PSA4.0-10.0ng/ml症例に対する前立腺生検におけるBody mass indexの臨床的意義

Abstract

2005年4月～2007年9月に前立腺生検を受け, PSAが4.0～10.0ng/mlであった305例(年齢48～88歳)を対象に行った経直腸的生検における陽性群と陰性群を比較検討した。またBMI値を22kg/m2未満, 22～25kg/m2, 25kg/m2以上の3群に分類して検討した。305例中127例(42%)が前立腺癌と診断され, 陽性群と陰性群の比較では陽性群は前立腺体積が有意に小さく, BMIに有意差は認めなかった。BMIで分類した3群におけるPSA値, 前立腺体積, 癌検出率に有意差は認めないが, BMIの高値群では年齢が低かった。年齢の上昇は前立腺癌の検出危険度を上昇させ, 前立腺体積の増加は検出危険度を減少させた。癌の広がりに関して, 有意に関連する因子は認められなかった。癌の悪性度評価がgleason score 4+3以上であることとBMIの上昇には有意な関連を認めた。以上より, PSA 4.0～10.0ng/mlの症例においてBMIは癌検出率に寄与する因子とはならなかったが, BMI高値の症例では癌の悪性度が高い可能性が示唆された。

From April 2005 to September 2007, 480 patients underwent transrectal prostate biopsy at our institution. The clinical data including age, serum prostate specific antigen (PSA) level, prostate volume and body mass index (BMI) were obtained, and the cancer detection rates and pathological findings were evaluated in 305 cases with a PSA concentration of 4.0 to 10.0 ng/ml. Prostate volume was calculated from magnetic resonance imaging (MRI) findings. The 305 patients were categorized according to their BMI into three groups (normal, less than 22 kg/m2 ; overweight, 22-25 kg/m2 ; and obese, more than 25 kg/m2). Cancer detection rates and histopathologic findings were compared between the groups. Multivariate logistic regression analysis was also performed. Prostate cancer was detected in 127 patients. No significant differences in BMI were observed between biopsy-positive and biopsy-negative cases (p = 0.965), and the detection rates of prostate cancer observed in the three groups were not significantly different. There was a significant association between BMI and the findings of high Gleason score (more than 4+3) (p = 0.048). BMI was not a contributory factor of prostate cancer detection for cases with intermediate PSA levels; however, patients with high BMI may have high-grade malignancy features.