U.S. cancer scientists say they've demonstrated a gene involved in regulating aging also blocks prostate cancer cell growth.
Dr. Richard Pestell and colleagues at the Kimmel Cancer Center at Thomas Jefferson University say they hope the newly found connection will aid in better understanding the development of prostate cancer and lead to new drugs against the disease.
The gene, SIRT1, is a member of a family of enzymes called sirtuins that have far-reaching influence in all organisms, including roles in metabolism, gene expression and aging.
"We know that sirtuins play a role in aging, and that the risk for prostate cancer increases with aging, but no one has ever linked the two until now," said Pestell, professor and chairman of cancer biology at Jefferson Medical College. "We've shown that by making a prostate cancer with cells overexpressing a mutation for the androgen receptor, which is resistant to current forms of therapy, we can almost completely block the growth of these cells with SIRT1."
The study is reported in the journal Molecular and Cellular Biology.
Tuesday, November 28, 2006
Prostate cancer screenings in men 70 and older
THE QUESTION: Are doctors doing unnecessary screening for prostate cancer in men 70 and older?
THE CONTEXT: For men with a life expectancy of less than 10 years, the risks associated with screening for prostate cancer outweigh the benefits. But some reports have suggested that many sick, elderly men are being screened.
THE STUDY: Researchers studied the records of nearly 600,000 men age 70 and older who were treated by the Department of Veterans Affairs (VA) in 2002 and 2003. They analyzed their health status and whether or not they were given prostate-specific antigen screening, also known as PSA screening.
THE RESULTS: In all, 56 percent of the men received PSA screening. The percentage of men who were screened declined with age. But within each age group, men who had lower life-expectancy - and therefore stood to benefit less from screening - were screened roughly as often as healthier men with a higher life expectancy.
Among men 85 and older, fewer than 10 percent have a life expectancy of 10 years or more. Nevertheless, roughly one-third were screened -- a figure that held constant for the healthiest and sickest subgroups.
The authors concluded that screening rates among men with low life expectancies should be "much lower than the current practice.''
The abstract of the study, which was published in the Journal of the American Medical Association, is available online at jama.ama-assn.org.
THE CONTEXT: For men with a life expectancy of less than 10 years, the risks associated with screening for prostate cancer outweigh the benefits. But some reports have suggested that many sick, elderly men are being screened.
THE STUDY: Researchers studied the records of nearly 600,000 men age 70 and older who were treated by the Department of Veterans Affairs (VA) in 2002 and 2003. They analyzed their health status and whether or not they were given prostate-specific antigen screening, also known as PSA screening.
THE RESULTS: In all, 56 percent of the men received PSA screening. The percentage of men who were screened declined with age. But within each age group, men who had lower life-expectancy - and therefore stood to benefit less from screening - were screened roughly as often as healthier men with a higher life expectancy.
Among men 85 and older, fewer than 10 percent have a life expectancy of 10 years or more. Nevertheless, roughly one-third were screened -- a figure that held constant for the healthiest and sickest subgroups.
The authors concluded that screening rates among men with low life expectancies should be "much lower than the current practice.''
The abstract of the study, which was published in the Journal of the American Medical Association, is available online at jama.ama-assn.org.
Monday, November 20, 2006
Prostate Cancer and Association With Plasma Cholesterol
Prostate cancer patients who had lower levels of cholesterol in their blood had a significantly reduced chance of developing more aggressive forms of the disease, compared to patients with higher cholesterol readings.
These findings may help explain the earlier discovery, reported by the same team of researchers at the AACR annual meeting in 2005, that men who used statin drugs experienced half the risk of developing advanced prostate cancer.
"Statin drugs reduce cholesterol in the blood, but they also influence a number of different pathways," said the study's lead researcher, Elizabeth Platz, ScD, MPH, an associate professor in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health. "This study suggests that the ability of statins to lower cholesterol may be important to prostate carcinogenesis, but we are continuing to examine other pathways with which statin drugs interact, such as reduction of inflammation."
The researchers looked at cholesterol levels first because cholesterol affects cell signaling and survival. Some scientists theorize that a large quantity of cholesterol in the blood could stimulate the survival of abnormal prostate cells.
They studied blood drawn from 698 men before they were diagnosed with prostate cancer and matched it to blood taken from 698 men who had not been diagnosed with the disease. All of the men participated in Harvard University's Health Professionals Follow-up Study, a group of 18,018 participants who provided a blood sample between 1993 and 1995.
They found that mean cholesterol levels did not differ between the men with prostate cancer and the control participants, suggesting that cholesterol was not involved in the initial development of prostate cancer, Platz said.
But when comparing men who had the lowest quartile of serum cholesterol to men who had the highest, they found that prostate cancer patients with lower cholesterol had the lowest risk of developing a more worrisome form of the disease. They specifically found that the risk of being diagnosed with high-grade or advanced cancer was reduced by 40 percent and 50 percent, respectively.
Platz says it is not clear at what levels serum cholesterol may stimulate the abnormal growth seen in cancer development. "The findings suggest either that high cholesterol may push existing prostate cancer to become aggressive, or, alternatively, very low levels of cholesterol may provide protection against development of an aggressive cancer," she said. "We just don't know which it is at this point."
She also said that because the findings come from an observational study, not a trial, it is impossible to conclude that men can lower their risk of developing an aggressive form of prostate cancer by reducing their intake of saturated fat, the type of fat that increases serum cholesterol, which some studies have linked to an increased risk of advanced prostate cancer.
"It is too soon to say that such measures would be specifically beneficial to lowering such a risk, but for good health in general, it is prudent to consume a diet that contains healthful fats that do not increase serum cholesterol," she said.
These findings may help explain the earlier discovery, reported by the same team of researchers at the AACR annual meeting in 2005, that men who used statin drugs experienced half the risk of developing advanced prostate cancer.
"Statin drugs reduce cholesterol in the blood, but they also influence a number of different pathways," said the study's lead researcher, Elizabeth Platz, ScD, MPH, an associate professor in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health. "This study suggests that the ability of statins to lower cholesterol may be important to prostate carcinogenesis, but we are continuing to examine other pathways with which statin drugs interact, such as reduction of inflammation."
The researchers looked at cholesterol levels first because cholesterol affects cell signaling and survival. Some scientists theorize that a large quantity of cholesterol in the blood could stimulate the survival of abnormal prostate cells.
They studied blood drawn from 698 men before they were diagnosed with prostate cancer and matched it to blood taken from 698 men who had not been diagnosed with the disease. All of the men participated in Harvard University's Health Professionals Follow-up Study, a group of 18,018 participants who provided a blood sample between 1993 and 1995.
They found that mean cholesterol levels did not differ between the men with prostate cancer and the control participants, suggesting that cholesterol was not involved in the initial development of prostate cancer, Platz said.
But when comparing men who had the lowest quartile of serum cholesterol to men who had the highest, they found that prostate cancer patients with lower cholesterol had the lowest risk of developing a more worrisome form of the disease. They specifically found that the risk of being diagnosed with high-grade or advanced cancer was reduced by 40 percent and 50 percent, respectively.
Platz says it is not clear at what levels serum cholesterol may stimulate the abnormal growth seen in cancer development. "The findings suggest either that high cholesterol may push existing prostate cancer to become aggressive, or, alternatively, very low levels of cholesterol may provide protection against development of an aggressive cancer," she said. "We just don't know which it is at this point."
She also said that because the findings come from an observational study, not a trial, it is impossible to conclude that men can lower their risk of developing an aggressive form of prostate cancer by reducing their intake of saturated fat, the type of fat that increases serum cholesterol, which some studies have linked to an increased risk of advanced prostate cancer.
"It is too soon to say that such measures would be specifically beneficial to lowering such a risk, but for good health in general, it is prudent to consume a diet that contains healthful fats that do not increase serum cholesterol," she said.
Monday, November 13, 2006
Proteins to Treat Prostate Cancer!
Here is good news for the patients with prostate cancer. According to a new study, researchers have come out with a new type of therapy that would be very effective in treating prostate cancer.
Earlier tests conducted on mice have proved that this new therapy called, PRX302 is capable of killing the cancerous prostate cells without destroying or harming the healthy cells. Therapy PRX302 uses a protein for treating prostate cancer and the interesting thing about this protein is that it is produced by the cancerous cells themselves.
So, it would not be wrong saying that now doctors will use protein made of cancer cells to treat the deadly cancer.
Earlier tests conducted on mice have proved that this new therapy called, PRX302 is capable of killing the cancerous prostate cells without destroying or harming the healthy cells. Therapy PRX302 uses a protein for treating prostate cancer and the interesting thing about this protein is that it is produced by the cancerous cells themselves.
So, it would not be wrong saying that now doctors will use protein made of cancer cells to treat the deadly cancer.
Tuesday, November 07, 2006
Prostate Cancer Risk Factors
A risk factor is anything that may increase a person’s chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases, including cancers, have different risk factors. In general, all men are at risk for prostate cancer. However, there are specific risk factors that increase the likelihood that certain men will develop the disease, including the following:
Age is a risk factor for prostate cancer, especially men age 50 and older. More than 80 percent of all prostate cancers are diagnosed in men over the age of 65. Race: Prostate cancer is nearly twice as common among African-American men than it is among Caucasian-American men. Japanese and Chinese men native to their country have the lowest rates of prostate cancer.
Diet: Data suggests that the diet consumed in Western industrialized countries may be one of the most important contributory factors for developing prostate cancer. The following information regarding diet and its effect on the risk for prostate cancer include men who eat a high-fat diet may have a greater chance of developing prostate cancer. Dietary fiber intake may decrease the progression of prostate cancer. Soy protein lowers fat intake, and the isoflavones in soy have been found to inhibit the growth of prostate cancer. Vitamin E and selenium Vitamin E, an antioxidant, combined with selenium, has been shown to inhibit tumor growth in laboratory animals. Carotenoids Carotenoids containing lycopenes have been shown to inhibit the growth of human prostate cancer cells in tissue cultures. The primary source of lycopenes is processed tomatoes in tomato juice and tomato paste. Obesity Obesity not only contributes to diabetes and high cholesterol, but has also been associated with some common cancers including prostate cancer.
Vasectomy, BPH (benign prostatic hyperplasia), or STD (sexually transmitted disease) Researchers have looked at whether men who have had a vasectomy, BPH, or those who have had exposure to STD’s are at increased risk for prostate cancer. Some studies suggest a link, while others don’t. Family history of prostate cancer. A father or brother with prostate cancer doubles a man’s risk of developing prostate cancer. The risk is even higher for men with several affected relatives. Geneticists divide families into three groups, depending upon the number of men with prostate cancer and their ages of onset, including the following: Sporadic - a family with prostate cancer present in one man, at a typical age of onset. Familial - a family with prostate cancer present in more than one person, but with no definitive pattern of inheritance and usually an older age of onset. Hereditary - Five to 10 percent of prostate cancer cases are considered hereditary. Genetic Approximately 9 percent of all prostate cancers and 45 percent of cases in men younger than age 55 can be attributed to a cancer susceptibility gene that is inherited as a dominant trait (from parent to child).
Age is a risk factor for prostate cancer, especially men age 50 and older. More than 80 percent of all prostate cancers are diagnosed in men over the age of 65. Race: Prostate cancer is nearly twice as common among African-American men than it is among Caucasian-American men. Japanese and Chinese men native to their country have the lowest rates of prostate cancer.
Diet: Data suggests that the diet consumed in Western industrialized countries may be one of the most important contributory factors for developing prostate cancer. The following information regarding diet and its effect on the risk for prostate cancer include men who eat a high-fat diet may have a greater chance of developing prostate cancer. Dietary fiber intake may decrease the progression of prostate cancer. Soy protein lowers fat intake, and the isoflavones in soy have been found to inhibit the growth of prostate cancer. Vitamin E and selenium Vitamin E, an antioxidant, combined with selenium, has been shown to inhibit tumor growth in laboratory animals. Carotenoids Carotenoids containing lycopenes have been shown to inhibit the growth of human prostate cancer cells in tissue cultures. The primary source of lycopenes is processed tomatoes in tomato juice and tomato paste. Obesity Obesity not only contributes to diabetes and high cholesterol, but has also been associated with some common cancers including prostate cancer.
Vasectomy, BPH (benign prostatic hyperplasia), or STD (sexually transmitted disease) Researchers have looked at whether men who have had a vasectomy, BPH, or those who have had exposure to STD’s are at increased risk for prostate cancer. Some studies suggest a link, while others don’t. Family history of prostate cancer. A father or brother with prostate cancer doubles a man’s risk of developing prostate cancer. The risk is even higher for men with several affected relatives. Geneticists divide families into three groups, depending upon the number of men with prostate cancer and their ages of onset, including the following: Sporadic - a family with prostate cancer present in one man, at a typical age of onset. Familial - a family with prostate cancer present in more than one person, but with no definitive pattern of inheritance and usually an older age of onset. Hereditary - Five to 10 percent of prostate cancer cases are considered hereditary. Genetic Approximately 9 percent of all prostate cancers and 45 percent of cases in men younger than age 55 can be attributed to a cancer susceptibility gene that is inherited as a dominant trait (from parent to child).
Monday, November 06, 2006
Study urges earlier prostate exams
The dubious rite of passage when a man turns 50 might arrive even earlier, based on a study that suggests screening for prostate cancer should begin at 40.
Men are advised to get a yearly screening based on the amount of the prostate hormone PSA found in their blood. A high level is a warning sign of prostate cancer.
Now, a team of Johns Hopkins researchers says screening should begin about age 40 but be done less frequently. The team also recommends basing a diagnosis on multiple readings over time that would show how a man's PSA level changes.
Those changes, the researchers say, would reduce the number of men treated unnecessarily and would better identify potentially deadly tumors that require aggressive treatment.
Their findings, published Wednesday in the Journal of the National Cancer Institute, were based on their study of nearly 1,000 men who volunteered for a long-term study of aging that began in 1958.
Using frozen blood samples, the Hopkins researchers explored whether the speed at which a man's PSA levels changed was a good predictor of his chances of dying of prostate cancer.
Current PSA tests, the researchers said, look at the concentration of the hormone in a man's blood at one point. If the man has a high PSA level, the next step is a biopsy to determine whether he has a cancerous prostate tumor.
Researchers found that the faster a man's PSA level increased, the more likely he was to die of prostate cancer, said Dr. H. Ballentine Carter, a professor of urology and oncology at the Johns Hopkins University School of Medicine and the study's lead author.
''We don't need to diagnose more prostate cancer,'' he said. ''We need to find the prostate cancers that are fatal.''
The current method of looking at a single reading of a man's PSA level proved less effective.
In many cases, Carter said, a man's PSA level increased rapidly before it reached a concentration so high that it would prompt a doctor to order a biopsy. The PSA rise in men who eventually died of prostate cancer sometimes began before age 50. Using the rate of increase -- a measure called PSA velocity -- would have provided an earlier alert, he said.
Carter said that method also would reduce the number of men who undergo treatment for tumors that diminish neither their quality of life nor length of life.
Dr. Mark S. Litwin, who had not seen the Hopkins study, questioned the wisdom of PSA testing for men younger than 50.
Prostate cancer cases are rare in men in their 40s, said Litwin, a professor of urology and oncology at the University of California-Los Angeles. He argued that earlier testing should be reserved for high-risk patients, such as blacks and people with family histories of prostate cancer.
He did agree that looking at the speed at which a man's PSA level changed is a good tool.
''It sounds like it's certainly consistent with prior research,'' he said of the Hopkins study.
This year, the American Cancer Society estimates, more than 234,000 American men will be diagnosed with prostate cancer and 27,000 will die from it.
Men are advised to get a yearly screening based on the amount of the prostate hormone PSA found in their blood. A high level is a warning sign of prostate cancer.
Now, a team of Johns Hopkins researchers says screening should begin about age 40 but be done less frequently. The team also recommends basing a diagnosis on multiple readings over time that would show how a man's PSA level changes.
Those changes, the researchers say, would reduce the number of men treated unnecessarily and would better identify potentially deadly tumors that require aggressive treatment.
Their findings, published Wednesday in the Journal of the National Cancer Institute, were based on their study of nearly 1,000 men who volunteered for a long-term study of aging that began in 1958.
Using frozen blood samples, the Hopkins researchers explored whether the speed at which a man's PSA levels changed was a good predictor of his chances of dying of prostate cancer.
Current PSA tests, the researchers said, look at the concentration of the hormone in a man's blood at one point. If the man has a high PSA level, the next step is a biopsy to determine whether he has a cancerous prostate tumor.
Researchers found that the faster a man's PSA level increased, the more likely he was to die of prostate cancer, said Dr. H. Ballentine Carter, a professor of urology and oncology at the Johns Hopkins University School of Medicine and the study's lead author.
''We don't need to diagnose more prostate cancer,'' he said. ''We need to find the prostate cancers that are fatal.''
The current method of looking at a single reading of a man's PSA level proved less effective.
In many cases, Carter said, a man's PSA level increased rapidly before it reached a concentration so high that it would prompt a doctor to order a biopsy. The PSA rise in men who eventually died of prostate cancer sometimes began before age 50. Using the rate of increase -- a measure called PSA velocity -- would have provided an earlier alert, he said.
Carter said that method also would reduce the number of men who undergo treatment for tumors that diminish neither their quality of life nor length of life.
Dr. Mark S. Litwin, who had not seen the Hopkins study, questioned the wisdom of PSA testing for men younger than 50.
Prostate cancer cases are rare in men in their 40s, said Litwin, a professor of urology and oncology at the University of California-Los Angeles. He argued that earlier testing should be reserved for high-risk patients, such as blacks and people with family histories of prostate cancer.
He did agree that looking at the speed at which a man's PSA level changed is a good tool.
''It sounds like it's certainly consistent with prior research,'' he said of the Hopkins study.
This year, the American Cancer Society estimates, more than 234,000 American men will be diagnosed with prostate cancer and 27,000 will die from it.
Sunday, November 05, 2006
Newer Approach Urged In Screening For Aggressive Prostate Cancer
Researchers at the Johns Hopkins University School of Medicine say that how fast the amount of PSA (prostate-specific antigen) in a man's blood increases, or PSA velocity (PSAV), is an accurate gauge of tumor aggression and danger, even when PSA levels are so low as to not warrant a biopsy.
Findings of a Hopkins study of PSAV, in this month's Journal of the National Cancer Institute, may add a new level of predictive accuracy to prostate cancer testing, the value of which has remained controversial under currently accepted guidelines, the investigators say.
"Our data provide a further argument for PSA testing that begins relatively early in life, when PSA levels are usually lower and prostate enlargement is not a confounding factor in diagnosis," says H. Ballentine Carter, M.D., the director of the Johns Hopkins Division of Adult Urology at the Brady Urological Institute and lead author of the study. "We would recommend that men at around age 40, not 50, have their PSA checked to develop a baseline against which to compare future changes (velocity), since even a slight rise in PSA may indicate a potential for cancer down the road."
An estimated 234,460 men in the United States will be diagnosed with prostate cancer this year, according to the American Cancer Society.
"The main debate over how to use PSA has centered on the choice of the level that is used to trigger a biopsy," says Carter, a professor at the Johns Hopkins University School of Medicine. "Lowering the level that triggers a biopsy leads to detection of more harmless cancers, and higher levels could miss the opportunity to detect an important cancer early. We have found that the rate at which a man's PSA rises may be more important than any absolute level for identifying men who will develop life-threatening cancer while their disease is still curable. In addition, PSA velocity could be a useful method for identifying those men with a prostate cancer that could be safely monitored - an approach termed 'active surveillance'."
PSA is a protein found in the bloodstream of men, produced by the prostate gland and found at increased levels in those with prostate cancer. In previous research, PSA velocity in the year before prostate cancer diagnosis has been shown to identify men who are likely not to be cured by surgery. However, Carter's latest findings show that PSA velocity can also identify men with life-threatening disease at a time when it is still curable.
Using serum samples dating as far back as 1958, frozen as part of an ongoing randomized health study of men, Carter and his team determined PSA velocity in 980 of those study participants (856 without prostate cancer, 104 with the disease and 20 who died from it) up until May of 2005. They found that the PSA velocity determined at a time when PSA levels would not have triggered a biopsy were predictive of death from prostate cancer 20 to 30 years later.
Those men whose PSA velocity was lower had a 92 percent chance of not dying of prostate cancer 25 years later; whereas those with a higher PSA velocity had a 54 percent chance of not dying of prostate cancer. The rates of prostate cancer death were 1,240 in 100,000 for subjects with a higher velocity compared to 140 in 100,000 for those with lower velocities.
Carter emphasizes that an important difference between the current research and previous studies is that the subjects in the current study were not selected, but rather taken at random from a large, ongoing study, thus more accurately representing the U.S. population.
Findings of a Hopkins study of PSAV, in this month's Journal of the National Cancer Institute, may add a new level of predictive accuracy to prostate cancer testing, the value of which has remained controversial under currently accepted guidelines, the investigators say.
"Our data provide a further argument for PSA testing that begins relatively early in life, when PSA levels are usually lower and prostate enlargement is not a confounding factor in diagnosis," says H. Ballentine Carter, M.D., the director of the Johns Hopkins Division of Adult Urology at the Brady Urological Institute and lead author of the study. "We would recommend that men at around age 40, not 50, have their PSA checked to develop a baseline against which to compare future changes (velocity), since even a slight rise in PSA may indicate a potential for cancer down the road."
An estimated 234,460 men in the United States will be diagnosed with prostate cancer this year, according to the American Cancer Society.
"The main debate over how to use PSA has centered on the choice of the level that is used to trigger a biopsy," says Carter, a professor at the Johns Hopkins University School of Medicine. "Lowering the level that triggers a biopsy leads to detection of more harmless cancers, and higher levels could miss the opportunity to detect an important cancer early. We have found that the rate at which a man's PSA rises may be more important than any absolute level for identifying men who will develop life-threatening cancer while their disease is still curable. In addition, PSA velocity could be a useful method for identifying those men with a prostate cancer that could be safely monitored - an approach termed 'active surveillance'."
PSA is a protein found in the bloodstream of men, produced by the prostate gland and found at increased levels in those with prostate cancer. In previous research, PSA velocity in the year before prostate cancer diagnosis has been shown to identify men who are likely not to be cured by surgery. However, Carter's latest findings show that PSA velocity can also identify men with life-threatening disease at a time when it is still curable.
Using serum samples dating as far back as 1958, frozen as part of an ongoing randomized health study of men, Carter and his team determined PSA velocity in 980 of those study participants (856 without prostate cancer, 104 with the disease and 20 who died from it) up until May of 2005. They found that the PSA velocity determined at a time when PSA levels would not have triggered a biopsy were predictive of death from prostate cancer 20 to 30 years later.
Those men whose PSA velocity was lower had a 92 percent chance of not dying of prostate cancer 25 years later; whereas those with a higher PSA velocity had a 54 percent chance of not dying of prostate cancer. The rates of prostate cancer death were 1,240 in 100,000 for subjects with a higher velocity compared to 140 in 100,000 for those with lower velocities.
Carter emphasizes that an important difference between the current research and previous studies is that the subjects in the current study were not selected, but rather taken at random from a large, ongoing study, thus more accurately representing the U.S. population.
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