Bhansali M S, Patil P K, Badwe R A, Havaldar R, Desai P B
Department of Thoracic Oncology, Tata Memorial Centre, Bombay, India.
Dis Esophagus. 1997 Jan;10(1):51-4. doi: 10.1093/dote/10.1.51.
Conclusion based on historical controls are known to be fallible in assessing efficacy of treatment due to selection bias. Historical controls have been repeatedly used in investigating efficacy of newer treatment avenues in esophageal cancer. The aim of the study was to assess the efficacy of adjuvant chemotherapy in esophageal cancer after correction for an historical control bias.
The database of 433 patients treated surgically for cancer of the esophagus at our institute between 1980 and 1989 was analyzed. The analysis was carried out using the Cox model for known prognostic factors without any correction for historical bias. Database was reanalysed after introducing registration year as a variable in the model to correct for historical control bias, which was further examined by carrying out a case-control study comparing chemotherapy (n = 83) vs contemporary control (n = 164) matched for lymph-node status, age and sex randomly selected from the same database.
The analysis without correction for historical control bias showed lymph-node metastasis (P = 0.000), female sex (P = 0.002), depth of invasion (P = 0.001) and adjuvant chemotherapy (P = 0.03) as significant predictors of survival. On introduction of registration year as a variable, lymph-node metastasis, sex and depth of invasion continued to be significant factors but chemotherapy was replaced by registration year (P = 0.02). The database with contemporary control showed lymph-node metastasis (P = 0.000), depth of invasion (P = 0.008) and female sex (P = 0.001) as significant factors. Chemotherapy had no effect on survival.
Results from historical controls are unreliable in detecting modest treatment benefits. Adjuvant chemotherapy in esophageal cancer should be tested within the tenets of randomized controlled trials with adequate-sample size to ascertain its efficacy.
由于选择偏倚，基于历史对照得出的结论在评估治疗效果时已知是不可靠的。历史对照已被反复用于研究食管癌新治疗途径的疗效。本研究的目的是在校正历史对照偏倚后评估辅助化疗在食管癌中的疗效。
分析了1980年至1989年期间在我院接受食管癌手术治疗的433例患者的数据库。使用Cox模型对已知的预后因素进行分析，未对历史偏倚进行任何校正。在模型中引入登记年份作为变量以校正历史对照偏倚后，对数据库进行了重新分析，并通过进行一项病例对照研究进一步检验，该研究比较了从同一数据库中随机选择的、淋巴结状态、年龄和性别相匹配的化疗组（n = 83）与当代对照组（n = 164）。
未校正历史对照偏倚的分析显示，淋巴结转移（P = 0.000）、女性（P = 0.002）、浸润深度（P = 0.001）和辅助化疗（P = 0.03）是生存的显著预测因素。引入登记年份作为变量后，淋巴结转移、性别和浸润深度仍然是显著因素，但化疗被登记年份所取代（P = 0.02）。当代对照的数据库显示，淋巴结转移（P = 0.000）、浸润深度（P = 0.008）和女性（P = 0.001）是显著因素。化疗对生存没有影响。
历史对照的结果在检测适度的治疗益处方面不可靠。食管癌的辅助化疗应在随机对照试验的原则内进行测试，样本量要足够大，以确定其疗效。
