Breast cancer: birthmarks provide clues

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MunichHow many moles a woman has could be an indicator of her risk of developing breast cancer. Because both seem to be influenced by the same hormones, American researchers report.

Is there a relationship between the number of birthmarks and the risk of breast cancer? Mingfeng Zhang and colleagues from Brigham and Women's Hospital and Harvard Medical School (Boston) investigated this question using data from over 74,000 women as a basis. In addition, the participants stated how many moles over 3 millimeters they had on their left arm 5,400 of the women developed breast cancer over a 24-year period.

More than 15 moles on the arm

The study found that women with 15 or more moles were 35 percent more likely to be diagnosed with breast cancer - at least when compared to women who had no skin pigmentation. Overall, the researchers put the probability of breast cancer in women without moles in general at 8.48 percent - in women with more than 15 birthmarks, however, at 11.4 percent.

Hormones affect moles

The scientists suspected that hormones were to blame for this connection. It has long been known that, for example, the texture of moles changes when women are pregnant and large amounts of hormones flood through their bodies. Then the birthmarks often enlarge and darken. Now it became clear that the postmenopausal women who had more than six birthmarks on their arms actually had higher levels of estrogens and testosterone in their blood.

The association between breast cancer and the number of liver spots persisted even when other risk factors for the tumors were included. However, when the researchers adjusted their data for the hormone levels, the link between breast cancer and the number of birthmarks disappeared. "We have thus identified the number of birthmarks as a possible marker that can indicate the risk of breast cancer," the researchers conclude. However, the researchers were unable to clarify exactly how the sex hormones affect the development of the moles.

Risk factor hormones

Estrogens are hormones with many properties. They control almost all processes in the female cycle and in reproduction. Without it, nothing works in women's bodies. On the other hand, the same group of hormones is a risk factor for breast cancer. The following applies: the longer the female sex hormones act on the breast tissue, the greater the risk of disease seems to be. (lh)

Source: Zhang M. et al .: Association between Cutaneous Nevi and Breast Cancer in the Nurses "Health Study: A Prospective Cohort Study; PLOS Medicine; DOI: 10.1371 / journal.pmed.1001659

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