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WHO will be asked to complete
the survey? WHAT will the survey
ask? WHERE will I get the
survey? WHEN can I expect my
survey to arrive? WHY does PROGRESS need
to ask more questions? | |||
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| In the PROGRESS
follow-up survey, you will notice that we ask about more cancer sites
than just the prostate. A large portion of the survey asks about types
of cancer diagnosed in your close relatives (parents, children, brothers
and sisters). You may wonder why a prostate cancer study would be interested
in other cancers. When PROGRESS began in 1995, scientists expected hereditary prostate cancer research to follow a similar path as that of hereditary breast cancer. In 1994, breast cancer researchers discovered two genes, called BRCA1 and BRCA2, which cause breast cancer in the people who inherit changed or damaged copies of those genes. The BRCA genes are highly penetrant. This means if a person inherits a damaged BRCA1 or BRCA2 gene, it is very likely that the person will develop breast cancer. Statistical models predicted a similar type of gene may exist for prostate cancer. Instead, the past seven years have revealed a different story for prostate cancer genetics. Most scientists now believe there are perhaps a dozen or so genes that cause inherited prostate cancer. In addition to involving more genes, hereditary prostate cancer may also differ from breast cancer in several other important ways. The genes may be less penetrant – meaning that if a person inherits an altered copy of the gene, the chances of developing cancer are not as high. Also, two or more genes may work together, so that both genes must have been altered in order for cancer to occur (called a gene-gene interaction). Or perhaps the person with a damaged or variant gene may need to have some other factors, such as a certain diet or other environmental exposures, in order to get cancer (called a gene-environment interaction). The genetic picture for prostate cancer is much more complicated than was first thought. In response to the changing ideas about hereditary prostate cancer, the scientists here at PROGRESS are working on new ways to find the genes. Our primary goal at the beginning of the study was to conduct a genome scan, expecting that it would highlight the areas of DNA that may contain inherited genes. A genome scan is a process of looking at the DNA in all the chromosomes at regular intervals to see if there are differences that occur in men with prostate cancer but not in men without the disease. But if there are twelve or more prostate cancer genes, it will be much harder to see a clear pattern emerge. It may help clear up the pattern if we can group together families who are alike in some interesting ways. This approach is what led us to the location of a possible gene called CAPB in 1997, which appears to be important in some PROGRESS families with both prostate cancer and brain cancer. As of June 2002, we are finished with the full genome scan in all the PROGRESS families and analyses are underway. It is too early to know if there will be major findings from the full group of families. With so much information in so many different families, in order to get a clear "signal" from these data it may be helpful to be able to identify smaller groups of families who share certain characteristics. When identifying similar families to create groups, we are limited by the information we collected in the first questionnaire. We asked some questions about other types of cancer in the family, but we did not ask which relative had the cancer and how old the relative was when he or she was diagnosed. We now know that these details could make a big difference in how we group families and ultimately may help to identify the genes that cause prostate cancer in families. |
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