肺癌根治手術後に発生した異時性肺癌に対する縮小手術

Sublobar Resection for Patients with a Metachronous Second Primary Lung Cancer Following Curative Resection of a Primary Lung Cancer

近年，画像診断技術の向上やCT検診の普及率は著しく，従来と比較して早期肺癌例が多く発見されるようになった．そこに高齢化社会の進行が伴って，根治的肺切除後の長期生存例は今後ますます増加していくと思われる．一方，肺癌切除後の長期生存は異時性肺癌発生のリスクを孕んでおり，肺切除後の非小細胞肺癌（NSCLC）例では，年に1～2％の確率で異時性多発肺癌を発症するとされている1，2）．しかしながら，肺切除後の症例に対しては，心肺機能の低下，加齢，全身化学療法による合併症などの理由から，しばしば縮小手術の選択を余儀なくされる．肺癌術後の異時性多発肺癌は，当科での検討も含め切除可能であれば42～65％の5年生存率が得られると報告されているが3～6），手術適応や術式選択には議論の余地があり，症例蓄積が必要である．われわれは，肺癌の根治切除後に発生した異時性肺癌に対する縮小手術例の治療成績と安全性について検討を行った．

Background：Surgical methods for patients with a metachronous 2nd primary lung cancer following curative resection of a primary lung cancer remain controversial. The purpose of this study was to evaluate the outcomes of patients who underwent sublobar resection for a metachronous 2nd primary lung cancer.

Methods：We retrospectively analyzed 10 patients who underwent sublobar resection for a metachronous 2nd primary lung cancer occurring 5 years or more after the initial surgery for primary lung cancer.

Results：The 5-year overall survival rate after the 2nd surgery was 68.6％. There was no operative mortality. A postoperative recurrence developed in 4 patients, 3 of whom had pathological stage ⅠA3 cancer. Moreover, patients with a stage ⅠA3 metachronous 2nd primary lung cancer had significantly lower 5-year disease-free and overall survival rates than patients with a stage ⅠA1 or ⅠA2 cancer （disease-free survival rate, p＝0.022；overall survival rate, p＝0.023）.

Conclusions：For patients with a stage ⅠA1 or ⅠA2 metachronous 2nd primary lung cancer, sublobar resection may be acceptable because those patients had a good prognosis in this study. Early detection of a metachronous 2nd primary lung cancer following the initial surgery may be very important for improving the patient’s prognosis.