▁ep ith el ial ▁can cers ▁( bre ast , ▁pro state , ▁lung , ▁and ▁colon ) ▁and ▁clin ical ▁ev id ences ▁indicate ▁that ▁patients ▁with ▁met ast atic ▁les ions ▁are ▁more ▁likely ▁to ▁have ▁C TC s ▁isolated . ▁ ▁C TC s ▁are ▁usually ▁( in ▁ 2 0 1 1 ) ▁captured ▁from ▁the ▁vas cul ature ▁by ▁using ▁specific ▁ant ib od ies ▁able ▁to ▁recognize ▁specific ▁tum oral ▁marker ▁( us ually ▁Ep C AM ); ▁however ▁this ▁approach ▁is ▁bi ased ▁by ▁the ▁need ▁for ▁a ▁sufficient ▁expression ▁of ▁the ▁selected ▁protein ▁on ▁the ▁cell ▁surface , ▁event ▁necessary ▁for ▁the ▁en rich ment ▁step . ▁Moreover , ▁since ▁Ep C AM ▁and ▁other ▁prote ins ▁( e . g . ▁cy to ker at ins ) ▁are ▁not ▁expressed ▁in ▁some ▁tum ors ▁and ▁can ▁be ▁down ▁reg ulated ▁during ▁the ▁ ▁ep ith el ial ▁to ▁mes en ch ym al ▁transition ▁( E MT ), ▁new ▁en rich ment ▁strateg ies ▁are ▁required . ▁ ▁First ▁evidence ▁indicates ▁that ▁C TC ▁markers ▁applied ▁in ▁human ▁medicine ▁are ▁conser ved ▁in ▁other ▁species . ▁Five ▁of ▁the ▁more ▁common ▁markers ▁including ▁C K 1 9 ▁are ▁also ▁useful ▁to ▁detect ▁C TC ▁in ▁the ▁blood ▁of ▁dogs ▁with ▁m align ant ▁m amm ary ▁tum ors . ▁Ne wer ▁approaches ▁are ▁able ▁to ▁identify ▁more ▁cells ▁out ▁ 7 . 5 ▁m l ▁of ▁blood , ▁like ▁I so f F ux