TUESDAY, Sept. 30 (HealthDay News) -- Researchers have uncovered a genetic link between obesity and the risk for colon cancer. The discovery could lead to greater accuracy in predicting who is at risk for the disease, experts say.

Research has suggested that colon cancer risk rises with increasing weight, but this finding points to a genetic reason for the link.

"We have discovered that a genetic variant of the adiponectin gene, called ADIPOQ, is associated with colon cancer risk," said lead researcher Dr. Boris Pasche, director of the division of hematology and oncology at the Comprehensive Cancer Center of the University of Alabama at Birmingham. "This genetic variant may identify individuals who have a higher risk to develop colorectal cancer," he said.

The report was published in the Oct. 1 issue of the Journal of the American Medical Association.

For the study, Pasche's team focused on ADIPOQ. This gene promotes the formation of a fat hormone called adiponectin. People who inherit a common variant of the gene have up to a 30 percent lower risk of colon cancer compared with people without this gene variant, the study found.

On the other hand, the researchers believe that people who do not have this gene variant, or those who have high levels of adiponectin in their blood, may be at a slightly increased risk for colon cancer and could benefit from early screening for the disease.

"Adiponectin, a hormone exclusively secreted by the adipose [fat] tissue, is now genetically linked with colorectal cancer," Pasche said. "This is the first evidence that genetic variants of a 'fat hormone' affect risk of colorectal cancer," he said.

Whether people without this gene variant can reduce their risk of colon cancer through diet and exercise isn't clear, the researchers noted.

"This adds a little bit more to our understanding of one place where genetics plays a role in colon cancer development," said Dr. Durado Brooks, director of colon and prostate cancer prevention programs at the American Cancer Society. "It helps point us in some more specific directions; it adds another piece to the puzzle," he said.

Brooks does not believe that the finding is definitive, however. "It supports some of the other work that has already been done, identifying this particular gene region with colorectal cancer," he said.

The finding does help clarify one element linking obesity and colon cancer, but "there is no clinical application to this finding in the immediate future," Brooks said. "I don't think we would alter any recommendation, other than encouraging people to maintain a healthy weight."

Dr. Georgia Wiesner, a cancer geneticist at University Hospitals' Case Medical Center in Cleveland, agreed.

"I'd love to say that any time we find a new gene that identifies risk or alters risk we would be able to put that into a new drug treatment or at least identify people who are more at risk," Wiesner said. "But in this study, it might just tease out the pathogenesis of disease," she said.

It's already known that people who are obese have a higher risk for colon cancer, Wiesner said. "I don't know that telling somebody they might have a specific marker is really going to alter what they are going to do," she said. "It doesn't mean that these people don't need regular screening."

More information

For more on colon cancer, visit the American Cancer Society  .

TUESDAY, Sept. 30 (HealthDay News) -- Women who are heavier and longer at birth are at increased risk of developing breast cancer later in life, British researchers report.

In fact, as birth weight and length increases, so does the risk for breast cancer, according to the results of a study published in the Sept. 30 online edition of PLoS Medicine.

"These researchers have documented in unequivocal terms that larger birth size is associated with increased breast cancer risk several decades later," said Dr. Dimitrios Trichopoulos, the Vincent L. Gregory Professor of Cancer Prevention at Harvard University School of Public Health Department of Epidemiology and author of an accompanying journal editorial.

Birth size reflects, to a considerable extent, the effects of the intrauterine environment on the fetus, Trichopoulos noted. "To this day, they had not been sufficiently appreciated by the scientific community, because each individual study could not provide conclusive evidence. We are facing now a new reality: that breast cancer has its origins several decades before its clinical appearance," he said.

For the study, a research team led by Dr. Isabel dos Santos Silva, a professor of epidemiology at the London School of Hygiene and Tropical Medicine, collected data on more than 600,000 women, 22,058 of whom had breast cancer. The data came from 32 studies.

The researchers found that women who were heavier and longer at birth had increased risk for breast cancer as adults. An analysis of birth records, among these women, found that for every 17.6 ounces of birth weight, the risk for breast cancer increased 7 percent.

In addition, birth length and head circumference were also associated with an increased risk of breast cancer. The strongest association between size at birth and an increased risk for breast cancer was seen for birth length, the researchers reported.

"Recognition of early life influences are critical in the etiology of breast cancer and helps to explain why several adult life primary prevention practices -- as distinct to secondary prevention ones focusing on early detection -- have been of limited effectiveness," Trichopoulos said.

"Prevention of breast cancer needs to take into account the very long natural history of the disease," he added.

Expert reaction to the new research was fairly guarded.

"There's good evidence for these findings, but there is really no clinical relevance for them," said Debbie Saslow, director of breast and gynecologic cancer at the American Cancer Society.

"There is nothing that women should do differently to try to have smaller babies, or women who were born with a longer length or larger head circumference should do anything differently when they grow up or get screened differently, or consider themselves at high risk -- it's really just a research issue," Saslow said.

More information

For more on breast cancer, visit the American Cancer Society  .

MONDAY, Sept. 29 (HealthDay News) -- Cancer patients often turn to the Internet as a source of information and hope. But all too often, those hopes are betrayed by purveyors of so-called cancer "cures" that are anything but, experts say.

Earlier this month, five companies were charged with making false and misleading claims for cancer cures, and settlements were reached with six other companies, the U.S. Federal Trade Commission announced. Products marketed by the companies included essiac teas and other herbal mixtures, laetrile, black salve (a corrosive ointment), and mushroom extracts.

"There is no credible scientific evidence that any of the products marketed by these companies can prevent, cure, or treat cancer of any kind," said Lydia Parnes, director of the FTC's bureau of consumer protection, the Associated Press reported.

In June, the U.S. Food and Drug Administration issued warning letters to two dozen companies peddling everything from cure-all teas to tablets and tonics. And earlier this year, more than 100 manufacturers of such products were issued similar letters.

According to the American Institute for Cancer Research, black salves are one of the most dangerous of these fake cures. The products, which supposedly "draw out" the disease from under the skin, can actually burn the skin and cause scarring.

Which is not to say that none of these compounds has potential as cancer fighters. But consumers need to be careful.

"Many of these compounds touted as having beneficial effects have lots of lab research, but it's more selling hope in a jar based on preliminary lab research," said Sarah Wally, a nutritionist with the American Institute for Cancer Research in Washington, D.C. "That's not fair to the consumer, particularly consumers with cancer who have a really strong motivation to try anything that might offer hope."

Many of these so-called cures or preventive treatments won't actually cause harm (except to your wallet), but some can interact with regular, supervised medical treatment, Wally said.

"Antioxidants can actually interfere with chemotherapy and radiation treatment," she said. "Some people think, 'I'm just drinking juice.' But they might be drinking two gallons of juice a day of super-antioxidant juice compound, not thinking to discuss it with their doctor."

And, some consumers may actually forego lifesaving conventional treatments in favor of shams.

Here's some advice from the experts:

• "If it sounds too good to be true, it probably is," said Dr. Ted Gansler, director of medical content for the American Cancer Society. Beware of claims that one treatment will cure all types of cancer or more than one type of disease. Also be leery of language such as "scientific breakthrough," "miraculous cure," "secret ingredient" and "ancient remedy," as well as claims that a product is "natural" and therefore safe. And take note of claims that the product has limited availability and that the company needs advance payment.
• Find out if the product has ever been tested in humans. Laboratory and animal research is fine, but only as a starting point, not as a basis for recommending the therapy in humans, Wally said.
• "Be careful about the credentials of the people promoting the treatment," Gansler said. "The possibility that someone with no medical or scientific treatment is going to come up with a cure for cancer or other diseases is not very likely." Reliable sources of information include the American Cancer Society, Memorial Sloan-Kettering Cancer Center in New York City, and the University of Texas M.D. Anderson Cancer Center. (All have Web sites.)
• "Watch out for evidence that is only testimonial," Gansler said. "In some of the most notorious alternative clinics, people will be diagnosed with cancer who don't even have cancer and, later on, they're 'cured.' " The "patient" may actually believe he or she was cured.
• Be on the lookout for obvious factual errors. If someone says their "Stage 7" cancer has been cured, be leery. There is no "Stage 7" cancer.
• Wally advised: "Before you wholeheartedly jump into these things, you need to really sit down and have a discussion with your physician." This is especially true in an age when alternative and complementary medicines are gaining acceptance. It can be tricky distinguishing between something bogus and something that may have a benefit, Wally added.

More information

The FDA has more on fake cancer cures to be avoided.

MONDAY, Sept. 29 (HealthDay News) -- Cancers typically spread -- or metastasize -- to specific, predictable locations. Now researchers have a deeper molecular understanding of why, at least for lung metastases in mice.

The finding might someday lead to drug therapies that curb lung cancer metastasis in humans, experts say.

Dr. Yoshiro Maru of the Tokyo Women's Medical University and colleagues report that primary tumors transmit a series of signals throughout the body to "prepare the soil" in the lungs to accept the "seed" of a metastatic cell from solid tumors located elsewhere.

The key players in this process are signaling proteins, which pass back and forth like text messages between the tumor and the premetastatic lung, and then from the premetastatic lung to the tumor and the bone marrow.

"I think the important part of the paper is that it's putting molecules on these pathways between different cells ... and between the primary tumor and the soil," said Mikala Egeblad, an assistant research anatomist at the University of California, San Francisco.

Just as important, the new study suggests that blocking these signaling interactions could inhibit the ability of tumors to metastasize to the lungs.

The findings were published online Sept. 28 in the journal Nature Cell Biology.

According to Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, much has been learned about what differentiates a benign growth from a more aggressive cancer, as well as the characteristics of cells that break off from a primary tumor and make their way to distant sites within the body -- that is, to metastasize. This study, however, examines how a tumor is able to colonize a particular tissue -- in this case, the lungs.

"This research takes a look at what allows the cancer cells to set up a home in the lungs of the mice," Lichtenfeld said. "By understanding that mechanism, they potentially could incorporate that theory into the treatment of patients and perhaps, by understanding those mechanisms, you may be able to take advantage of that to prevent that [metastasis] from happening."

Studying lung metastases in mice, Maru and his team investigated the cellular signals that accompany tumor migration to the lung. What they discovered was a sort of signaling cascade -- a series of protein messages flashing back and forth throughout the body.

According to their theory: Suppose a tumor in the colon or breast is preparing to metastasize. Before it does so, it sends out specific proteins called growth factors throughout the body.

In cancer-free lungs, local cells respond by producing a second signal: a pair of molecules called S100A8 and S100A9. Nearby lung monocytes respond to these messages by producing the third and final message, called SAA3. This causes immune cells called macrophages to amplify the signal even further, driving both immune cells and tumor cells to migrate to the lungs.

Both of those cell types express the receptor for SAA3 -- a protein called TLR4. According to Maru, "that's a big problem," because TLR4, in a healthier context, induces immune cells to get on the move. But in this case deadly cancer cells get moving, too.

In this way, "the tumor prepares the soil, the pre-metastatic site, prior to its settlement," Maru said.

According to Egeblad, this study suggests "how the tumor is preparing organs, and particularly lungs, so that when the cancer cells arrive, they have an easier time staying and growing."

Added Lichtenfeld, "If they can interfere with that mechanism, they can prevent that [metastasis] from happening, and this could then become an important part of cancer treatment in the future."

More information

For more on lung cancer, visit the U.S. National Cancer Institute.