Breast cancer updates

By Dr. Ananya Mandal, MDApr 5 2011

Breast cancer clues in breast milk

According to the latest research human breast milk holds the potential to assess a woman’s risk of developing breast cancer.

Kathleen Arcaro, an associate professor of environmental toxicology at the University of Massachusetts in Amherst, working on this, collected milk samples from both breasts of about 250 nursing women who had a previous breast biopsy or were scheduled to have a lump biopsied. In most cases the lumps were found to be benign, although cancer was found in 13 women.

The team isolated what are known as epithelial cells from the milk and then looked at the DNA inside them. Certain genes in some of the samples showed changes, which are known as methylation, that are thought to precede the development of cancer. A previous study conducted by Dr. Arcaro using breast milk from healthy women showed few changes in the DNA of certain genes. This study focused on changes in 12 genes that other researchers have shown are involved in the development of breast cancer. The investigators evaluated three genes - RASSF1, GSTP1, and SFRP1

One of the genes is called RASSF1, which is a tumor-suppressing gene. When working properly, that gene helps keep healthy cells from turning into cancer. But when substances or chemicals in the body attach themselves to the gene, or become methylated, the gene malfunctions and may raise the risk of cancer.

Results from this study showed that of the 182 women in the study who had a lump that wasn't cancerous, there were few changes seen in the RASSF1 gene taken from the milk of the biopsied breast compared to the non-biopsied breast as measured by a methylation score. But among the 13 women who had cancer, there was a significant increase in average methylation score for the RASSF1 gene taken from the milk of the biopsied breast compared to the non-biopsied breast. There was also a marginally higher score for another tumor-suppressing gene SFRP1 among the biopsied breasts compared to the non-biopsied breasts among women in the study.

The study was presented Monday at the American Association of Cancer Research's annual meeting, held April 2 to 6 in Orlando, Fla. Dr. Arcaro said the findings prove the concept that the cells in breast milk can be used to assess breast-cancer risk, although much more work needs to be done before a test is actually developed. The study is being funded by the Department of Defense and the Avon Foundation. Dr. Arcaro revealed that the next step would be to recruit another 250 women into the study. She stressed that such a test wouldn't replace conventional screening methods like a mammogram, but that it could signal which women are at the highest risk for later developing cancer and should start screening earlier.

Smoking & breast cancer

Another new study has shown that there is a significant link between smoking and breast cancer risk in postmenopausal women but it depends on their body weight. Breast cancer risk was higher than normal among female smokers who were not obese, but this strong association was not evident in obese female smokers.

The researchers looked at data from 76,628 women, aged 50 to 79, who had no previous history of cancer. They were participants in the Women's Health Initiative study and were recruited between 1993 and 1998 and followed until 2009.

It was seen that non-obese smokers with a body-mass index (BMI) of less than 30 had a significantly increased risk of cancer compared to non-smokers. Those who smoked for 10 to 29 years had a 16 percent higher risk, those who smoked for 30 to 49 years had a 25 percent increased risk, and those who smoked for 50 years or more had a 62 percent greater risk. But obese women who smoked didn't appear to be at increased risk for breast cancer.

The study is slated to be presented Sunday at the American Association for Cancer Research (AACR) annual meeting, in Orlando, Fla.

Juhua Luo, an assistant professor in the department of community medicine at West Virginia University said, “We found an association between smoking and breast cancer risk among non-obese women, which is understandable because tobacco is known carcinogen. However, we did not find the same association between smoking and breast cancer risk among obese women. This result was surprising.” She warned against taking the results otherwise and emphasized that previous research has shown that obesity alone is a risk factor for breast cancer in postmenopausal women. “This is only the first study to examine the interaction between smoking, obesity and breast cancer risk. The main conclusion from this research is that more studies are needed to confirm these results,” Luo said.