Just a Few Hostile Cells Fuel Breast Cancer Growth 

Powerhouse 'factory' cells may be key targets for medications

Breast cancer may contain a tiny minority of aggressive "stem" cells that can give rise to entire new tumors, new research says.

As few as 100 of these cells can allow the tumor to make copies of itself, becoming a factory that makes all the other types of cells in the original tumor, says the study, that appears in a recent issue of the Proceedings of the National Academy of Sciences. Their ability to regenerate is much like that of stem cells, researchers say.

Even tens of thousands of other types of cells in the same tumor did not create more cancer, the study says.

"We're really excited; we're extraordinarily excited," says study author Dr. Michael F. Clarke, a professor of internal medicine at the University of Michigan Medical School. By isolating these cells, they have narrowed the field that therapies may one day target in the overall confusing mix of cells in these tumors, he adds.

Detecting Cells Could Lead to Earlier Diagnosis

Detecting these cells could also lead to a way that will let physicians diagnose the disease sooner, says Clarke. However, even though human cancer tissue was used, the tests were done on mice, so a practical application for their findings is still in the future, although Clarke says their research might be useful for humans within five years.

"We're three steps away [from developing a drug]," Clarke says. Next, researchers will find out what pathways let these cells form tumors, then they will find out where the pathways are and focus on them. The third step is to develop medications to attack these pathways.

More than 40,000 women die of breast cancer each year in the United States and it is the most common type of cancer in women.

Other scientists also see potential in this discovery.

This is "a very intriguing study, which provides molecular identification of particularly aggressive breast cancer cells and which suggests potential new avenues for diagnosis and therapy," says Dr. Calvin Kuo, an assistant professor of medicine at Stanford University.

The Michigan research builds on a previous study that saw a similar effect in a type of leukemia (blood cancer), but this is the first time these "stem" cells have been found in a solid cancer, the researchers say.

Figuring out how to tell the difference between the two kinds of cells took years for Muhammad Al-Hajj, a postdoctoral fellow and a co-author of the study. He and the team took tumor tissue from nine breast cancer patients, and discovered that eight of them had the same protein "fingerprint" on the surface of their cancer cells. The ninth had a biological variation that made the separation of cell types difficult, says Clarke.

In the remaining eight samples, the nasty "stem" cells had a pattern of surface proteins where there was a lot of a type called CD44 and little to none of a type called CD24. The researchers harvested cells showing this pattern and injected them into mice. As few as 100 of these cells caused tumors identical to the original to form, the researchers found.

Since an aggressive subset of cells has been found in both blood and breast cancers, the scientists think other types of cancer might be driven by them, as well.

Always consult your physician for more information.

Tamoxifen Cuts Risk of Benign Breast Disease 

Drug reduces hyperplasia, fibrocystic disease by 28 percent 

Tamoxifen, the drug that has been shown to cut the risk of breast cancer in high-risk women, also appears to reduce the incidence of noncancerous breast disease, new research shows.

An earlier trial, the Breast Cancer Prevention Trial, part of the National Surgical Adjuvant Breast and Bowel Project (NSABP), found that tamoxifen reduced the incidence of invasive and noninvasive breast cancer by up to 50 percent.

In the current trial, reported in a recent issue of the Journal of the National Cancer Institute, the drug reduced the incidence of benign breast disease, including fibrocystic disease and hyperplasia, by 28 percent. It also resulted in fewer biopsies.

Tamoxifen interferes with the activity of the hormone estrogen and is therefore effective in breast cancers that are estrogen-receptor positive. Estrogen receptors are also expressed in benign breast lesions, leading researchers to believe that tamoxifen might also have an effect here.

Benign breast disease can be a risk factor for later breast cancer.

Always consult your physician for more information.

Online Resources

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American Cancer Society

Breast Cancer Prevention Trial

Journal of the National Cancer Institute

National Cancer Institute

National Institutes of Health (NIH)

National Surgical Adjuvant Breast and Bowel Project (NSABP)

Proceedings of the National Academy of Sciences

March 2003

Powerhouse 'Factory' Cells May Be Key Targets for Medications

Detecting Cells Could Lead to Earlier Diagnosis

Tamoxifen Cuts Risk of Benign Breast Disease 

Younger Women With Family History Skip Mammograms  

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In Other Breast Health News:

Younger Women With Family History Skip Mammograms 

New research says fear may be the key factor 

Younger women with a family history of breast cancer are less likely than others to get regular mammograms.

That is the surprising finding of a new study that evaluated almost 30,000 women.

While the study showed that educated Caucasian women with higher incomes and insurance coverage are the most likely to get routine breast-cancer screenings, it also showed that women in their 40s with a family history of the disease were less likely to do so.

The reason, says the study's author, could well be fear.

"Fear may have a negative impact. People are more afraid of being diagnosed [if they have a family member with breast cancer]. There is kind of a denial situation," says Dr. Saleh Rahman, an assistant professor of public health at Bowling Green State University, whose findings were presented at the recent Preventive Medicine 2003 meeting in San Diego.

For the study, Rahman evaluated the records of 27,778 women, aged 40 to 90, who were entered into the database of the Colorado Mammography Project. Rahman and his colleagues conducted the analysis from 1994 to 1998, looking at race, educational level, income, insurance status, and family history to see which factors predicted how women adhere to the screening recommendations.

Overall, 41.4 percent got a mammogram as recommended, Rahman says. That is an improvement from earlier years, he adds, noting that a 1987 government survey found only 30 percent got a mammogram as advised. In Rahman's study, women who were more highly educated, with higher incomes and insurance coverage, were most likely to get regular mammograms.

Older women were more likely to get regular mammograms than the younger women in general, he also found.

Rahman had predicted some factors would influence whether women got mammograms, such as ethnicity, education, age, and income, but he had not thought that family history would decrease the likelihood.

"We need to develop behavioral interventions addressing these factors to neutralize those fears," he says.

The new study findings are at odds with some other research, says Debbie Saslow, director of breast and gynecologic cancers for the American Cancer Society.

"I'm glad they did the study," Saslow adds, "[but] I was a bit surprised [by some of the findings."

"We've seen a lot of national statistics that show black and white women are getting mammograms at equal rates," Saslow says. "Perhaps this study has found regional differences or localized differences. Or it could be things have changed since the analysis was done."

Overall, research on whether women with a family history of breast cancer get regular mammograms or skip them has been mixed, Saslow says: "Some go into denial, some adhere."

In the Rahman study, the younger women were less likely to get a mammogram. In years past, Saslow says, there used to be a difference in adherence between younger and older women, with women over age 65 less likely to get mammograms. "Now that difference is going away," she says.

The American Cancer Society recommends that all women age 40 and older have annual mammograms. This year, an estimated 211,300 new cases of invasive breast cancer are expected to occur among women in the United States, and 55,700 new cases of localized breast cancer are expected to be diagnosed. More than 40,000 deaths from breast cancer are expected in 2003.

Always consult your physician for more information.