Research Highlights: Prostate Cancer
Exploring Omega-3s for Prostate Cancer Treatment
Linda A. deGraffenried, assistant professor at the University of Texas Health Science Center at San Antonio, is turning up some promising findings on how fish oils may play a role in treating an advanced form of prostate cancer.
Androgen deprivation therapy is a common treatment because androgen stimulates prostate cancer growth. Androgen is a class of hormones. Testosterone, which promotes male characteristics, is one of the most familiar androgens. Starving cells of androgen is successful at first, but typically within two to three years, some of the cancer cells begin to thrive again.
The Omega-3 Link
Dr. deGraffenried’s research focuses on the role omega-3 fatty acids may play in preventing androgen-deprived prostate cancer cells from starting to grow again. Omega-3 fatty acids are essential fats – the body cannot make them – found in fish, such as salmon, tuna, and mackerel.
Laboratory studies have shown that when androgen-deprived cells were exposed to omega-3s, cell growth stopped. Omega-6 is another essential fatty acid; it is found in seeds, nuts, and vegetable oils. When androgen-deprived cells were exposed to omega-6s, cells continued to grow.
Dr. deGraffenried is taking her research one step further by examining how omega-3s may stop cell growth. Her work is focusing on the androgen receptor, which plays a key role in regulating androgen. Scientists have found that if the androgen receptor is blocked, prostate cancer cell growth stops.
Genetic analysis showed that omega-3 fatty acids stopped the androgen-receptor gene from functioning, while the omega-6 fatty acids did not. The goal is to ensure that patients will consume the amount of omega-3 that is effective and able to be incorporated into a healthful diet.
There is not yet enough evidence to show that omega-3s can help prostate cancer patients, says Sarah Wally, a registered dietician at AICR. But AICR recommends replacing saturated and trans fats with healthy fats, like omega-3s.
Source: American Institute For Cancer Research www.aicr.org
CANSA Comment: CANSA recommends replacing products that contain saturated and trans fat with products containing healthy fats.
Lowering Cholesterol May Also Lower Prostate Cancer Risk
Men who keep their cholesterol down might also help lower their levels of prostate specific antigen, a protein that can warn of prostate cancer, a new study says.
“Prostate cancer is controlled by the male hormone testosterone. The main molecule that forms testosterone is cholesterol,” said Dr. Murugesan Manoharan, an associate professor at the University of Miami Sylvester Comprehensive Cancer Center, who was not involved in the study. “So it is known that prostate cancer is related to testosterone, and testosterone is related to cholesterol.”
The study’s inference is that by lowering cholesterol, you also lower PSA, which in turn may reduce the risk of prostate cancer, Manoharan said. “Obviously this is a very small study and does not confirm anything, but it is a very good start that could lead to something more at a later point,” he said.
For the study, researchers collected data on 1,214 men taking cholesterol-lowering drugs called statins. The researchers found that PSA levels were lower after starting the statins, and the drop in PSA was proportional to the drop in cholesterol.
The results of the study confirm those of a previous study that also found that lowering cholesterol lowered PSA, the researchers noted. If confirmed, the results of the new study would provide more evidence that cholesterol plays a role in the biology of the prostate, the researchers said.
It’s still not clear, however, whether lowering PSA with cholesterol-lowering drugs may actually hide developing prostate cancer, Manoharan said. “Bringing down the PSA levels artificially does not mean necessarily decreasing the chance of developing prostate cancer,” he said. “It might just bring the blood test reading down without reducing the risk of prostate cancer. In fact, we could miss the prostate cancer, because the PSA readings are on the lower side.” Manoharan said the new findings need to be studied further.
Source: MedlinePlus http://medlineplus.gov
Prostate Cancer Vaccine Looks Promising in Early Trial
A therapeutic vaccine to treat prostate cancer appears safe and may be effective, according to the results of an early trial.
The vaccine could give hope to men with metastatic prostate cancer by activating their immune systems to fight the disease. The vaccine was developed to enable a patient’s immune system to produce anti-antigens and attack cancer cells, which can improve quality of life and extend survival.
“The primary objective of the study was to determine whether or not the vaccine was safe or whether it induced any serious adverse events,” said lead researcher Dr. David Lubaroff, director of urology research at the University of Iowa. “The vaccine was quite safe.”
In addition, the researchers wanted to see if the vaccine produced an immune response to prostate specific antigen (PSA).
“We found that 68 to 70 percent of the patients in the trial demonstrated immune responses to PSA,” Lubaroff said. “This was their last resort, and we were encouraged by the fact that we could detect any immune response in these patients.”
In the trial, Lubaroff’s team tested the adenovirus/PSA vaccine in 32 men with metastatic prostate cancer. The men were treated with one of three different doses of the vaccine and followed for 12 months.
In addition to developing immune responses to PSA, 57 percent of the patients survived longer than predicted. Based on these results, Lubaroff’s group has started a phase II trial, which will determine whether the immune response and survival seen in this trial is really therapeutically meaningful in a larger number of patients.
“If this vaccine proves to induce a strong anti-PSA immune response, and if there is a correlation between this PSA response and an effect on the disease, then we could use this vaccine as another therapy,” Lubaroff said.
One expert is skeptical that this vaccine will ever prove to be a viable treatment. “I think about all you can prove from this kind of study is safety,” said Dr. Bruce Roth, a professor of medicine and urology at Vanderbilt University. “But that’s a world of difference from saying that there is evidence of efficacy.” Roth doesn’t think changes in PSA in this kind of trial are enough to prove the vaccine works.
Source: MedlinePlus http://medlineplus.gov
CANSA comment: Cancer research articles published in the media and medical journals often refer to studies in the early stages and the findings need to be studied further to uncover any discrepancies or confirm the outcomes of the initial study.