Liver Unit, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, United Kingdom.
J Hepatol. 2012 Apr;56(4):848-54. doi: 10.1016/j.jhep.2011.11.015. Epub 2011 Dec 13.
BACKGROUND & AIMS: Cholangiocarcinomas (CC) can be sub-divided into intrahepatic (IHCC) or extrahepatic (EHCC). Hilar or 'Klatskin' tumours are anatomically extrahepatic. Most international studies, also from the UK, report increasing IHCC and decreasing EHCC incidence. The second edition of the International Classification of Diseases for Oncology (ICD-O-2) assigned 'Klatskin' tumours a unique histology code (8162/3), but this was cross-referenced to the topography code for intrahepatic (IHBD) rather than extrahepatic bile duct tumours (EHBD). Under the third ICD-O edition, 'Klatskin' tumours are cross-referenced to either IHBD or EHBD. New editions of the ICD-O classification are adopted at different time points by different countries. We investigated the impact of changing ICD-O classifications and the potential misclassification of hilar/'Klatskin' tumours on bile duct tumour and CC incidence rates in England and Wales and the US. We also examined whether coding practices by cancer registries in England and Wales could be influencing these rates.
We analysed age-standardised incidence rates (ASIR) in England and Wales for IHBD and EHBD tumours between 1990 and 2008, then transferred all 'Klatskin' tumours from IHBD to EHBD and reanalysed rates from 1995, when ICD-O-2 was introduced in the UK. We also compared trends in IHBD, EHBD, and 'Klatskin' tumours in England and Wales with those in the USSEER (Surveillance, Epidemiology and End Results) database. Coding practice at Cancer registry level in England and Wales was investigated via a questionnaire completed by all national cancer registries.
In England and Wales, 1990-2008, ASIR of IHBD cancers rose (0.43-1.84/100,000 population in males; 0.27-1.51 in females) but fell for EHBD (0.78-0.51/100,000 population in males; 0.62-0.39 in females). After transferring all 'Klatskin' tumours from IHBD to EHBD, there remained a marked increase in ASIR of IHBD cancers and a decrease in ASIR for EHBD, as only 1% of CC were reportedly 'Klatskin'. The US SEER data showed that ASIR for IHBD gradually rose from 0.59/100,000 population in 1990 to 0.91 in 2001, then sharply fell before plateauing at 0.60 by 2007. ASIR for EHBD remained relatively stable at around 0.80/100,000 population until 2001, then began increasing, to 0.97 by 2007. Annually, between 1995 and 2008, the vast majority of 'Klatskin' tumours in England and Wales were coded as IHBD. This was also the case in the SEER data until 2001, when the situation was reversed and subsequently most 'Klatskin' tumours were coded as EHBD. US trends coincide with a switch from ICD-O2 to ICD-O-3 in 2001. In the UK, the switch to ICD-O-3 only occurred in 2008. On questioning, cancer registries in England and Wales stated they would not code a CC described as 'hilar' with the designated 'Klatskin' histology code. If the tumour site is unspecified, most registries classify CC as intrahepatic.
Changes in ICD-classification may be influencing observed changes in IHBD and EHBD incidence rates. Coding misclassification is likely to have been skewing CC registration to an intrahepatic site, thereby contributing to the previously reported rise in intrahepatic tumours.
胆管癌（CC）可分为肝内（IHCC）或肝外（EHCC）。肝门部或“Klatskin”肿瘤在解剖学上是肝外的。大多数国际研究，包括来自英国的研究，报告 IHCC 的发病率增加，EHCC 的发病率降低。国际肿瘤疾病分类（ICD-O-2）的第二版为“Klatskin”肿瘤分配了一个独特的组织学代码（8162/3），但这与肝内（IHBD）而不是肝外胆管肿瘤（EHBD）的解剖代码交叉引用。根据 ICD-O-3 版，“Klatskin”肿瘤交叉引用 IHBD 或 EHBD。不同国家采用 ICD-O 分类的新版本的时间不同。我们调查了 ICD-O 分类变化以及对肝门部/“Klatskin”肿瘤的潜在错误分类对英格兰和威尔士以及美国的胆管肿瘤和 CC 发病率的影响。我们还检查了英格兰和威尔士癌症登记处的编码实践是否会影响这些比率。
我们分析了 1990 年至 2008 年间英格兰和威尔士 IHBD 和 EHBD 肿瘤的年龄标准化发病率（ASIR），然后将所有“Klatskin”肿瘤从 IHBD 转移到 EHBD，并从 1995 年重新分析，当时 ICD-O-2 在英国推出。我们还比较了英格兰和威尔士与美国 SEER（监测、流行病学和最终结果）数据库中 IHBD、EHBD 和“Klatskin”肿瘤的趋势。通过所有国家癌症登记处完成的问卷调查了英格兰和威尔士癌症登记处的编码实践。
在英格兰和威尔士，1990-2008 年，IHBD 癌症的 ASIR 上升（男性为 0.43-1.84/100,000 人口；女性为 0.27-1.51），而 EHBD 则下降（男性为 0.78-0.51/100,000 人口；女性为 0.62-0.39）。将所有“Klatskin”肿瘤从 IHBD 转移到 EHBD 后，IHBD 癌症的 ASIR 仍显著增加，EHBD 的 ASIR 下降，因为据报道只有 1%的 CC 是“Klatskin”。美国 SEER 数据显示，IHBD 的 ASIR 从 1990 年的 0.59/100,000 人口逐渐上升到 2001 年的 0.91，然后急剧下降，到 2007 年达到 0.60 的平台期。EHBD 的 ASIR 保持相对稳定，约为 0.80/100,000 人口，直到 2001 年，然后开始增加，到 2007 年达到 0.97。1995 年至 2008 年期间，英格兰和威尔士的绝大多数“Klatskin”肿瘤被编码为 IHBD。直到 2001 年，SEER 数据也是如此，然后情况发生了逆转，随后大多数“Klatskin”肿瘤被编码为 EHBD。美国的趋势与 2001 年从 ICD-O2 切换到 ICD-O-3 相符。在英国，仅在 2008 年才切换到 ICD-O-3。在询问中，英格兰和威尔士的癌症登记处表示，他们不会将被描述为“肝门部”的 CC 编码为指定的“Klatskin”组织学代码。如果肿瘤部位未指定，大多数登记处将 CC 归类为肝内。
ICD 分类的变化可能会影响 IHBD 和 EHBD 发病率的变化。编码错误分类可能会导致 CC 登记偏向肝内部位，从而导致先前报告的肝内肿瘤增加。
