabulum is bone destroyed, the rest of the parietal wall and marginal cortex of the acetabulum are not affected, the use of ordinary acetabulum will lead to early medial displacement of the prosthesis and cement, the acetabulum with winged mesh cups can be used to direct the stress to the acetabular rim, and then cemented total Hip joint replacement;
Type III: there is bone destruction in the inner wall, parietal wall and edge of the acetabulum, several Stiffen pins can be placed in the pelvic defect during surgery to facilitate stress transfer from the acetabulum to the spine.
Type IV: isolated periacetabular metastases, complete resection of the tumor and pelvic reconstruction can be performed.
Surgical treatment of metastatic cancer in pelvic region II
The patient has heavy symptoms and the effect of braking, analgesic medication and anti-tumor therapy is not good
The patient’s pain is not relieved after radiotherapy or the function of the affected limb is not restored satisfactorily.
Pathological fractures in or near the ipsilateral femur need to be treated simultaneously.
Surgical treatment of metastatic cancer in pelvic region I and IV
The posterior medial part of the ilium (which is responsible for stress transmission between the acetabulum and the sacrum) is involved by the tumor.
Without reconstruction after tumor removal, patients are likely to suffer from complications such as unequal length of both lower limbs and separation of the pubic symphysis after surgery.
When the lesion involves the adjacent sacral wing and the sacral bone defect is obvious after tumor resection, the arch root internal fixation system can be applied to connect the lumbar spine with the residual bone above the acetabulum and strengthen it with bone cement.
When the soft tissue involvement is obvious and the neurovascular bundle is severely involved, hemipelvic amputation can be chosen.
In sacroiliac joint metastases, those with light destruction are asymptomatic and do not need to do internal fixation treatment; those with severe destruction have displacement, instability and pain, and should be treated with internal fixation.
Surgical treatment of metastatic cancer in pelvic region III
Isolated metastatic lesion of pubic situs. Since the mechanical conduction mechanism between femur and sacrum still exists, most operators believe that bone reconstruction is not necessary after simple zone III resection and basically does not affect the function of lower limbs after surgery.
Patients with an expected survival of more than 6 months, isolated bone metastases or only one bone metastasis in an important area, and good general condition should be considered for surgical treatment. Patients with extensive and multiple metastases as well as poor general condition and expected survival time of less than 3 months are not recommended to take surgical treatment.
Patients with tumors involving the pubic bone, the sciatic bone and the iliac bone who have significant effect on radiotherapy, are expected to survive for a long time and have obvious symptoms can be treated surgically to improve their functions.
V. Principles and indications of preoperative biopsy
If the patient’s history of malignant tumor is clear and multiple bone damages (long bones, vertebrae, pelvis) are found in the whole body at the same time, preoperative biopsy is not a necessary operation.
If the patient has a clear history of malignant tumor and single bone destruction, biopsy should be performed to clarify the diagnosis before planning the surgery.
Patients with no history of tumor but suspected metastatic cancer in bone must undergo preoperative biopsy to exclude lymphoma, myeloma and sarcoma, and if metastatic cancer is diagnosed, the primary tumor should be searched under the guidance of pathological results.
Indications for radiotherapy
Patients are unable to tolerate surgery and have an expected survival of less than 12 months.
Patients with low risk of current pathological fracture.
Spinal lesions without significant spinal instability and neurological symptoms.
Patients whose pelvic tumors do not involve the acetabulum and have no significant functional impairment.
Radiation therapy sensitive tumors.
Prevention of recurrence after local excision of metastatic foci.