WEDNESDAY, Jan. 9 (HealthDay News) -- Researchers have zeroed in on a handful of tiny ribonucleic acid (RNA) molecules that seem to control whether or not breast cancer travels to the lung and bone.

These "microRNAs" essentially serve as brakes on the proliferation of cancer. When they are missing, that allows the disease to spread freely. When they are restored, however, the cancer cells lose some of their ability to metastasize, the Memorial Sloan-Kettering Cancer Center scientists report.

The work has implications both for predicting which cancers are aggressive and establishing new targets for drug therapy down the line.

"It's very interesting early research and may avail one day to discovering agents to suppress the growth of metastases," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La. "It's very fine research."

The findings could also help individualize cancer therapies.

"One of the fundamental lessons which should be reinforced from this study is that breast cancer is not one disease. It is clearly a family of diseases and identifying mechanisms that turn on or turn off genes in one cancer helps us with what I would call class prediction," added Dr. Patrick Borgen, director of the Brooklyn Breast Cancer Project at Maimonides Cancer Center in New York City. "This is important, because it gives us another box to classify breast cancers in. The primary reason that more progress has not been made is that we've used a one-size-fits-all treatment paradigm for breast cancer."

"Researchers have opened up a whole new window on ways to look at subsetting breast cancers. That holds short-term possibilities to go back and look for a predictor of prognosis or predictor of response to therapy based on these small RNA molecules. That really is a very tangible short-term goal," Borgen added. "That, in and of itself, would be exciting enough, but unlike most prognostic factors that we identify, this is one [that] represents a potential target for intervention. I think this is really exciting. I think this is the real deal."

If patients with more ominous cancers can be identified, doctors can then focus on administering more aggressive therapies from the start.

Most deaths from cancer occur after a tumor has metastasized or spread to other parts of the body.

"Metastasis is the overwhelming cause of death of patients that we see from cancer," confirmed study author Dr. Sohail F. Tavazoie, a postdoctoral fellow in the oncology-hematology fellowship program at Sloan-Kettering, in New York City.

But why are some cancers prone to spread while others are not?

Part of the answer lies in microRNAs, which subdue the activity of sets of genes linked to metastasis.

DNA is made up two strands (a double helix) of "letters" that contain all the information needed to create cells. RNAs are single-stranded copies of segments of the DNA, Tavazoie explained. While many RNAs are translated into proteins, others (including microRNAs) have the power to shut off genes.

The microRNAs appear to act as master "supervisor" or regulator of these sets of genes.

Tavazoie hypothesized that some of these microRNAs are missing in more dangerous cancers. "The brakes are lifted, so a group of genes could actually be activated," he explained.

Tavazoie and his colleagues, who published their findings in the Jan. 10 issue of Nature, investigated how microRNAs might play a role in controlling the expression of genes that in turn control metastases.

First, they compared microRNAs produced by metastatic human cancerous cells with those produced by non-metastatic cancer cells in the laboratory.

"We saw that the highly metastatic cancer cells had lost some of these small RNA molecules," Tavazoie said.

Could some of these molecules be the so-called supervisors of other genes involved in cancer becoming lethal?

In fact, when three of eight microRNAs identified were put back into aggressive cells, those cells backed down, becoming less likely to spread. These experiments were done in mice programmed with human cancer cells.

The researchers then took the project a step further, predicting that women with breast cancer who had lost these small RNA molecules would be more likely to have an aggressive form of cancer.

"Indeed, when I looked at two of the microRNAs, women who had lost either of them had a significantly higher risk for having the cancers come back," Tavazoie said. "This supported the hypothesis that these small RNA molecules could be playing an important role in regulating the spread of cancers."

Tavazoie then identified six genes or "players" that one of these "supervisors" regulated. He took out two of the genes in lab mice and watched the cancer become more aggressive.

"The 'supervisors' put the brakes on the 'players,' so when you take out the players, the cells can't spread any more," Tavazoie explained.

When he analyzed genes from more than 300 cancer patients, he found that women with higher levels of the six genes had a greater chance of having the cancer move to the lung and bone.

"The story suggests that these small RNAs seem to play an important supervisory or regulatory role in putting a brake on some of these genes," Tavazoie said. "In women whose cancers have lost this brake, it seems that they're more likely for the cancer to spread."

More information

The American Cancer Society   has more on breast cancer.

MONDAY, Jan. 7 (HealthDay News) -- Men who father children may be at higher risk of prostate cancer compared to those who forego the life experience, a Danish study suggests.

The large-scale study looked at all men born in Denmark between 1935 and 1988. It found that childless men had a 17 percent lower incidence of prostate cancer than fathers did.

The reasons why remain unclear.

"It is not possible from the current data to point out what factors associated with childlessness, whether biologic, environmental, social or behavioral, were responsible for the observed reduction in prostate cancer risk," wrote researchers at the Statens Serum Institut, in Copenhagen.

The study is published in the Jan. 7 online edition of Cancer, and will appear in the journal's Feb. 15 print edition.

The findings echo those of a prior Scandinavian study, published in 2005, which looked at more than 48,800 cases of prostate cancer. That report also found a 17 percent lower incidence of prostate cancer among childless men.

In neither of the two studies did the gender of the children fathered affect the man's risk of prostate cancer. However, one large-scale study conducted several years ago in Israel found that the malignancy was 40 percent more common among men with no sons.

Dr. Susan Harlap, now a professor of epidemiology at New York University, led that Israeli study. She said the differing results reflect the complex factors, genetic and otherwise, that underlie prostate cancer risk throughout the world.

"The incidence of prostate cancer is different in Israeli Jews than in northwestern Europeans," Harlap said. "It may be a different disease, and there may be a different set of causes. We do know there are genetic causes of prostate cancer, and there could be different sets of genes in Israeli Jews than in northwestern Europeans."

A relationship between prostate cancer risk and having no sons would point to a mutation in the Y chromosome, which determines the male sex of a child. But there are complexities to such a relationship, Harlap noted.

"If the effect is due to Y chromosomes, they are quite specific to ethnic groups," she said. "Israeli Jews are different from Danes and Swedes."

The complexity of the issue is also illustrated by the different findings of the two Scandinavian studies about fatherhood and risk. The new Danish report finds that "among fathers, a significant trend was observed of gradually reduced prostate cancer with increasing number of children" -- in other words, fatherhood was linked to an increased risk for prostate cancer, but fathering more children begins to bring that risk down again. In contrast, the earlier study found "no further change in risk associated with fathering of more than two children."

Dr. Otis Brawley, chief medical officer of the American Cancer Society, was less than impressed by the Copenhagen findings, however. Despite the large numbers, the result was "just barely statistically significant," Brawley said, and could be the result of pure chance.

In a study of this kind, he said, "you occasionally get something that is statistically significant but is not really significant biologically."

In any case, men shouldn't make decisions on fatherhood based on the study results, Brawley stressed. "I would never suggest to men that their wives not get pregnant so they don't get prostate cancer," he said. "Lack of fatherhood is not a strong preventive of prostate cancer."

Any relationship that does exist is probably very weak, Brawley said. "If there is a real correlation, I would like to know what the true cause is," he said. "I suspect we will never know."

More information

There's more on prostate cancer at the American Cancer Society  .

THURSDAY, Dec. 20 (HealthDay News) -- People diagnosed with cancer who don't have health insurance are more likely to die because they are less likely to get screening tests and so are typically diagnosed with advanced disease, a new study from the American Cancer Society finds.

The finding proffers strong evidence that differences in cancer survival are directly related to lack of access to health care.

"If you are uninsured, and you are diagnosed with cancer, you have a 60 percent greater chance of dying from cancer than if you were insured and diagnosed with cancer," said Dr. Otis Brawley, chief medical officer at the cancer society.

"There is not a cohort of insured and a cohort of uninsured cancer patients that have the same five-year survival," Brawley added. "It's always the uninsured who do worse."

Part of the problem is that uninsured people don't have access to screenings, Brawley said. "But part of it is that uninsured people don't have access to the best doctors or have access to good doctors who are overwhelmed. The end result is the quality of care the poor folks get is not as good as the quality of care of the wealthier or the insured," he said.

There are also people who are underinsured, Brawley said. While these people have access to care, high co-pays and deductibles make the care unaffordable, particularly high-priced chemotherapy drugs, he noted.

"Where it becomes frightening and morally reprehensible is people who have significant pain and can't get narcotics and other pain medications they need, because they can't afford them," Brawley said.

People don't realize they are underinsured until after they have gotten sick, Brawley said. "There are a substantial number of Americans who don't realize they are a cancer diagnosis away from economic disaster," he noted.

The study, in the January/February issue of CA: A Cancer Journal for Clinicians, used data from the National Cancer Database, which is the only national registry that collects data on patient insurance.

The report is an overview of systems of health insurance in the United States. It has data on the association between health insurance, screening, stage at diagnosis, and survival for breast and colorectal cancer.

The link between access to care and cancer outcomes is particularly striking for cancers that can be prevented or found early by screening and for which there are effective treatments, including breast and colorectal cancer.

Only about 38.1 percent of uninsured women aged 40 to 64 have had a mammogram in the past two years, compared with 74.5 percent of insured women. In addition, 20 percent to 30 percent of uninsured women are diagnosed with late-stage breast cancer, compared with 10 percent to 15 percent of women with private insurance, according to the study.

Uninsured women are less likely to be diagnosed with early breast cancer than women who are privately insured. This disparity was greatest among white women, where almost 50 percent of those with private insurance were diagnosed with early-stage cancer, compared with fewer than 35 percent of uninsured white women.

Moreover, 89 percent of insured white women were living five years after breast cancer diagnosis compared with 76 percent of uninsured white women. For black women, five-year survival rates are 81 percent for those with private insurance and 65 percent for uninsured women.

For men and women aged 50 to 64 who have private insurance, 48.3 percent were screened for colorectal cancer in the past 10 years compared with fewer than 18.8 percent of the uninsured.

In addition, uninsured patients are more likely than those with private insurance to be diagnosed with stage IV colorectal cancer and less likely to be diagnosed with stage I colorectal cancer, the researchers found.

For whites, 66 percent of insured patients survive colorectal cancer for five years, compared with 50 percent of those without insurance. For blacks, five-year survival rates are 41 percent among the uninsured compared with 60 percent among privately insured patients.

Additional findings in the study include:

• Uninsured women were less likely to have a Pap test in the past three years than insured women (68 percent vs. 87.9 percent).
• Among insured men, 37.1 percent had a prostate specific antigen test, compared with 14 percent of uninsured men.
• People aged 18 to 24 have the highest probability of being uninsured.
• Lower-income people are more likely to be uninsured.
• Blacks, Hispanics, Asian American/Pacific Islanders, and American Indian/Alaska Natives are more likely to be uninsured than whites.
• Of those without insurance, 53.6 percent have no usual source of health care.
• The uninsured are more likely to delay care, not receive care, and not obtain prescription drugs because of costs.
• Among people who saw a health-care provider, those without insurance were less likely to be advised to quit smoking or lose weight.

Brawley noted that while some of the uninsured qualify for Medicaid, coverage doesn't begin until the cancer has been diagnosed.

"You have someone who is uninsured and poor -- gets none of the screenings, gets none of the early detection opportunities -- when they finally go to the doctor, it's because they are so sick, they can no longer go to work, or their family is forcing them to go to the emergency room," Brawley said. "What you have is someone who a year ago we could, relatively cheaply, fix, maybe even cure, but now that they have ignored their symptoms, it's no longer fixable, we are going to treat them, but the treatment is going to be very expensive."

The remedy to the problem is "making sure that everyone who wants health insurance can get affordable health insurance," Brawley said. "In this country, we need to have an open conversation about this issue."

One expert thinks this study highlights the need for a health insurance program that covers everyone.

"Sadly, many Americans must face the challenges of cancer with no insurance coverage, or with Medicaid, which is often grossly inadequate as coverage," said Dr. Steffie Woolhandler, an associate professor of medicine at Harvard Medical School and a co-founder of Physicians for a National Health Program.

For these cancer patients, diagnosis is delayed and survival is shortened, Woolhandler said. "We need nonprofit national health insurance to be sure that everyone gets the health care they need, particularly people with cancer."

More information

For more on health insurance, visit Physicians for a National Health Program  .

MONDAY, Dec. 17 (HealthDay News) -- Something as common and available as sunlight may help prevent some lung cancers, researchers say.

A new study finds that lower levels of the sun's ultraviolet B (UVB) rays are associated with a higher incidence of lung cancer across 111 countries.

Still, that doesn't mean that spending more time in the sun will ever offset the risks that come with smoking, according to the study, which is published in the January issue of the Journal of Epidemiology and Community Health.

It's also not an excuse to trade skin cancer for lung cancer.

"The problem is that people might over-interpret this and stay in the sun for hours," said Cedric Garland, study senior author, professor of family and preventive medicine at the University of California, San Diego (UCSD), and participating member at the Moores UCSD Cancer Center in La Jolla.

Too little sun isn't great either, however, since sunlight helps the skin manufacture healthy vitamin D. "It would be false prudence to stay out of the sun to prevent skin cancer and not get enough vitamin D," Garland said.

Other experts, however, feel the focus should stay on cigarette smoking as the number one cause of lung cancer.

"When you have such a strong factor as tobacco, it really weighs out all these other small influences," said Dr. Jay Brooks, chairman of hematology/oncology at the Ochsner Health System in Baton Rouge, La. "It's a very interesting observation, but the main message is tobacco is such a strong influence in the development of lung cancer that we should concentrate on that."

More than one million people die of lung cancer worldwide each year. Cigarette smoking causes about 85 percent of lung cancers. The remaining cases are caused by exposure to secondhand smoke and a variety of other (some unknown) factors.

Sunshine is a significant source of vitamin D, as the sun's UV rays trigger synthesis of vitamin D in the skin.

Previous research, much of it by the same group, has found a strong association between breast cancer, colon cancer and other internal-organ cancers and living in latitudes with less sunlight. For example, one paper observed double the death rate from colon cancer above the U.S. Mason-Dixon line as below, leading the researchers to focus on lack of sunlight as the culprit.

It wasn't a new idea. "There were people in epidemiology dating back to Hippocrates who thought it was a good idea to live on the south side of a hill," Garland said.

Another study linked lower levels of a vitamin D metabolite in the blood with a higher level of colon cancer.

For this study, Garland and his colleagues looked at the association between latitude and exposure to UVB light and rates of lung cancer in 111 countries. Data came from an extensive United Nations database.

Although smoking showed the strongest association with lung cancer, exposure to UVB light also had an impact.

UVB light is greatest closer to the equator. This study showed that lung cancer rates were highest in regions farthest away from the equator and lowest in those regions nearest to it.

Higher cloud cover and aerosol use (both of which absorb UVB rays) were linked with higher rates of lung cancer.

For men, smoking was associated with higher rates of lung cancer, while greater exposure to sunlight was associated with lower rates.

For women, cigarette smoking, along with total cloud cover and aerosol levels, were associated with higher rates of lung cancer, while sunlight was again associated with lower rates.

Previous research has indicated that vitamin D may be able to stop the growth of malignant tumors.

"Everyone should be taking vitamin D, and, at all latitudes, there's plenty of potential to make vitamin D," Garland said. "Even in Helsinki, people can take advantage of the sun in summer months."

And vitamin D produced in the summer will carry over into the winter. Even so, unless you know what your vitamin D levels are, it might be wise to take a supplement, Garland advised.

More information

For more on vitamin D, head to the U.S. National Institutes of Health.