目的：輔助性化療 (adjuvant chemotherapy, ACT) 有助於改善第三期大腸癌病人經手術切除原發部位腫瘤後的存活，然而早年臨床試驗中僅納入少數75 歲以上病人，且老年族群受限於生理機能改變、共病偏多與餘命有限，因此ACT 對於75 歲以上族群的效益尚有待證實。本研究欲探討ACT 對於75 歲以上第三期大腸癌病人存活之影響。
方法：以衛生福利部健康資料中心所提供之全人口全民健康保險研究資料庫執行回溯性觀察性研究，納入2009 ~ 2010 年75 歲以上經手術切除原發部位腫瘤第三期大腸癌病人，分為未使用ACT、fluoropyrimidine-based ACT 與oxaliplatin-based ACT 三組。使用ACT 個案需於術後6 個月內開始接受治療。研究指標為癌症相關存活，使用競爭死因分析搭配治療傾向分數權重評估ACT 在各組間的治療效益。
結果： 共納入1,030 位個案， 其中27.5% 未使用ACT， 使用ACT 種類以fluoropyrimidine-based ACT 為主。競爭死因分析結果為fluoropyrimidine-based ACT 與oxaliplatin-based ACT 相較於未使用ACT 其癌症相關死亡校正後風險比 (adjusted hazard ratio, aHR) 分別為0.508 (95% 信賴區間 = 0.432 ~ 0.598) 與0.427 (95% 信賴區間 = 0.334 ~ 0.545)。
結論：75 歲以上經手術切除腫瘤之第三期大腸癌病人，術後若能積極使用ACT可能有助於改善癌症相關存活。

Objective: In the 1990s, adjuvant chemotherapy (ACT) for stage III colon cancer was shown to improve survival. However, only a small proportion of elderly patients, especially those ≥ 75 years old, were included in clinical trials. There is no general agreement that ACT should be offered to the elderly since they may have a shorter life expectancy and comorbid conditions. In this study, we aim to determine whether ACT improves the survival of patients ≥ 75 years old with stage III colon cancer.
Methods: This is a retrospective cohort study using the Taiwan National Health Insurance Research Database. Selected patients were: (1) diagnosed with stage III colon cancer and received curative resection, and (2) aged ≥ 75 years old at diagnosis between 2009 and 2010. All included patients were divided into three groups: notreatment, fluoropyrimidine-based ACT, and oxaliplatin-based ACT. ACT was delivered within six months after curative resection. Our study outcome was cancer-specific survival and competing risk analyses adjusted for propensity score weighting were conducted to analyze the outcomes in different groups.
Results: Out of 1,030 patients, 266 (27.5%) were not treated after surgery. More patients received fluoropyrimidine-based ACT than oxaliplatin-based ACT. Competitive risk analysis revealed ACT was an independent predictor of better cancer-specific survival (adjusted hazard ratio [aHR] = 0.508, 95% confidence interval [CI] = 0.432~0.598 for fluoropyrimidine-based ACT; aHR = 0.427, 95% CI = 0.334~0.545 for oxaliplatin-based ACT).
Conclusions: Patients ≥ 75 years old with stage III colon cancer who underwent curative resection had better survival outcomes after receiving adjuvant chemotherapy than those who did not.

Summited for publication: 2020.4.13; Accepted for publication: 2020.8.27