Population-based study of giant cell tumor of bone in Sweden (1983-2011)

Introduction: Giant-cell tumor of bone (GCTB) is a locally aggressive histologically benign neoplasm with a less common malignant counterpart. Longitudinal data sources on GCTB are sparse, limited to single institution case series or surgical outcomes studies. The Swedish Cancer Registry is one of the few national population-based databases recording GCTB, representing a unique source to study GCTB epidemiology. We estimated incidence rate (IR) and overall mortality rates based on registry data.

Materials and methods: We identified patients with a GCTB diagnosis in the Swedish Cancer Registry from 1983 to 2011: benign (ICD-7 196.0-196.9; PAD 741) and malignant (PAD 746). Results were stratified by age at diagnosis, gender, and anatomical lesion location.

Results: The cohort included 337 GCTB cases (IR of 1.3 per million persons per year). The majority (n=310) had primary benign GCTB (IR of 1.2 per million per year). Median age at diagnosis was 34 years (range 10-88) with 54% (n=183) females. Malignant to benign ratio for women was 0.095 (16/167) and for men 0.077 (11/143). Incidence was highest in the 20-39 years age group (IR of 2.1 per million per year). The most common lesion sites were distal femur and proximal tibia. Mortality at 20 years from diagnosis was 14% (n=48) and was slightly higher for axial (17%; n=6) and pelvic (17%; n=4) lesions. Recurrence occurred in 39% of primary benign cases and 75% of primary malignant cases.

Conclusions: In our modern population-based series primary malignant cases were uncommon (8%), peak incidence 20-39 years with slight predominance in women. Recurrence rates remain significant with overall 39% occurring in benign GCTB, and 75% in malignant form. The linkage between databases allowed the first population based estimates of the proportion of patients who received surgery at initial GCTB diagnosis, and those who also received subsequent surgeries.