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Senior Citizen News Article
Prostate Cancer
Prostate Cancer: More Accurate Test, Longer Life Treatment Revealed in Two Studies
Feb. 18, 2005 - A simple urine test may improve the diagnosis of prostate cancer and a new treatment appears to prolong life for those stricken with this disease, according to two new studies. This is the most common cancer for older men, and 75 percent of all prostate cancer is found in men over 65.
Men middle-aged and senior citizens routinely get blood tests for prostate-specific antigen, or PSA, to screen for prostate cancer. However, PSA testing has shortcomings: many men with elevated PSAs don't have prostate cancer and undergo unnecessary biopsies, which can cause infertility, incontinence, and impotence. Other men do have prostate cancer, but have normal PSAs, allowing the cancer to spread undetected.
A preliminary study from Children's Hospital Boston, led by Dr. Bruce Zetter, shows that a simple urine test may improve upon PSA screening. Results appear in the Jan. 21 online edition of the journal Prostate.
The study on prolonging life was led by researchers at the University of California at San Francisco and found that the cancer "vaccine" increased survival, on average, by 4.5 months among men with advanced prostate cancer who no longer responded to other treatments. The results were made public yesterday at a prostate cancer symposium in Orlando, Fla.
Zetter, a researcher in the Vascular Biology Program at Children's, is interested in the role of cell motility -- cells' ability to move and travel -- in helping cancers to metastasize. He became especially interested in thymosin ß15, a protein that stimulates cell migration and promotes metastasis in prostate cancer. Unlike PSA, it is produced almost exclusively by cancer cells, and is detectable in urine.
In this study, Zetter and colleagues compared thymosin ß15 levels in urine samples from 121 men with prostate cancer, 15 men with other genitourinary cancers (kidney or bladder cancer), 81 men with non-malignant prostate disease (such as prostatitis), 73 men with other non-malignant urologic diseases (such as urinary tract infection), and 52 healthy men who served as controls. Thymosin ß15 levels were elevated in men with aggressive or untreated prostate cancer, but normal or near-normal in healthy men and men with other genitourinary diseases. Men with aggressive prostate cancer were 12 times more likely than the healthy controls to have elevated thymosin ß15.
Notably, nearly half of cancer patients whose PSA levels were considered normal tested positive for thymosin ß15. Conversely, many men with other genitourinary diseases had elevated PSAs, but normal thymosin ß15 values. When PSA and thymosin ß15 were combined, the combination detected prostate cancer more often than PSA testing alone, with far fewer false-positives.
Zetter, who is also Children's Chief Scientific Officer, is now following the long-term outcomes of men with prostate cancer to determine thymosin ß15's usefulness as a prognostic predictor in combination with PSA testing.
The Vascular Biology Program at Children's is also actively studying urinary markers for other cancers. In a small pilot study, Dr. Marsha Moses and postdoctoral fellow Dr. Roopali Roy recently found that a compound called ADAM 12, when detected in urine, is an early marker of breast cancer. Another group of markers will soon enter formal clinical trials in adults with prostate, breast, bladder, lung, and colon cancer.
For more information about Children’s Hospital Boston visit: http://www.childrenshospital.org/research/.
Prolonging Life
An innovative treatment for prostate cancer that uses a person's own immune system has been found for the first time to prolong the lives of patients with the disease, the most common form of cancer among men.
Although the benefit of prolonging live by a few months seems moderate, doctors said it is a significant improvement for patients with few options and little hope. They also said it represents an important validation for cancer vaccines, a new approach that doesn't prevent cancer -- the classic approach of a vaccine -- but instead rallies the immune system to fight the disease.
Cancer vaccines are emerging as a promising fourth way to combat cancer that could complement the existing treatments of chemotherapy, radiation and surgery. Vaccines are particularly appealing to patients because they don't have the debilitating side effects associated with chemotherapy and radiation.
"This is really the very first study that has shown a survival advantage for any (cancer) vaccine," said Dr. Eric J. Small, a UCSF oncologist who was the principal investigator of the study.
"What that does for the field is very exciting. It tells us that we're on the verge of a new era of therapeutics that will be targeting the immune system."
Small will present the results of the Phase III clinical study Saturday at the Multidisciplinary Prostate Cancer Symposium in Orlando.
Prostate cancer is the most common type of cancer among men, with an estimated 232,090 cases diagnosed each year. More than 30,300 men die annually of the disease, making it the second-leading cause of cancer deaths among men after lung cancer.
The study involved 127 men with prostate cancer that had spread to their bones and who no longer responded to hormone therapy, the conventional treatment, but who had not yet experienced pain from the disease. Patients were given either a placebo or the vaccine -- three doses over a six-week period -- and were followed for three years.
Patients who received the vaccine survived, on average, for 25.9 months, compared with 21.4 months for men who received a placebo, a nearly 20 percent survival improvement. After three years, three times as many vaccine patients (34 percent) were still alive, compared with the placebo group (11 percent).
Side effects from the vaccine -- some fever and shaking -- were relatively minor and disappeared within a couple of days.
Dr. Nicholas Vogelzang, an independent oncologist who also heads the Nevada Cancer Institute in Las Vegas, said that while the size of the trial was relatively modest, the results were "consistent with what we think would be the effect were the immune system to attack prostate cancer. It would slow it down. It wouldn't cure it, but people would live longer."
Small cautioned that the vaccine may not be for all patients, including those with early-stage prostate cancer and people with "explosive terminal cancer." But he said it represents an important new option for men with advanced prostate cancer that has spread but who have yet to experience pain from the cancer.
"It gives our patients an additional treatment option," Small said. "It offers them hope that there's something that can control the disease where there aren't a lot of other options."
The only other option for such patients, he noted, is a new chemotherapy drug, taxotere, approved by the FDA last year, which can prolong survival but has serious side effects.
The vaccine, which is called Provenge, is being developed by Dendreon, a Seattle-based biotechnology company. The latest study is a critical step in winning marketing approval from the Food and Drug Administration, which has already granted the vaccine "fast track" status.
More importantly, the UCSF study represents an important proof of concept for cancer vaccines and using the immune system to fight cancer. Cancer vaccines are under development to treat melanoma, lymphoma, leukemia and cancers of the colon, breast, kidney and pancreas as well as the prostate.
Although the human immune system is programmed to defend the body against invaders such as a cold virus, its ability to fight cancer is limited because it doesn't easily recognize tumor cells as foreign. Moreover, one of the effects of cancer's malignant growth is to suppress the body's immune system.
Cancer vaccines are designed to rev up the immune system and teach the body's disease-fighting cells -- antibodies and so-called killer T-cells -- to recognize subtle differences in the cancerous cells so they can attack the cancerous cells as "foreign" invaders, while leaving healthy cells alone.
Provenge, the prostate cancer vaccine, takes advantage of a specialized immune system cell, called a dendritic cell, that chews up foreign invaders and then "presents" pieces of the invaders on the cell surface so other immune system cells, namely killer T-cells, can recognize and destroy the invaders.
Patients' blood is collected and enriched to increase the population of dendritic cells. These cells are then cultured with a specific protein common to 95 percent of all prostate cancer cells.
The dendritic cells digest this protein. When the dendritic cells are put back into patients, they signal killer T-cells to destroy any other cells with the telltale protein.
Source: AP
Senior Citizen Aticles | Prostate Cancer
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