PSA Test
PSA Test a Thing of the Past? MONDAY, May 10 (HealthDayNews) — The PSA test, long the gold standard for deciding who should have a biopsy for prostate cancer, may have outlived its usefulness for the most part.
Stanford University researchers say PSA (prostate specific antigen) levels bear little relationship to the severity of a cancer these days. They presented their finding May 9 at the American Urology Association’s annual meeting in San Francisco.
“”We need to recognize that PSA is no longer a marker for prostate cancer,”" said study author Dr. Thomas A. Stamey, a professor of urology at Stanford University School of Medicine. “”We urgently need to find a new marker for prostate cancer, and that marker must be proportional to how much cancer you have.”"
“”We have been so thorough and effective in screening for prostate cancer over this 20-year period that PSA no longer has a relationship to prostate cancer,”" Stamey said. “”Because we all develop the cancer, we’re now removing prostates from men whose cancer is so small that they do not need the procedure. We’re finding all these little cancers that are never going to be a danger to the patient.”"
“”In smaller cancers, the PSA test is not relevant anymore,”" Stamey explained. “”You might as well biopsy a man because he has blue eyes.”"
PSA is a protein produced by the cells of the prostate gland. Because blood levels of the antigen tend to rise as the gland enlarges, it has been used for years as a test of whether a person needs a biopsy for cancer. The test, however, is not foolproof.
“”People’s perceptions [are] that if your PSA is a certain level, you’re very likely or you do have prostate cancer, and that is incorrect,”" said Dr. Mark Soloway, chairman of the department of urology at the University of Miami School of Medicine.
“”The PSA test is a very good test. It’s not a perfect test, especially in younger men,”" added Dr. Jay Brooks, chief of hematology/oncology at the Ochsner Clinic Foundation in New Orleans.
To see how the efficacy of the PSA test might have waned, researchers in Stamey’s lab reexamined every prostate that had been removed since 1983 (1,317 of them) and compared the size of the cancer with blood PSA levels. None of the cancers had been treated with chemotherapy, radiation, or hormones before surgery.
Each cancer was rated on eight or 10 different parameters thought to indicate how aggressive the cancer was, including the size of the tumor and its grade.
Stamey then divided the samples into four five-year periods to see what had happened to the qualities of the cancers over time.
“”What we showed was that in the first five years, the cancers were related to the level of serum PSA,”" Stamey said. “”Then in the next five years, they were still bad but not as bad as the first five years. Then in the third five-year period, they were better and better. And in the last five years ending Jan. 1 of this year, the cancers were so small they had no relationship to serum PSA.”"
Twenty years ago, 80 percent of cancers were detected by digital rectal examination; only 20 percent of cancers are now detected that way, Stamey explained.
Instead, PSA levels today are driven by benign enlargement of the prostate, a condition that does not usually require surgery.
The concept that the PSA test is not foolproof is not an entirely new one. “”The point is well taken that in microscopic disease, the volume of cancer is clearly overshadowed by the volume of noncancer, so that the cancer cannot be the cause of the elevated PSA,”" said Dr. John Phillips, physician-in-charge of urologic oncology at Beth Israel Medical Center in New York City.
The question now is what can replace it. “”People are trying to find other ways of finding cancer,”" Phillips added.
As a matter of fact, University of Pittsburgh researchers who presented at the same conference reported that additional testing for a protein called early prostate cancer antigen (EPCA) might mean prostate cancer could be detected as many as five years earlier than with just the PSA test.
“”We would like a perfect test that would only find biologically significant cancers,”" Soloway said. “”Today we can’t distinguish between those with indolent cancer and those whose cancers threaten their life. We need another way. That’s going to be a difficult task.”"
In the meantime, the American Urological Association issued a statement that, for the time being, the PSA test in combination with a digital rectal exam and a full medical history is the best way to determine when a biopsy might be necessary
Vitamin D More Essential for Bone Health Than Calcium
Vitamin D More Important Than Calcium For bone Health November 9, 2005 Consuming more than 800 mg of calcium per day may be unnecessary for bone health if the body has enough vitamin D, say Icelandic researchers.
Using food consumption records from more than 900 adults, the researchers determined that sufficient vitamin D levels can ensure an ideal level of parathyroid hormone (PTH) – a measure of calcium metabolism – even when calcium intake is less than 800 mg per day. But consuming more than 1200 mg of calcium daily is not enough to maintain ideal PTH if the vitamin D status is insufficient. The study is part of a growing body of work that points to the important role of vitamin D, and not just calcium alone, in bone health. Bone health is a growing concern as the numbers affected by osteoporosis continue to rise, and an increasing elderly population suggests that these will grow further in the future. In Europe, osteoporosis causes around 1.1 million fractures each year. In light of recent research, and predicting future health problems, some researchers have called for recommended intake of vitamin D to be raised but the adequate amounts needed in the diet are still not known. The new study, published in today
Brain Cell Growth Boosted By DHEA Supplements
‘Anti-aging’ hormone DHEA Found to Boost Brain Cell Growth August 24, 2004
Human neural stem cells, exposed in a lab dish to the steroid DHEA, exhibit a remarkable uptick in growth rates, suggesting that the hormone may play a role in helping the brain produce new cells, according to a new study published this week in the online edition of the Proceedings of the National Academy of Sciences (PNAS).
The new work, conducted by a team of scientists at the University of Wisconsin-Madison, provides some of the first direct evidence of the biological effects of DHEA on the human nervous system, according to Clive Svendsen, the study’s senior author and an authority on brain stem cells at UW-Madison’s Waisman Center.
“What we saw was that DHEA significantly increased the division of the cells,” said Svendsen, a UW-Madison professor of anatomy and neurology. “It also increased the number of neurons produced by the stem cells, prompting increased neurogenesis of cells in culture.”
DHEA or dehydroepiandrosterone is among the most abundant naturally occurring steroids in the blood of young humans, but levels decline with age and its physiological effects are poorly understood.
A synthetic form of the hormone is sold over-the-counter as a dietary supplement in the US, thought to have anti-aging properties and to offer prevention against cancer and heart disease, Alzheimer’s and other diseases. But scientists know relatively little about the drug and its basic biological effects on humans.
“We don’t know much about DHEA, but this new work adds a piece to the puzzle,” said Svendsen, who conducted the study with colleagues Masatoshi Suzuki, Lynda S. Wright, Padma Marwah and Henry A. Lardy, all of UW-Madison. “This is the first real evidence of DHEA’s effects on human neural cells.”
Svendsen and Suzuki carried out the experiments by growing human fetal neural stem cells in culture. The cells form aggregates known as ‘neurospheres,’ which were exposed to a cocktail of DHEA and growth and inhibitory factors, and observed a 29 per cent increase in new brain cells compared to cells grown in a medium with the same factors, but without DHEA.
“We saw such a pure effect of DHEA,” Svendsen said.
“It’s the only steroid we tested that had such a direct effect on stem cell growth and new neuron formation,” according to Suzuki.
The new work is important because it provides a direct window to the controversial hormone’s effects on critical human cells. Similar studies have been conducted in mice and rats, but those models have shortcomings that are difficult to address, Svendsen notes.
“There are previous studies in rats that suggest DHEA is neuroprotective, but the problem with DHEA in rats is that it is not a major metabolite in that animal so its effects may not be the same as those seen in humans,” he said. According to Lardy, metabolic products of DHEA hormone have also been shown to aid memory retention in old mice.
Despite hints from the studies in rodents that DHEA may play a role in enhancing the brain and memory, the new findings reported in the PNAS article were a surprise, he said.
“We assumed the compounds we were testing would be more active than DHEA in brain stem cells,” Lardy explains. In previous studies, Lardy, with Wisconsin biochemistry colleagues James Ntambi and Brian Fox, showed that DHEA blocked a step in fat synthesis.
“The effects of DHEA on brain stem cells is a completely new finding,” said Lardy. “The problem of whether DHEA itself is having this effect, or if there’s another metabolite of the hormone involved, still exists.”
One of the intriguing aspects of the new work, according to Svendsen, is the possibility that DHEA could have some positive effects on the adult human brain.
It is known that DHEA amounts fall progressively during aging, and reduced levels of DHEA have been reported in both adolescents and adults with major depressive disorders. And given the fact that adult humans have neural stem cells that continue to make new neurons in some parts of the brain, there is a possibility that DHEA could play a role in moderating the genesis of new brain cells.