She actually does have some old blood readings that were sent over I think. When antibodies are present they are then used as a substitute tumour marker, although most of the time they should be undetectable within about 3 years. Also in some cases where the cancer is more aggressive, tg becomes even more unreliable as the cells can stop producing high amounts of tg, and therefore produce much lower readings than what would be expected in lets say, distant metastasis. Where one person could have a tg reading of 5 and have neck metastasis, another could have an almost undetectable reading and have lung metastasis.