Hardly a day goes by without the media excitedly reporting on another “breakthrough” in the detection and treatment of breast cancer. And while there certainly is a great deal of research activity going on, it seems that it rarely connects with women’s everyday lives. In fact, it’s more often than not downright confusing, with a number of studies contradicting one another.

A recent study conducted by the Danish National Institute of Public Health (DNIPH), into the relationship between stress levels and breast cancer, is one example that’s more likely to confuse than inform. The study, published in the British Medical Journal, shows that stress can actually decrease a woman’s risk of developing breast cancer. But women have previously been warned that high levels of stress - such as traumatic life events - can lead to adverse effects that can actually be the catalyst for breast cancer and other serious diseases.

Another recent study claims that mammograms are a waste of time, and do little to reduce breast cancer mortality rates. Confused? So are we. But don’t let these contradictory findings get you stressed!

Women have been made aware of the link between high levels of stress and breast cancer (hmm, I wonder if this is just a male conspiracy to keep us out of those high powered executive positions) for some time so the new Danish study that contradicts these earlier findings is worthy of further examination.

Naja Rod Nielsen, the lead researcher for the Danish study, asked women only two very general questions for the study that related to how intensely and how frequently women experienced feelings of stress in their everyday lives. In the early 80s, over 6,000 women were asked these questions and then subsequently monitored for 18 years. Nielsen said that although this approach to gauging stress levels seems very broad, it is an accepted methodology. “A lot of people use a global measure of stress, it’s not a validated scale but it’s used widely around the world,” explained Nielsen.

So, what did Nielsen’s team find after 18 years? “We found that women who reported high levels of stress in their daily life were actually 40 percent less likely to develop a first time breast cancer during follow up compared to women who reported no stress at base line,” said Nielsen. After all the findings about the link between stress and breast cancer that previous studies had suggested, this contradictory finding initially seemed very odd to Nielsen. That was until Nielsen reviewed the literature and found something very interesting.

The research team found that: “prolonged activation of stress hormones seems to lead to a lower production of estrogen which is one of the main risk factors for breast cancer,” explained Nielsen. This, says Nielsen, is a possible biological explanation for high levels of stress and a decreased risk of breast cancer, which, if true, would be very significant. Supporting this finding even further, it has been known for some time that estrogen levels are linked to breast cancer. But before everyone rushes off in search of a stress-filled life there are some other factors that need to be considered.

While the biological link between estrogen and breast cancer has yet to be tested on humans, this is not the main criticism leveled at Nielsen’s research. The fundamental weakness is its reliance on the subjects’ “self-monitoring” of stress levels during the 18 year period. Put simply, my low stress level may be your high stress level. Nielsen is conducting further research into stress levels, but remains tight-lipped in regard to any preliminary findings, as the research is yet to be completed. Who knows, perhaps we’re in for more surprises.

In another article in the British Medical Journal, researchers claimed that breast cancer screening in “real world” situations is not effective in saving lives. The study, published in the Journal of the National Cancer Institute, contradicts long held beliefs that breast cancer screening prevents deaths among the 40 or older age group. The study’s lead author, Joann Elmore, at the University of Washington School of Medicine, said: “We observed no appreciable association between breast cancer mortality and screening history, (regardless of age or risk level).” Initially the team expected to find that women who were screened regularly would have a lower mortality rate than those women who were not screened as often. But the researchers reported being surprised that even considering factors such as age and risk level, the mortality rate was only 26 percent lower among women who underwent regular screening.

Elmore’s findings contradict another similar study conducted in Copenhagen, where a research team compared mortality rates before and after the introduction of mammography screening in 1991. In the study, the team found that 10 years after the introduction of a mammography screening program in Copenhagen there was a 25 percent drop in mortality rates, which they considered significant.

It does seem odd that one research group can find a 25 percent measurement significant while another finds it insignificant.

Making any sense of all the booby-babble emerging from breast cancer research is difficult given that it can sometimes seem contradictory and confusing. And while it’s helpful to apprise oneself of the latest research findings, it’s common-sense to pay heed to the current medical consensus, which recommends regular screenings. And as for stress levels, who knows? Perhaps further research will shed some light on whether stress can be beneficial in modulating estrogen levels. Until then, don’t get stressed over your stress levels!

Based on:

“Stress and Breast Cancer”: http://www.abc.net.au/rn/talks/8.30/helthrpt/stories/s1456755.htm

“Self Reported Stress and Risk of Breast Cancer”
British Medical Journal, doi:10.1136/bmj.38547.638183.06

“Study says breast cancer screening does not save lives”
British Medical Journal, doi:10.1136/bmj.331.7512.309 BMJ 2005;331;309- Janice Hopkins Tanne