Common malignant bone tumors of the limb include osteosarcoma, Ewing sarcoma, chondrosarcoma, etc., which are most common in adolescent patients. Although the incidence rate is not high (the annual incidence rate of osteosarcoma is reported to be 1 per million abroad), the death and disability rates are very high, which brings heavy psychological blow and economic burden to patients and their families, and also brings great economic pressure to the society.
When malignant bone tumor of limb occurs, the traditional treatment is to choose radical or palliative amputation. However, with the progress of adjuvant therapy, especially neoadjuvant chemotherapy, the survival rate and limb preservation rate of limb malignant tumors have been greatly improved in recent years, and the 5-year survival rate has reached 80% in foreign countries and more than 50% in China, and the limb preservation rate has reached 80%-95% in foreign countries.
Treatment goals
The goals of bone tumor treatment are: tumor elimination, long-term patient survival, and limb preservation as much as possible.
Bone tumor treatment is a complete treatment system. It includes preoperative – reasonable biopsy site and mode; clinical imaging pathology diagnosis; correct staging; appropriate adjuvant treatment including neoadjuvant chemotherapy. Intraoperative – selection of the correct resection method; tumor-free technique; reasonable bone and soft tissue reconstruction. Postoperative-Postoperative adjuvant therapy, including evaluation of the effect of preoperative chemotherapy, selection and adjustment of postoperative chemotherapy regimen, selection of radiotherapy and immunotherapy, etc.; and follow-up survival and limb function assessment.
Diagnosis of bone tumor
The diagnosis of bone tumor requires a combination of clinical manifestations, imaging (including conventional X-ray, CT, MRI and DSA, etc.) and pathological examination. Except for some benign lesions such as osteochondroma and osteoid osteoma which can be diagnosed by characteristic X-ray manifestations, most of them need the combination of clinical + imaging + pathology to confirm the diagnosis. Among them, pathological diagnosis is the gold standard for bone tumor diagnosis.
Biopsy method
Biopsy is an important part of bone tumor diagnosis and treatment, and also the only method to make a clear diagnosis before formal surgery.
1.Excisional biopsy: it can obtain enough representative lesion tissues and facilitate pathological diagnosis. However, incisional biopsy has the risk of hematoma and infection at the biopsy site and tumor contamination of the incision. There are also tragedies that patients with limb preservation conditions lose the chance of limb preservation and eventually have to choose amputation due to tumor contamination of the biopsy incision and tumor spread due to improper operation of physicians. For these reasons, the choice of excisional biopsy must be made by a specialist who will perform further radical surgery on the patient, and some teaching hospitals and research centers such as the Sloan-Kettering Cancer Center still perform excisional biopsy as a matter of routine. Standardized biopsy techniques are very important for the diagnosis and subsequent treatment of the disease, and blind biopsy should not be avoided.
2.Closed puncture biopsy: At present, most hospitals and professional doctors advocate closed puncture biopsy for bone tumor patients. The advantage of closed biopsy is to minimize the biopsy channel and reduce the scope of hematoma and tumor tissue contamination. Although the amount of lesion tissue obtained by closed biopsy is small, the diagnostic rate of the disease can still reach more than 80%-90% with proper operation. The former is suitable for soft tissue tumors with rich cellular components and bone marrow tumors; the latter is suitable for substantial bone tumors. x-ray fluoroscopy, CT and B-US can help to locate and improve the accuracy and success rate of puncture biopsy.
Neoadjuvant chemotherapy
Neoadjuvant chemotherapy is crucial to improve limb preservation and survival of patients with malignant bone tumors.
The concept of neoadjuvant chemotherapy was introduced by Rosen in 1982 and includes.
(1) emphasizing the importance of preoperative high-dose chemotherapy, which allows for early systemic chemotherapy with the aim of eliminating microscopic metastases in the lung and improving survival; necrosis and shrinkage of the primary tumor after chemotherapy, which can provide safer margins for limb preservation, improve limb preservation rates and reduce recurrence; and allowing sufficient time to design limb preservation plans and fabricate prostheses.
(2) After removal of the tumor, the necrosis rate can be checked and the postoperative chemotherapy plan can be decided according to the necrosis rate. Clinical practice proves that neoadjuvant chemotherapy is effective. Currently, the 5-year survival rate of osteosarcoma abroad is over 80%, and the limb preservation rate is over 85%; the 10-year survival rate of chondrosarcoma is 65%, and the limb preservation rate is 90%.
Indications for limb-preserving surgery
The nature of the tumor must be clarified according to clinical, imaging and pathology, and the correct staging must be performed before surgery.
Limb-sparing surgery for malignant bone tumors has corresponding indications, including.
(1) Enneking stage IA, IB, IIA and IIB malignant bone tumors with good response to chemotherapy and no major neurovascular involvement in the extremities, pelvis and shoulder;
(2) Good systemic and local soft tissue conditions, capable of radical or extensive resection of the tumor according to the optimal surgical boundaries, and with an expected local recurrence rate no higher than amputation;
(3) Good reconstructive technique and reconstruction conditions, and the function of the reconstructed limb should be better or at least not lower than that of the prosthesis installed after amputation;
(4) Those with no metastases or single metastases that can be cured by extensive resection after systemic chemotherapy;
(5) Patients who require extensive surgical resection due to the ineffectiveness of radiotherapy and chemotherapy alone;
(6) Patients who require limb preservation, have the financial conditions and can actively cooperate with comprehensive treatment.
With the development of medical technology, some of the previous contraindications to limb preservation surgery have become less absolute. With the development of vascular surgery, some patients with bone tumors with major vascular involvement have been given the opportunity to preserve their limbs through revascularization; neoadjuvant chemotherapy has enabled some patients with pathological fractures to have the opportunity to preserve their limbs.
Methods of limb preservation and reconstruction
Currently, the common methods of limb preservation include: artificial prosthesis reconstruction, bone grafting, tumor bone inactivation and reuse, etc.
Artificial prostheses include computer-aided design and manufacturing (CAD/CAM) custom-made prostheses, modular prostheses, and extendable prostheses for children (minimally invasive, non-invasive). The creation of new concepts such as cortical external bridging has improved the stability and survival rate of the use of artificial prostheses. (Cases 1-2 are the cases of bone tumor prosthesis reconstruction and limb preservation surgery performed in our hospital)
Bone grafting includes autologous bone grafting (e.g., autologous fibula graft with vascular tip, free scapular flap) and allogeneic bone grafting. Another better method is the composite reconstruction technique of allograft bone and artificial prosthesis (APC), which takes advantage of the reconstruction of prosthesis and also allows for the reconstruction of ligamentous and tendinous tissue stops using allograft bone ligamentous tendon stops.
Tumor bone inactivation includes chemical methods (liquid nitrogen, pasteurization, etc.), physical methods (radiation inactivation, microwave inactivation), and in situ inactivation of tumor bone (microwave, high-energy ultrasound focusing). (Case 3 is a case of bone tumor bone inactivation and replantation performed in our hospital)
Case 3 Xiao* Male 12 years old Osteosarcoma of the lower left femur with inactivation and internal fixation of the tumor segment The development of limb preservation surgery has enabled many patients to obtain long-term survival while preserving the appearance and function of the limb. However, for those patients with extremely poorly differentiated tumors, large tumor extent, insensitive chemotherapy, and those who cannot achieve the requirement of extensive resection borders, amputation should still be considered as a priority. In the treatment of bone tumors, life-saving and complete removal of the tumor is always the priority, followed by limb preservation.