Two tests help determine the source of cancer cells for bone metastasis

For patients with bone metastases of unknown origin, imaging evaluation, case history, and immunohistochemistry can help determine the origin of the cancer cells.

Radiographic evaluation

Most patients with bone metastases of unknown origin are diagnosed through imaging evaluation. The examination sites are mainly concentrated in the chest and abdominal organs, and the examination methods mainly include plain films, B-ultrasound and CT. Among them, chest X-ray plain films have the advantages of simplicity, economy and high detection rate, and can find 33%~43% of primary lesions; B-ultrasound examinations of the abdomen, pelvis and urinary system also have similar advantages and can find a considerable number of primary tumors; CT examinations can find more lesions, and abdominal and pelvic CT can find 30%~35% of primary tumors.

If the primary tumor is still not found after the above examinations, a biopsy or postoperative pathological examination is required to confirm the diagnosis. In most cases, ordinary pathological results can only confirm the diagnosis of metastatic cancer, and rarely can the primary cancer site be identified. Immunohistochemistry can obtain some information about the primary tumor, especially the distinction between undifferentiated tumors. Combined with clinical history and other examinations, it can distinguish the source of tumor cells in up to 72% of patients. Combining immunohistochemical examinations such as CK7, CK20, CAl25, CEA, TTF21, etc. can effectively diagnose tumors that are difficult to distinguish, such as lung cancer, colon adenocarcinoma and ovarian cancer. The overall pathological diagnosis positive rate is 66.4%, but the confirmation rate of pathological examination alone is only 42.4%. Therefore, it is not advisable to rely too much on pathology, and the diagnosis must be made in combination with pathological results based on certain auxiliary examinations.