MONDAY, Oct. 28 (HealthDay News) -- Doctors believe they have
found telltale signs that can indicate whether breast or prostate
malignancies will remain dormant or develop into aggressive
These indicators -- called "biomarkers" -- are found in the
blood or tissues of people with breast or prostate cancer.
Researchers hope to one day use them to develop tests that will
determine the cancer treatment each patient will need.
"It's a dream, I would say, at the moment. And it's a hope," Dr. Clifford Hudis, president of the American Society of Clinical Oncology (ASCO), said of the potential for using biomarkers to help determine a person's risk of aggressive cancer. "But it's not yet clinically validated, and it's not useful yet for patients."
Two research teams are scheduled to present their findings on
possible biomarkers for breast and prostate cancer this week at the
International Conference on Frontiers in Cancer Prevention
Research, hosted by the American Association for Cancer Research,
at the National Harbor in Oxon Hill, Md.
Doctors with the University of Pennsylvania reported that the
presence of a protein called Vav2 in breast tissue might indicate
whether a precancerous condition called ductal carcinoma in situ,
or DCIS, will develop into invasive breast cancer.
Meanwhile, Johns Hopkins researchers said chromosomes in a man's
blood might provide evidence that a prostate cancer will develop in
an aggressive manner.
There is widespread concern that in both DCIS and prostate
cancer, doctors tend to overtreat patients.
Two-thirds of DCIS cases never progress to full-fledged invasive
cancer, ASCO's Hudis said, "which means when we treat DCIS, we are
treating many people who would never have developed invasive
And few men with prostate cancer actually die as a result of the
cancer, which has prompted much debate over whether doctors should
treat it, said William Phelps, program director for the American
Cancer Society. The available treatments often lead to unpleasant
side effects such as incontinence and impotence.
"The treatments themselves are not very good," Phelps said of prostate cancer. "If the treatments were fairly nondamaging, you'd just say, 'Well, let's treat everybody.'"
The Pennsylvania researchers examined 211 remnants of tissue
samples that had been taken to diagnose breast cancer. Of the
samples, 42 were normal breast tissue, 71 were DCIS and 98 were
invasive breast cancers.
DCIS involves the presence of abnormal cells inside a milk duct
in the breast. In "pure" DCIS, the cells have not become cancerous
and started to spread, said senior research investigator Marina
Guvakova, an adjunct assistant professor in the department of
surgery at the University of Pennsylvania.
However, there also are forms of DCIS that involve either fully
invasive cancer or micro-invasive cancer, in which fewer than 10
percent of the abnormal cells have spread beyond the original
The doctors found that the amount of Vav2 in pure DCIS is as low
as in normal breast tissue, but that presence of the protein
gradually increased in DCIS with micro-invasive cancer. The highest
levels of Vav2 were found in DCIS with invasive cancer.
"Those lesions are twice as likely to have associated invasive breast cancer as lesions with low expression of Vav2," Guvakova said.
Statistical analysis revealed that the ability of Vav2 to
predict progressive cancer in DCIS was 0.71. A value of 1 means the
marker has a perfect discriminating power, and a value of 0.5 means
that the marker's discriminating power is no better than
"It is, in statistical terms, considered a very good predictor," Guvakova said. "It's definitely not by chance."
Their findings have not been published, but once that is
accomplished the team will begin designing a study that would
attempt to predict the behavior of DCIS in current patients, she
The Johns Hopkins research into prostate cancer focused on
telomeres, which are sequences of genetic material located at the
ends of chromosomes, that protect them. They function in much the
same way that the plastic tips at the ends of a shoelace protect
the lace from unraveling.
Doctors examined the DNA in immune cells drawn from blood
samples provided by 441 men who later developed prostate cancer, as
well as 421 men who did not develop prostate cancer.
The researchers found that among the men who developed prostate
cancer, those with the shortest telomeres in their immune cell
chromosomes were more than twice as likely to have developed
aggressive prostate cancer compared to those men who had the
Smoking appears to play a strong role. When the researchers
narrowed their analysis down to current or former smokers, they
found that those with the shortest telomeres in their immune cells
were more than four times as likely to have developed aggressive
"We don't yet know why having short telomeres in blood leukocytes [white blood cells] seems to be associated with risk of aggressive prostate cancer," researcher Elizabeth Platz, a professor in the department of epidemiology at Johns Hopkins Bloomberg School of Public Health in Baltimore, said in a conference news release.
"It may tell us about a person's exposure to factors that increase their risk of prostate cancer, or it may be an indication of an inherent inability to maintain telomere length, which could put them at increased risk for this disease," Platz said. "If so, it might be that measuring telomere length in blood leukocytes could even predict risk of many different forms of cancer."
Because the studies were presented at a medical meeting, the
data and conclusions should be viewed as preliminary until
published in a peer-reviewed journal.
For more about breast cancer, visit the
U.S. National Cancer Institute.
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