OSNA

Colorectal cancer

There are two possible modes of lymph node metastasis in colorectal cancer: the cancer progresses from the primary tumor in order (sequential model), or it skips and causes distant metastasis (skip model). However, lymph node metastasis is usually diagnosed only by HE staining including the maximum cut surface of the lymph node, and micro-lymph node metastasis is not evaluated, so the true mode of lymph node progression is still unclear.
In this study, we used the One-step Nucleic Acid Amplification (OSNA) method to detect micrometastasis by RT-PCR of CK19 mRNA to identify cases of micrometastasis in stage III colon cancer that are pathologically positive for lymph node metastasis, and to clarify the true form of lymph node spread.
If it becomes clear that the true mode of lymphatic progression roughly follows a sequential model, it can be predicted that the prognosis will become worse as lymph node metastasis progresses toward the central region. If this trend is demonstrated in this study, it will provide rationale for the development of new treatments in which extended lymph node dissection with a sufficient range of resection contributes to improving prognosis.

The true mode of lymph node metastasis in colorectal cancer remains unclear. This study aims to clarify the true mode of lymph node metastasis using the OSNA method.

The diagnosis of lymph node metastasis is usually made only by HE staining including the maximum cut surface of the lymph node, and micro lymph node metastasis is not evaluated.
This study aims to clarify the true pattern of lymph node progression by classifying lymph nodes according to the site of lymph node metastasis and analyzing the distribution of lymph node metastasis.

If the true type of lymphatic spread is clarified, it will become rationale for the development of new treatments that will contribute to improving prognosis by providing extensive lymph node dissection with a sufficient extent of resection.

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1. Kataoka K, Beppu N, Shiozawa M et al. Colorectal cancer treated by resection and extended lymphadenectomy: patterns of spread in left- and right-sided tumors. Br J Surg . 2020;107(8):1070-1078.
2. Kataoka K, Ysebaeart H, Shiozawa M, et al. Prognostic significance of number versus location of positive mesenteric nodes in stage iii colon cancer. Eur J Surg Oncol. 2019; 45; 1862-1869
3. Yamamoto H, Tomita N, Inomata M, Furuhata T, Miyake Y, Noura S, et al. OSNA-Assisted Molecular Staging in Colorectal Cancer: A Prospective Multicenter Trial in Japan. Annals of surgical oncology. 2016;23(2):391-6.