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Discussion Boardp53 and tumor block was posted 05/20/2001 05:20 pm by peter argani
E-mail Address: firstname.lastname@example.org
Hi Elizabeth: As usual, you are asking very good questions. I will try to
answer them in order.
1. It is not uncommon for bile duct tumors to be small and have a low
percentage of tumor cells within them. They tend to be small when they are
located distally and block the bile duct early; this results in symptoms of
jaundice which brings people to the doctor. The prognosis is generally
better when the tumor is smaller. Like pancreas cancer, bile duct carcinomas
are almost always associated with a large reactive scar around them (also
known as desmoplastic reaction). The scar tissue itself is benign, and it is
a reaction to the bile duct cancer cells. Therefore, in a bile duct tumor
mass, the majority of the cells that make up the mass may be benign
fibroblasts that make up the benign scar. There still are cancer cells in
the mass; they just are outnumbered.
2 and 3. The immunohistochemical stain for p53 tells us how many of the
tumor cells express detectable p53 protein. The noncancer cells are not
included in this result. In general, p53 is not detectable by
immunohistochemistry in normal bile duct epithelium or any other normal
tissue. p53 protein expression by immunohistochemistry is an imperfect but
still valuable test that correlates with p53 gene mutation. Usually, mutated
p53 protein persists longer in the cell than normal p53, and hence it becomes
detected by immunohistochemistry. Tumors in which a high percentage of the
tumor cells overexpress p53 protein (>30%) are very likely to have p53
mutations in them, while those that express little p53 protein (<10% of
cells) are unlikely to have p53 mutations. It is hard to predict if p53 is
mutated in tumors that are express p53 in 10-30% of cells.
I hope this is helpful.
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