Koketsu Shinichiro, Watanabe Toshiaki, Tada Tomohiro, Kanazawa Takamitsu, Ueda Eiji, Nagawa Hirokazu
Department of Surgical Oncology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, Japan 113-8655.
Hepatogastroenterology. 2003 Nov-Dec;50(54):1749-52.
BACKGROUND/AIMS: The mechanism of the development of cancer in old age is not well understood in various cancers, especially colorectal cancer. Colorectal cancer in elderly patients often shows a high frequency of proximal colon cancer. Microsatellite instability cancers are often found in the proximal colon and show a lower incidence of p53 abnormality. While the aberrant expression of p53 is more frequent in the distal colon. To investigate the carcinogenesis of colorectal cancer in elderly patients, we studied the genetic background of these patients regarding microsatellite instability and the aberrant expression of p53.
In the present study, we examined the clinicopathological features and the frequency of p53 abnormality in elderly patients compared to younger patients, and the frequency of microsatellite instability in elderly patients. In microsatellite instability cancer, immunoreactivity of hMSH2 and hMLH1 were also examined.
Colorectal cancer in elderly patients is associated with proximal location of the cancer (p = 0.008). Microsatellite instability was observed in only 1 case (2.8%). The immunoreactivity of hMLH1 showed negative staining in malignant glands. The frequency of aberrant expression of p53 showed no significant difference between two groups.
We found colorectal cancer more frequently in proximal colon in elderly patients than in younger patients, and microsatellite instability frequency in elderly patients (2.8%) was lower than reported microsatellite instability frequency in sporadic colorectal cancer patients. Moreover, the frequency of aberrant expression of p53 did not differ between the two groups. In the present study, microsatellite instability appeared to be less important for the carcinogenesis of colorectal cancer in elderly patients as compared to younger patients.
背景/目的：在各种癌症中，尤其是结直肠癌，老年癌症发生的机制尚未完全明确。老年患者的结直肠癌通常表现为近端结肠癌的高发生率。微卫星不稳定癌症常发生于近端结肠，且p53异常的发生率较低。而p53的异常表达在远端结肠更为常见。为了研究老年患者结直肠癌的致癌机制，我们研究了这些患者在微卫星不稳定和p53异常表达方面的遗传背景。
在本研究中，我们检查了老年患者与年轻患者相比的临床病理特征和p53异常的发生率，以及老年患者微卫星不稳定的发生率。对于微卫星不稳定癌症，还检测了hMSH2和hMLH1的免疫反应性。
老年患者的结直肠癌与癌症的近端位置相关（p = 0.008）。仅1例（2.8%）观察到微卫星不稳定。hMLH1的免疫反应性在恶性腺体中呈阴性染色。两组之间p53异常表达的发生率无显著差异。
我们发现老年患者近端结肠癌的发生率高于年轻患者，且老年患者的微卫星不稳定发生率（2.8%）低于散发性结直肠癌患者报道的微卫星不稳定发生率。此外，两组之间p53异常表达的发生率没有差异。在本研究中，与年轻患者相比，微卫星不稳定在老年患者结直肠癌的致癌过程中似乎不那么重要。
