Progesterone-receptor index in meningiomas: correlation with clinico-pathological parameters and review of the literature

For recurrent and untreatable meningiomas alternative therapies, such as anti-progesterone treatment, have been sought. However, the few clinical studies have not determined progesterone receptor (PgR) expression in most cases, and studies correlating quantitative PgR expression (PgR index) with clinico-pathological variables are scarce. The aim of our study was to assess the PgR indices in a consecutive series of meningiomas and correlate these values with clinico-pathological parameters. We analyzed immunohistochemically 82 consecutive meningioma specimens (73 primary and nine recurrent tumors) for PgR and Ki-67 antigen (MIB-1). The male/female ratio was 1: 1.7, and median age at the time of surgery was 57 years (range 29-77 years). The series comprised 55 grade I (subtyped as 36 meningothelial, seven fibrous, nine transitional, two psammomatous, and one angiomatous), 23 grade II, and one grade III meningiomas. Nuclear immunostaining for PgR was positive in 56 meningioma specimens (71%). PgR index was 21.4 +/- 2.8% (mean +/- SE; range 0-79%). Significantly higher expression was found in male patients in the age group <50 years than in those ≥60 years and in grade I meningothelial meningiomas than in fibrous and transitional subtypes. There was a trend to lower PgR indices in non-benign meningiomas. Cell proliferation rate (MIB-1 index) was 4.4 +/- 0.4% (mean +/- SE; range 0.3-15.4%). Significantly higher MIB-1 indices were found in male than female patients,in recurrent than primary and in grade 11 than grade I meningiomas. We observed a trend to higher PgR indices in meningiomas with MIB-1 index <5%. In sum, the highest PgR index in our series was observed in patients under the age of 50 years with WHO grade I meningiomas of the meningothelial subtype and low cell proliferation indices. If hormonal therapy has a direct action on the PgR, these patients should respond best to anti-progesterone treatment. We conclude that PgR index is variable in meningioma, depending on clinical parameters and histopathological features. Stratification of anti-progesterone therapy trials on the basis of PgR index should be considered.