For women suffering from the unpleasant physical signs of menopause, here’s some good news: having these symptoms, especially hot flashes, is strongly tied to a reduced risk for certain types of breast cancer, according to a recent study. It’s all in the hormones.

The authors had suspected that because fluctuations in hormones like estrogen and progesterone are largely responsible for the symptoms of menopause and for the development of certain breast cancers, that there would be connection between a woman having the symptoms and her breast cancer risk. To test this, the research team interviewed over 1,400 postmenopausal women, about two-thirds of whom had been diagnosed and treated for breast cancer.

'Women who experienced more intense hot flushes – the kind that woke them up at night – had a particularly low risk of breast cancer.'

All women were asked about their menopause symptoms, from physical symptoms like hot flashes and vaginal dryness to behavioral symptoms like anxiety, depression, and insomnia. Women who reported having hot flashes were also asked to give details about the severity and frequency of them.

The researchers found that there was indeed a strong link between whether or not a woman experienced menopausal symptoms and her risk of breast cancer. Women who had experienced symptoms had between 40 and 60% reduced risk of developing the two most common forms of breast cancer, invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC).

Women with symptoms also had a 70% reduced risk for developing invasive ductal-lobular carcinoma (IDLC), though this finding was non-significant (meaning that it theoretically could have been due to chance). The risks for developing ILC and IDLC were reduced as the number of symptoms increased (this was not true for IDC, however).

Women who experienced hot flashes had an especially reduced risk of breasted cancer, compared to women who only experienced other symptoms. According to lead author Christopher I. Li, "Women who experienced more intense hot flushes – the kind that woke them up at night – had a particularly low risk of breast cancer." Again, the researchers suggest that changing hormone levels (estrogen and progesterone) are at least in part responsible for the symptoms of menopause and the reduced risk of breast cancer.

Even if there is an upside to the unpleasant symptoms of menopause, women who do not experience symptoms should not worry too much. Not having them is in no way a definite marker for breast cancer. More research will be needed to determine whether menopause symptoms and/or hormone levels may be used in the future to help doctors understand a woman’s risk for breast cancer.

Li is affiliated with the University of Washington and the Fred Hutchinson Cancer Research Center. The paper was published in the January 6, 2011 online issue of Cancer Epidemiology, Biomarkers and Prevention.

Woman's Day's blog, Daily Dose has a February 9 guest post by TheDoctor on this study as well.