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What is Bone Metastasis?
The cancer burden in India has risen considerably over the last decade due to increased awareness and diagnosis. The availability of affordable world-class healthcare for treating cancer has allowed a longer survival.
This improvement in survival rates has also increased the incidence and identification of cancer spreading to other parts of the body, most commonly to the lungs, bones and visceral organs. This bony involvement is called ‘Bone Metastasis’, and it impacts survival while also deteriorating the quality of life for that duration.
Cancers of breasts, prostate, thyroid, kidney, lungs and intestines in decreasing order are known to frequently spread to bones.
What are the symptoms of Bone Metastasis?
An individual with bone metastasis secondary to known cancer or sometimes, an unknown primary cancer, can have symptoms present themselves with pain, pathological fractures (trivial trauma) or compression of the spinal cord leading to weakness and disability as well as loss of function. A detailed personal and treatment history is elicited to identify primary cancer followed by targeted investigations.
The most common sites of bone involvement in decreasing order are the spine, pelvis-hips, long bones such as femur, humerus, tibia, radius and rarely clavicle and scapula.
What are the tests done to identify Bone Metastasis?
In the event there is a suspicion of bone metastasis (primary cancer is not known or identified), the individual undergoes blood tests (serum level of calcium, phosphorous and alkaline phosphatase, cancer markers such as CA 125, CEA, CA 19.9, PSA etc.) followed by imaging.
In imaging, a plain x-ray of the involved bone is performed followed by either CT or MRI scan depending on the nature of the presentation. A targeted scan such as CT of chest-abdomen-pelvis is also done when the suspicion is towards visceral primary cancer or identified risk factors.
An image-guided needle biopsy of the involved bone is performed by a Musculoskeletal Oncosurgeon or by the Interventional Radiologist (CT guided), especially when the spine and pelvis are involved. An FDG PET scan is performed to identify any additional metastasis in the body.
Identification of metastasis and staging of primary cancer provides information on the burden of disease in the body and expected survival in addition to functional disability based on bone/bones involved. Breast, prostate cancer metastasis have a relatively longer survival rate to the thyroid, kidney, lungs, and intestines due to the tendency to spread slowly.
What is the role of Surgical Management in Bone Metastasis?
Surgical Intervention for bone metastasis have gained acceptance and popularity due to increased awareness, the functional demand of the individual, improving surgical expertise, and continuous improvements in implants and prosthesis to treat such bone metastasis.
The aim of the surgical procedure would be curative or palliative depending on the primary cancer and the systemic burden/spread.
Most often, bone metastasis requires palliative surgeries to prolong life and improve the quality of life during this period, often in association with adjuvant therapy.
When is surgery indicated in Bone Metastasis?
The following situations require surgical intervention:
Pathological fractures
Impending pathological fractures- in view of the compromised or weakened structure of a weight-bearing bone.
Single or dual bone metastasis
Disabling pain secondary to metastasis
Extensive involvement of surrounding soft tissues
Compression of spinal cord leading to weakness of limbs
What are the surgical options available for treating Bone Metastasis?
A single or dual bone metastasis is amenable to surgery, especially when the expected disease course is slow and the individual has a comparatively long survival. Such oligometastatic situations requiring surgical interventions have been shown to even prolong survival, acting as a curative option in Metastasis from cancers of breast, prostate, kidney and thyroid.
The current surgical options include Tumour Endoprosthetic reconstruction (Joints of Diaphyseal), Interlocking nailing of long bones and Plate-Cement reconstruction.
Tumour endoprosthetic reconstruction has the advantage of allowing immediate postoperative weight-bearing ambulation. The ability to ambulate and perform daily activities improves self-confidence thereby attending to the psychological and social issues post Metastasis. It also reduces the risk of deep vein thrombosis, pressure sores, depression, pneumonia, constipation etc. which can happen when one is bedridden.
Interlocking intramedullary nailing of long bones with or without cement is performed for metastasis in the long bone of the upper limb, an impending pathological fracture in upper and lower limb bones, and chronic pain with extensive bone metastasis. This procedure is relatively inexpensive when compared to tumour endoprosthetic reconstruction and is a viable option in multiple bone metastasis setting. The limitations are delayed weight-bearing ambulation, the persistence of pain, as well as a delayed and variable healing process of metastatic bone, all of which reduce the functional status of the patient in comparison to tumour endoprosthetic reconstruction. Often, situations needing interlocking nailing or plating require the addition of radiotherapy to the affected area to provide pain palliation and also help heal the affected bone.
What are the surgical options available for Spine Metastasis?
Metastasis to the spine resulting in spinal cord compression or vertebral body collapse require surgical intervention in the form of decompression and instrumentation with pedicle screws. This is often an emergency procedure required to relieve the cord compression and prevent worsening of the weakness or of neurological deficits. Isolated or multiple vertebral metastases may require radiotherapy or vertebroplasty/kyphoplasty depending on the severity of the bone involvement. In case of any associated deformity or impeding collapse, surgical intervention in the form of instrumentation may be required to ambulate the individual.
What other adjuvant treatment is required to treat Bone Metastasis?
The role of adjuvant treatment is based on primary cancer and can be as follows:
Chemotherapy
External Beam Radiotherapy (EBRT)
Arterial Embolization
Radiofrequency Ablation
High-Frequency Ultrasound may be provided based on primary cancer and treatment status.
Dr Srimanth B S
M.S, D.N.B Orthopaedics
Fellowship in Musculoskeletal Oncology (SNUH-Korea, Rizzoli-Italy, TMH-Mumbai)
Musculoskeletal Oncosurgeon
Manipal Hospitals
