University Medical Centre Maribor, Maribor, Slovenia.
Radiol Oncol. 2011 Jun;45(2):75-81. doi: 10.2478/v10019-011-0005-8. Epub 2011 Mar 15.
Colorectal cancer (CRC) is the third most common cancer in the world. In 75% CRC develops sporadically, in 25% hereditary or as a consequence of inflammatory bowel disease. CRC carcinogenesis develops over many years. The cause of CRC in 85% is chromosomal instability (CIN) and in 15% microsatellite instability (MSI-H), where hereditary nonpolyposis colorectal cancer (HNPCC) represents 10-20%. Microsatellite sequences (MS) are repeated sequences of short stretches of DNA all over the genome. Microsatellite stability (MSS) means MS are the same in each cell of an individual, whereas microsatellite instability (MSI-H) means MS differ in normal and cancer cells of an individual. The cause of MSI-H is a damaged mismatch repair mechanism (MMR), with the most important MMR proteins being MSH2, MLH1 and MSH6.
MSI-H seems to be an important prognostic factor in CRC and an important predictive factor of CRC chemotherapeutic treatment efficacy. Clinical trials conducted until now have shown contradictory findings in different chemotherapeutic settings, adjuvant and palliative; therefore MSI-H is going to be the object of the future research. The future of cancer treatment is in the individualized therapy based on molecular characteristics of the tumour, such as MSI-H in CRC.
结直肠癌（CRC）是世界上第三大常见癌症。75%的 CRC 是散发性的，25%是遗传性的，或是炎症性肠病的后果。CRC 癌变的发展需要很多年。CRC 发病原因 85%是染色体不稳定性（CIN），15%是微卫星不稳定性（MSI-H），其中遗传性非息肉病性结直肠癌（HNPCC）占 10-20%。微卫星序列（MS）是基因组中短 DNA 片段的重复序列。微卫星稳定性（MSS）意味着个体中每个细胞中的 MS 是相同的，而微卫星不稳定性（MSI-H）意味着个体中正常细胞和癌细胞中的 MS 不同。MSI-H 的原因是受损的错配修复机制（MMR），最重要的 MMR 蛋白是 MSH2、MLH1 和 MSH6。
MSI-H 似乎是 CRC 的一个重要预后因素，也是 CRC 化学治疗疗效的一个重要预测因素。迄今为止进行的临床试验在不同的化疗环境中，辅助和姑息治疗中得出了相互矛盾的结果；因此，MSI-H 将成为未来研究的对象。癌症治疗的未来在于基于肿瘤分子特征的个体化治疗，如 CRC 中的 MSI-H。
