tumor markers
...that tumor markers are chemical substances found in blood that arise from the presence of cancerous tissues?
...that <b id="mwAak"><a href="./Tumor_marker" id="mwAao" rel="mw:WikiLink" title="Tumor marker">tumor markers</a></b> are chemical substances found in <a href="./Blood" id="mwAas" rel="mw:WikiLink" title="Blood">blood</a> that arise from the presence of <a href="./Cancer" id="mwAaw" rel="mw:WikiLink" title="Cancer">cancerous</a> <a class="mw-disambig" href="./Tissue" id="mwAa0" rel="mw:WikiLink" title="Tissue">tissues</a>?