Immunohistochemistry in diagnosis and surgical treatment of femoral bone metastasis.

Background: When the primary tumor is unknown, the biopsy and the histopathological examination (associated with immunohistochemistry and molecular profiling) will identify the type and subtype of the tumor and, if possible, the site of origin. The classification in type and subtype will allow to assess the prognosis and to indicate the most appropriate therapeutic approach.

Aim: Identification of the unknown primary tumor by biopsy and immunohistochemistry from the femoral bone metastasis, the clinical results and the survival rate after osteosynthesis ± cement stabilization of the lesion.

Patients And Methods: 52 patients with femoral metastasis were included in a prospective study. The gender ratio was 30 women/22 men (average age - 64 years and six months; range: 33-82 years). Thirty-three patients had pathologic bone fracture, while 19 had osteolytic lesions without fracture. The mean follow-up for survivors was 34 months (range: 17-56 months). Surgical treatment consisted in hemiarthroplasty, osteosynthesis with DHS (Dynamic Hip Screw), proximal femoral nail, locked centromedullary nail or DCS (Dynamic Condylar Screw) ± cement. In 19 (36.54%) cases, the primary tumor was not known. In these cases, biopsy and histological examination with immunochemistry were performed. Twenty-three (52.27%) patients underwent chemotherapy. Clinical and radiological check-ups were performed every three months in the first year and every six months after that.

Results: Pain was ameliorated in all cases. Deambulation was achieved in 45 out of 52 (86.54%) patients. Survival rate was 76.92% (40/52) at six months and 59.61% (31/52) at 12 months. At the end of the follow-up period, 18 (34.61%) patients were alive, 24 (46.15%) were deceased and 10 (19.23%) were lost to follow-up. After eliminating the patients lost to follow-up, the survival rate was 33.33% (9/27) in the pathologic fracture group and 60% (9/15) in the osteolytic lesion without fracture group.

Conclusions: Most of the patients (86%) could be mobilized immediately after surgery. The expected survival rate one year after surgery is around 60%. The goals of osteosynthesis are the same, regardless the location of the lesion and the implant used: pain amelioration, appropriate stability for immediate full weight bearing, durability for patient's life expectancy. All extended osteolytic lesions must be reinforced at the time of the surgical procedure. The presence of a pathologic fracture is a negative prognosis factor for the medium term survival rate.