Scans show effectiveness of medullary thyroid cancer treatment, experts say

Researchers have reported using positron emission tomography (PET) scans to determine the effectiveness of a new prescription treatment for medullary thyroid cancer.

A study published in the Journal of Nuclear Medicine found that vandetanib, a protein kinase inhibitor (PKIs), appears to slow the metabolic rate of cancer cells in the thyroid.

Its authors say that the paper's results are two-pronged. First, vandetanib appears to be effective in reducing the rate of multiplication of thyroid cancer cells. Second, the method used to make this determination - PET scanning - may be a more effective way to evaluate patient response to PKIs.

Protein kinases are molecules that act as cellular switches, determining how much energy a cell uses as its organelles operate and as it replicates. Mutations in the DNA that regulate protein kinases can leave them stuck in what amounts to the "on position," allowing cells to grow without limit.

This process often gives rise to cancer, researchers said. PKIs like vandetanib inhibit medullary cancer by blocking the action of overactive protein kinases.

However, prior to the study many endocrinologists had few ways to track the reaction to PKIs beyond measuring the size of the tumors themselves.

The study's authors used PET scans to examine medullary thyroid cancer growth, and they tried it in three different ways, all of which were deemed successful.

Researchers first cultured the cancer cells in a dish, dosed them with vandetanib and used PET to examine the cells' metabolism. The scans, which visualize cell energy by passing gamma rays through them, showed that the drug lowered the metabolism of medullary thyroid cancer.

They then tried the same technique using laboratory rodents and later a human participant, both with similarly positive results.

Between 2 and 3 percent of all cases of thyroid cancer are medullary carcinomas, according to the National Cancer Institute.