Cancer risk clues found in breast milk.

Breast milk may provide a rich amount of genetic data indicating whether or not a woman is at risk for breast cancer.

Kathleen Arcaro, an Environmental Toxicologist at the University of Amherst, analyzed milk from 250 women who had gone through a single breast biopsy to determine whether a lump was cancerous or benign. The researchers tested three genes in a specific type of breast cell that shed in milk for methylation, a chemical modification that can inactivate a gene by disabling its start switch. They found that 13 women who did have cancer had substantially more methylation in a tumor-suppressor gene called RASSF1 than cells from patients with noncancerous breasts. In women whose biopsy result did not show cancer, methylation of another tumor suppressor gene, SFRP1, was more common in milk from the biopsied breast than the other one.

This screening technique is still in its early stages of development, but if enough genes show a significant effect, these screenings could cover a large portion of women, since researchers estimate about 80 percent of women will give birth at some point in their lives. The researchers have not yet figured out the exact method of the test.

David Sidransky, an oncologist at the Johns Hopkins Medical Institutions, believes that breast milk can be an excellent source of genetic information because it is so easily accessible.

(Source: American Association for Cancer Research Meeting, April 4, 2011.)