Normal Cells May Predict Cancer Virulence
THURSDAY, Aug. 28 (HealthDay News) -- Characteristics of normal cells which are present long before any tumor appears may determine how virulent a particular cancer is going to be, new research suggests.
Such cells may travel early on to distant sites in the body, residing innocently there until certain cancer genes are turned on.
"It's definitely conceptually very profound," said Dr. Katrina Podsypanina, a senior research scientist at Memorial-Sloan Kettering Cancer Center in New York City. "Our data seems to point toward the inherent decision that is made when the tumor is formed whether it is highly malignant or not. Moreover, since the characteristic might be dependent on the normal cell status, one might imagine that they might be different between individuals."
The study's senior author is Harold Varmus, who won the 1989 Nobel Prize for his work in cancer genetics and later went on to become director of the National Institutes of Health.
The finding implies that treatments that only target malignant cells may not be effective.
So far, however, the findings have only been shown in mice, and the research involved certain processes that were imposed which wouldn't normally occur in the human body.
"This does suggest that cells can sit for a long time, then be activated," said Dr. Claudine Isaacs, director of the clinical breast cancer program at Georgetown's Lombardi Comprehensive Cancer Center in Washington, D.C. "But these cells were injected into the circulation. Normal breast cells are not supposed to be in the circulation."
Also, the normal cells didn't form tumors until activated.
Conventional medical wisdom holds that the spread of a cancer occurs relatively late in the life of a cancer, happening only after cells from the primary tumor have undergone enough mutations to switch on different cancer genes.
Podsypanina and her colleagues performed a series of experiments in mice.
First, they injected normal mammary cells that contained cancer-inducing oncogenes, which could be switched on and off. These cells migrated through the bloodstream to the lungs, residing there for four months. They did not begin to grow aggressively until the oncogenes had been turned on, but they did so without first going through the stage of being a primary tumor.
Next, they injected normal cells without manipulating any oncogenes.
"Cells that did not have any oncogenes in them and do not transform spontaneously as per all published studies, we could see little colonies of these cells when we inspected the lungs," Podsypanina said. "At no point, never, did we see a solid vision that would resemble metastatic colonies, [but] it appears that every time we looked at the animal, the colonies appeared to be larger."
When these normal ectopic cells were injected back into a new generation of mice, they developed into normal mammary glands.
"It's a beginning," Podsypanina said. "It's an important step to show whether or not the first step of the metastatic cascade is something a normal cell can accomplish."
Visit the American Cancer Society for more on oncogenes.
Nonmelanoma Skin Cancer Ups Risk for Other Cancers
TUESDAY, Aug. 26 (HealthDay News) -- People with a history of nonmelanoma skin cancer face twice the risk of developing other malignancies, a new study finds.
Every year in the United States, about 1 million people are diagnosed with nonmelanoma skin cancers, according to the American Cancer Society. Developing these tumors is known to increase the risk for melanoma, the most serious form of skin cancer. But the link between skin cancer and cancers at other body sites is just beginning to be explored.
Now, researchers reporting online Aug. 26 in the Journal of the National Cancer Institute say that a history of nonmelanoma lesions doubles the odds for a subsequent cancer. "That's not just cancer related to melanoma or other skin cancers," noted lead researcher Anthony Alberg, from the Medical University of South Carolina.
In this study, the increased risk was seen for lung cancer, colon and breast cancer, Alberg said. "For prostate cancer, the trend was in the direction of increased risk, but the association was weaker and not statistically significant," he said.
Alberg believes the increased risk may be due to a weakened ability to repair DNA damage to cells. "People who have suboptimal ability to repair DNA damage that the sun can cause are far more likely to get nonmelanoma skin cancer. We are hypothesizing that that might also be the link to why there is a greater increased cancer risk in general," he said.
For the study, Alberg's team looked at the risk of developing cancer among 769 people with a history of nonmelanoma skin cancer. The researchers compared these people to 18,405 people with no history of skin cancer.
Over 16 years of follow-up, the researchers found that the incidence of cancers was 293.5 per 10,000 person-years among people with a history of skin cancer, compared to 77.8 per 10,000 among people without a history of the disease.
In addition, the younger a person got a nonmelanoma skin cancer, the higher his or her risk of developing other cancers, Alberg said.
Dr. Robin Ashinoff, a dermatologist at New York University Medical Center, New York City, agreed that the inability to repair DNA damage associated with nonmelanoma skin cancer may make developing other cancers more likely.
"It is not unreasonable to suppose that patients with nonmelanoma skin cancers, especially if diagnosed when the patient is young, puts that person in a higher risk category of systemic cancers," Ashinoff said.
People who develop skin cancers may have inherited a family tendency for other cancers because of inadequate ability to repair DNA, Ashinoff said. "In addition, these patients are followed closely for further skin cancers, and therefore may have an increased diagnosis of other cancers, because they are plugged into the medical system," she noted.
"Our skin cancer patients should know that they may be at increased for a wide variety of cancers like breast, lung and colon, and should not ignore early signs and symptoms if they occur," Ashinoff advised.
Dr. Martin Weinstock, chair of the skin cancer advisory committee at the American Cancer Society, said awareness and testing are key.
"People who have had skin cancers should make sure they are up-to-date on all their screening tests," Weinstock said. "They should be up-to-date on their colonoscopies, fecal occult blood and mammograms and Pap smears," he said.
In addition, people need to protect themselves from UV exposure, so they don't develop skin cancer in the first place, Weinstock said.
In another report, published in the same issue of the journal, researchers found that patients who use blood pressure-lowering drugs called angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) have a lower risk of developing basal or squamous cell skin cancers.
In research led by Jennifer Christian, from the VA Medical Center and Brown University in Providence, R.I., researchers found that patients taking ACE inhibitors or ARBs had a 39 percent lower risk of developing basal cell skin cancer and a 33 percent lower risk of developing squamous cell skin cancer.
Why these drugs lower the risk of skin cancer isn't known, the researchers said.
For more on skin cancer, visit the American Cancer Society .
Obese Men Face Twin Threat From Prostate Cancer
FRIDAY, Aug. 8 (HealthDay News) -- The standard screening test for prostate cancer may not be accurate for obese men, leaving them more vulnerable to the disease, and surgery is less likely to be effective for them, a new pair of studies found.
"Obese men are more likely to be diagnosed with an aggressive form of the disease," said Dr. Stephen Freedland, an associate professor of urology and pathology at the Duke University Prostate Center, and an author of one of the studies.
The reason: The blood test that looks for elevated levels of the protein prostate-specific antigen (PSA), indicating a heightened cancer risk, doesn't seem as reliable for obese men, Freedland said.
"Our assumption is that these men have more blood volume, so PSA gets diluted, he said. "By the time obese men get to elevated levels, the cancer is more advanced."
The study, published online Friday in the journal BJU International included nearly 3,400 men who had PSA tests. The researchers found that the risk of an aggressive cancer was doubled in obese men diagnosed because of high PSA levels. No such association was found for obese men diagnosed by a digital rectal examination, in which the physician feels for an abnormally large prostate gland.
Prostate cancer is suspected when the PSA reading is 4 or higher. The current recommendation is for men aged 50 and older to be offered an annual PSA test, with explanations of its possible risks and benefits. A federal preventive medicine committee this week said that PSA screening should not be done for men aged 75 and older because the risks outweigh the benefits.
"I'm not sure that we should check obese men more often," Freedland said. "But we should have a higher [PSA] index of suspicion of what is not normal -- 3.4 rather than 4; for really obese men, 3.2."
The Duke study measured obesity using body-mass index, which is a ratio of weight to height. Obesity is defined as a BMI of 30 or more.
A second report from Duke in the same issue of the journal found that excess weight influenced the outcome of surgery for prostate cancer. Men with a BMI of 35 or higher were nearly 60 percent more likely to have a recurrence of the cancer than thinner men, the study of 1,434 men found.
One reason is "the difficulty of operating on obese men in general," said study author Dr. Jayakrishnan Jayachandran, a urology oncology fellow at the Duke Prostate Cancer Center. "The prostate is a narrow thing to operate on, and when there is a big wad of fat in your way, if the abdominal wall is thick, it becomes a technical issue."
The result is that not all the cancer may be removed, which means a recurrence after time, Jayachandran said. "The only thing we can think of is that when you operate on obese people, you have to be more careful," he said.
The studies results apply to men who might not regard themselves as obese, Freedland said. "We can't forget that when we use the term, we are not just talking about very large men," he said. "A man who is 5 foot 9 and weighs 203 pounds would be considered obese."
Jayachandran added, "We are not screening these obese men effectively and are not doing as good a job surgically as could be done."
To learn more about prostate cancer, visit the U.S. National Cancer Institute.
Breast CT Scans Could Be Comfortable Alternative to Mammograms
FRIDAY, Aug. 1 (HealthDay News) -- For women who find traditional mammograms painful, new research suggests there may one day be a more comfortable alternative.
Breast CT scans showed some advantages over traditional mammograms, said study author John Boone, vice chairman of radiology at the University of California Davis Medical Center. He presented the findings this week at the American Association of Physicists in Medicine annual meeting, in Houston.
"Breast cancer shows up on a mammogram or imaging in two different ways -- a mass lesion or a spot," Boone explained. These spots are called microcalcifications, and they can signal the beginnings of a tumor.
In the CT breast exam, the scanner rotates around the breast to create a three-dimensional picture of the breast. The total radiation dose in the scan Boone used is the same as in a conventional mammogram, he said. In this study, 160 women were screened this way.
But the breasts are not compressed between plates, as in a traditional mammogram. Instead, the woman lies face down on a special table with one breast suspended through an opening.
"We feel the breast CT was superior to traditional mammography for mass lesions, but mammography remains superior over breast CT for microcalcifications," he said.
Several other centers are also studying breast CT, he noted. The role of breast CT is evolving, Boone said, and will depend on continuing research and how it bears out.
In his research, Boone and his colleagues have also began to study another prototype device which incorporates a positron emission tomography (PET) scanner into the CT scanner. The PET scanner can track the metabolic activity of a tumor, if present, so doctors can pinpoint the tumor and evaluate the effect of treatment.
Breast CT scans may be widely available in three to five years, Boone predicted.
The technology is experimental, cautioned Robert Smith, director of cancer screening for the American Cancer Society. "One of the things that is appealing is comfort on the part of the patient," he said.
But, he added, if it is going to play a role in breast imaging, "it has to be just as accurate in finding breast cancer [as mammography], and should not generate a higher rate of false positives."
In other presentations at the meeting, University of Wisconsin researchers reported on improvements in tools to make a procedure called modulated electron therapy (MERT) more effective in treating tumors of the chest wall after mastectomy.
And University of Chicago researchers discussed a new automated computer image analysis technique that better characterizes and diagnoses early breast cancers. The computer program makes use of facts known about how lesions respond to injected contrast agents to help doctors describe the lesion's characteristics. For instance, malignant lesions wash out contrast material more quickly than benign ones.
To learn more about CT scans, visit the American College of Radiology .