Gene Finding Will Help Doctors Predict Prostate Cancer Risk
Researchers report that a variation in a portion of DNA strongly predicts prostate cancer risk, according to a study in Nature Genetics.
In addition, this common variation may be responsible for up to 20 percent of prostate cancer cases in Caucasian men in the US.
DNA is short for deoxyribonucleic acid, which is the genetic material determining the makeup of all living cells.
The research was conducted by investigators from the National Cancer Institute (NCI) and partners in the Cancer Genetic Markers of Susceptibility (CGEMS) initiative.
Prostate cancer is the third leading cause of cancer-related death in men, yet very little is known about its origins, scientists say.
In 2007 in the US, there will be an estimated 219,000 new prostate cancer cases and an estimated 27,000 deaths.
CGEMS researchers are scanning the entire human genome to identify common, inherited gene mutations that increase the risks for breast and prostate cancers.
"Discovery of this common variation is very exciting," says Dr. John E. Niederhuber, director of the NCI.
"Building on this finding we may be able to identify men at highest risk for prostate cancer, diagnose the disease earlier, and hopefully prevent it all together," says Dr. Niederhuber.
"One of the next steps is to understand the mechanism by which this genetic variation exerts its effect on cancer risk," he notes.
This gene variation was discovered on chromosome 8.
Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 8, one inherited from each parent, form one of the pairs.
Chromosome 8 spans about 146 million base pairs (the chemicals that comprise DNA), represents about 5 percent of the total DNA in cells, and contains an estimated 700 to 1,100 genes.
“We now have two significant regions in the same general area that convey risk for prostate cancer, says Dr. Meredith Yeager, lead author on the study.
One location under study could be responsible for about seven percent of prostate cancer cases in Caucasian men of northern European descent.
The two genetic regions together could account for as much as one quarter of prostate cancer cases in Caucasian men.
“CGEMS allows us to look systematically across the entire human genome and search for common genetic variations that confer risk for prostate cancer, a very common and very complex disease,” says Dr. Stephen Chanock, director of the NCI Core Genotyping Facility in the Advanced Technology Center.
Dr. Gilles Thomas, a lead scientist at CGEMS, says that identification of new regions furthers efforts to uncover the genetic basis of prostate cancer, which may eventually lead to more insights into cancer causes in general.
Currently, scientists are collecting similar data on breast cancer, the second leading cause of cancer-related deaths in women in the US.
The CGEMS database will soon contain close to 2.5 billion genotypes, allowing researchers to identify genetic risk factors for breast and prostate cancers.
By comprehensively surveying for common genetic variations and following-up on promising findings, researchers hope to identify and verify associations that increase or decrease the risk of these cancers.
Always consult your physician for more information.
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The fear of having prostate cancer can be devastating to men.
However, it is most successfully treated when found early.
According to the American Cancer Society, 91 percent of all prostate cancers are discovered while they are either localized (confined to the prostate) or regional (nearby).
The five-year survival rate for men diagnosed with prostate tumors discovered at these stages is 99 percent.
In the past 20 years, the five-year survival rate for all stages combined has increased from 67 percent to 99 percent.
Prostate cancer is the most common cancer among men, excluding skin cancer.
There are usually no specific signs or symptoms of early prostate cancer - which is why prostate screening is so important.
An annual physical examination, prostate-specific antigen (PSA) blood test, and digital rectal exam (DRE) provide the best chance of identifying prostate cancer in its earliest stages.
The following are the most common symptoms of prostate cancer:
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weak or interrupted flow of urine
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urinating often (especially at night)
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difficulty urinating or holding back urine
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inability to urinate
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pain or burning when urinating
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blood in the urine or semen
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nagging pain in the back, hips, or pelvis
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difficulty having an erection
The symptoms of prostate cancer may resemble other conditions or medical problems.
As a man gets older, his prostate may grow bigger and obstruct the flow of urine, or interfere with sexual function.
An enlarged prostate gland - a condition called benign prostate hyperplasia - may require treatment with medicine or surgery to relieve symptoms.
This common benign prostate condition, which is not cancer, can cause many of the same symptoms as prostate cancer.
Always consult your physician for more information.
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