前立腺癌に対する11C-choline PETの経験:原発巣および転移巣の検出について

Abstract

2000～2005年までの前立腺癌23例(初発群13例, 根治的療法後生化学的に再発を来した再発群10例)に対し11C-choline PET撮像を行い, その結果について検討した。1)前立腺のSUVは初発群で平均5.78, 対照群では平均3.19であった。初発群と対照群で重複する部分はあるが, SUV 3.8以上は全例前立腺癌症例で, SUV 3.8をcut offとすると感度64.3%, 特異度100%であった。2)初発群では71%に前立腺内のhot spotを認め, Hot spotの有無による感度は75.0%, 特異度は71.4%であった。更にSUV 3.8以上, hot spotの有無と併せて検討すると感度92.9%, 特異度75%まで診断効率が向上した。3)再発群では, リンパ節再発4例, 骨再発3例はすべて11C-choline PETで検出可能であったが, 局所再発4例中2例, 他検査を含めて再発部位を検出できなかった2例では再発部位を検出できなかった。4)再発群に対する11C-choline PETの検出感度は58.8%, 特異度100%であった。また, 撮影時PSA 2.3ng/ml以下ではPET陽性例は検出されなかった。

A total of 33 11C-choline positron emission tomography scans for 23 patients with prostate cancer were performed to elucidate the localization of primary site within the prostate gland (primary group) and of recurrent site after radical treatment (recurrent group) from 2000 to 2005. As a control group, one scan for benign prostate hyperplasia and 3 scans for bladder cancer were also studied. Mean PSA values of 14 scans in the primary group and 19 scans in the recurrent group were 39.8 ng/ml (range 1.6-150) and 5.0 ng/ml (range < 0.2-11), respectively. The primary cancer could be visualized as a hot spot within the prostate gland in 10 out of 14 scans and histopathological analysis of biopsy and prostatectomy specimens verified the correct laterality. Positive scans were demonstrated in 2 out of 4 local recurrent sites, 4 out of 4 lymph node recurrent sites and 4 out of 4 bone recurrent sites with a mean PSA value of 6.22 ng/ml (range 2.3-11). Four scans with a PSA value of 2.3 ng/ml or less, no positive spot was demonstrated. These 4 scans consisted of 2 false negative and 2 true negative studies. 11C-choline PET seems to be useful to detect primary prostate cancer and could play a complementary role for conventional imaging methods in recurrent site staging.