The circular tumor cells mean the tumor cell floating in the blood.
When the tumor grows, the partial cells are apart from the tumor mass.
And then, their cells go into the vessel and start to flow.
Usually, it is used cytological diagnosis to predict a peritoneum metastasis after stomach cancer.
And recently, RT-PCR of the epitherial markers, such as cytokeratin are thought to be useful technique.
Because the tumor cell is floating in the wash fluid of an abdominal cavity, if the metastatic tumor cell are staying there after surgery.
This news said that new diagnosis methods was shown at the congress of Japanese Surgical Society.
This is the CTCs detection and some CTCs were shown to be detected after stomach cancer surgery.
Therefore, this evaluation could be expected to utilize the diagnosis of a peritoneum metastasis.
血中の遊離癌細胞（CTC）の評価は、腹膜転移の予測因子であり、非侵襲的な診断法として有効である可能性が示唆された。4月12日から千葉県幕張市で開催された第112回日本外科学会定期学術集会で、鹿児島大学腫瘍制御学消化器外科の原口尚士氏が発表した。
http://medical.nikkeibp.co.jp/leaf/all/gakkai/sp/jss2012/201204/524449.html
（中略）
これらの結果から原口氏らは、腹腔洗浄水を対象としたRT-PCRは腹腔洗浄細胞診と比較して遜色のない結果であったが、それ以上に血中CTCの評価は腹膜播種の予測因子として有用性が高く、非侵襲的な腹膜播種診断法として有効である可能性があると締めくくった。
About the breast cancer, the CTCs are detected at the early stage, therefore CTCs detection is expected to become the diagnosis test for metastasis.
Therefore, the detection of living epitherial cells could be a useful biomarker for various tumor metastasis.
