CAREFUL HISTOLOGICAL CONFIRMATION AND MICRODISSECTION REVEAL TELOMERASE ACTIVITY IN OTHERWISE TELOMERASE-NEGATIVE BREAST CANCERS

Studies of invasive breast cancers consistently identify a subset of t umors without telomerase activity, compromising its utility as a tumor marker, Telomerase-negative tumors may represent a biologically diffe rent subset, or the result could be attributed to assay imperfections, To resolve this issue, we tested 105 invasive breast cancers for telo merase activity and found that 23 (22%) tumors were telomerase negativ e. Careful histological confirmation of an adjacent cryosection and/or microdissection of pure tumor cells reduced this number to 5 (5%), Th us, truly telomerase-negative invasive breast cancers are rare, making this enzyme a potentially very useful tumor marker in breast cancer.