Tumor growth in the brain
Question: We have information on tumor growth that says 20% of the cell grows at one time which has the tumor in it. Therefore 80% dies. The doubling time is 7 days, but is the 7 days for the whole tumor or the 20%? For Example: You have 100 cells of the tumor. If 20% live, then will the doubling be for the 20 cells or the 100 cells? Our information also says that cell replication takes 2-5 days. Do you have any suggestions on how we can make this into a equation?

Answer: 20% growth doesn't mean 80% necessarily. Cells have the ability to rest without dying. This is the complicating factor. Take the total, subtract the deaths, add in a factor for return of the "resting" cells, and put in an exponential factor. It should be close anyway.

Carcinoid-like tumors
Question: My mother has had surgery for carcinoid-like tumors, and we would like information regarding such. What are they, what causes them, what is the prescribed treatment, do they recur, do they metastasize?

Answer: Carcinoid tumors usually occur in the GI tract. Although one of the more common tumors of the GI tract, they are fairly infrequent. The cause is not clear, although one variety tends to have a familial or genetic predisposition. They often secrete substances that produce different types of symptoms and are often the way that they are detected, especially if small. They tend to be slow growing and only rarely malignant. However, they can reoccur and produce problems by the size and position of the tumor. Recurrent surgery is occasionally necessary. Recently, a drug called octreotide has been used to suppress some of the symptoms of carcinoid secreting tumors. Since a subgroup of these tumors occurs in families, you should inform your physician that your mother has a carcinoid. This group is called MEN Type one. He/she should be familiar with this syndrome.

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