Sexual assault and breast cancer: is there a link?

There’s a hashtag trending on Twitter today, #metoo, started by actor Alyssa Milano. The goal was to continue to raise awareness of sexual assault and harassment in U.S. culture, which should be considered epidemic: 300,000 Americans (one person every two minutes) are sexually victimized each year.

Research suggests that sexual assault has long-term impacts on health, its impact reaches far beyond the immediate violation.

Almost 20 years ago, scientists first reported on the long-lasting effects of sexual assault. A survey of 1,300 elderly white, middle class study participants from a Southern California community revealed that 12% of the women and 5% of the men had been victims of  sexual abuse at an early age.

Past sexual assault was associated with an increased risk of breast cancer, arthritis and thyroid disease, [Murray B.] Stein and [Elizabeth] Barrett-Connor found. The study results appear in the November/December [2000] issue of Psychosomatic Medicine.

Multiple abuse episodes increased the risk of breast cancer by two- to three-fold compared with a single episode of abuse.

A Canadian study from 2009 found “a significant and highly stable association between childhood physical abuse and cancer,” which is a broader definition of abuse.

This research built upon prior examination of childhood maltreatment and its association with “adult chronic health conditions, including heart disease, functional somatic syndromes, diabetes, arthritis, asthma, and bronchitis/emphysema.”

Also in 2009, researchers determined that women in the U.S. military had a significantly higher rates of breast cancers than their civilian analogues. Black military women had a significantly higher rate of cervical cancer. Whether this increase is due to stress or other factors, such as screening, chemical exposure, or oral contraceptive use is unknown.

In 2011, researchers focused on 35,728 participants in the Black Women’s Health Study:

The present study of African-American women shows a positive relation between physical abuse victimization in adulthood and breast cancer incidence, but no evidence of a dose–response relation. No associations with breast cancer were found for abuse occurring in either childhood or adolescence. These findings require confirmation in future studies.

In 2012, researchers determined that early life sexual and physical abuse was associated with an increased risk of adult obesity in participants in the Black Women’s Health Study. Obesity is a risk factor for breast cancer for women after menopause.

In 2016, researchers at the University of Copenhagen determined that survivors of sexual assault were at greater risk for circulatory and respiratory diseases, epilepsy, liver disease, and cervical cancer.

The emotional toll of sexual violence can lead to PTSD; chronic fear can weaken the immune system and lead to inflammation, which increases cancer risk.

The gift that keeps on giving

Trauma can be passed on to later generations, altering how  DNA is expressed without changing its sequencing. This is called epigenetic inheritance; what changes is the chemical marker for the gene, not the gene itself. The landmark paper, “Epigenetic programming by maternal behavior,” was published in June 2004 in the journal Nature Neuroscience.

Epigenetic inheritance was later again shown with mice, but there’s resistance to the idea that this might be true with humans.

In 2015, researchers at New York’s Mount Sinai Hospital focused on Holocaust survivors and their descendants and provided the first proof of epigenetic influence in people.

“The gene changes in the children could only be attributed to Holocaust exposure in the parents,” said [Rachel] Yehuda… “To our knowledge, this provides the first demonstration of transmission of pre-conception stress effects resulting in epigenetic changes in both the exposed parents and their offspring in humans.”



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