腎癌におけるT分類カットオフ値の再評価  [in Japanese] REASSESSMENT OF T CLASSIFICATION SYSTEM CUTOFF VALUE FOR RENAL CELL CARCINOMA  [in Japanese]

(目的)1997年に腎癌T1/T2カットオフ値が7cmになり,2002年にはT1が4cmでTlaとTlbに細分化された.カットオフ値と予後との関係について当科症例を用いて再評価した.(対象と方法)1985年1月から2004年1月までに開腹根治的腎摘除術を施行した200名の症例に関して評価した.T1/T2カットオフ値評価のため,3cm〜9cmまで1cm区切りにカットオフ値を設定し生存率を算出した.次にT1患者におけるTla/Tlbカットオフ値を評価のため. 3cm〜6cmまで1cm区切りにカットオフ値を設定し生存率を算出した.最後に腫瘍径7cm以上のT2〜3a患者を絹分化するカットオフ値が存在するかを確認するため9cm〜14cmまで1cm区切りにカットオフ値を設定し生存率を算出した.(結果)T1/T2カットオフ値に関しては,7cmまたは8cmが生存率に最も有意な差を認めた.Tla/Tlbカットオフ値では全ての値で有意差は認めなかったが,4cmまたは5cmで最も生存曲線に差を認めた.腫瘍径7cm以上の腫瘍カットオフ値の検討では,13cmでのみ有意差を認めた.(結論)転移なし腎癌における現在のT分類4cmおよび7cmカットオフ値は妥当であると考えられた.また腫瘍径7cm以上の転移なし腎癌におけるカットオフ値は13cmがもっとも有効であった.

(Purpose) The 1997 T staging classification for renal cell carcinoma (RCC) defined Tl as tumors measuring up to 7 cm in size and Tl is subdivided into Tla and Tib with a 4 cm cutoff value in the 2002 TMN classification. We evaluated the validity of these cutoff values by assessing the cancerspecific survival of patients with non-metastatic RCC according to a series of alternative size cutoff values. In addition, we calculated how these size cutoffs affected the disease specific survival rates. (Materials and methods) A database containing the records of 200 patients with RCC who underwent open radical nephrectomy for NOMO disease between 1985 January and 2004 January was evaluated. Tumors were stratified by cutoff values ranging from 3 to 9 cm with the 1 cm increments in order to evaluate whether the 7 cm cutoff value is appropriate. Next, Tl RCC were stratified by cutoff values ranging from 3 to 6 cm with the 1 cm increment in order to verify whether the 4 cm cutoff is appropriate. Lastly, tumors over 7 cm diameter were stratified by cutoff values ranging from 9 to 14 cm with the 1 cm increments in order to verify whether the present T2〜3a categories could be divided according to tumor size. (Results) As for the Tl-2 classification, a cutoff value at 7 cm or 8 cm shared the greatest prognostic power. Although there was no significant difference in T la/Tib subclassification, a 4 cm or 5 cm cutoff value resulted in a greatest separation of survival curves for Tla and Tib. As for tumors from 9-14 cm in diameter, only a 13 cm cutoff value provided a significant difference in survival. (Conclusions) Our results indicate that the present 7 cm cutoff value in the TMN system is valid in terms of prognostic value. The 4 cm cutoff value may not reflect the survival when total nephrectomy is considered, thus indicating that tumors at 4 cm cutoff value may be valid when nephron sparing surgery is considered. The 13 cm cutoff value seems to be most appropriate in NOMO tumors with over 7 cm in diameter.