Please supply source when quoting statistics.

Hi Marg,

Thank you for posting. You may find some more helpful information on the main Breastcancer.org site's page on Understanding Breast Cancer Risk. There's also some good information on Breast Cancer Risk Factors, which lists risk factors you can and can't change.

We hope this helps!

--The Mods

This is misleading. The 5 - 10% genetic percentage that's thrown around is from KNOWN genetic factors, when we've really only just begun our understanding of genetic causes of cancer. I'm also a person who did everything right and got BC. Whenever I would give my kids cruciferous vegetables to eat (my favorite, so I would serve them often) I would always remind them that these types of vegetables are great cancer fighters, to encourage them to eat more of them. Ironic!

According to the 90% statistic - we are all living in a toxic environment, so that means the blame is on us yet again for our EXTREME lifestyles. I'd like to know how the rest of the non-breast cancer peoples' life style is? That slide is almost purposely misleading and should be taken down.

Other members have previously taken issue with this 90% statistic before to no avail per Beesie's post above.

In their reply above, the Moderators cited to text from the Main Site (also without any supporting citation) for the proposition that:

"About 5% to 10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child." (I'd like to know exactly which genes are included in that 10% estimate and what studies established this 10% estimate.)

So, the rest are necessarily due to lifestyle and environmental factors? I don't think that follows. This 90% statistic seems to be a simplistic and inappropriate extrapolation from the proportion of breast cancers (10%) that can be attributed to some (unidentified) subset of known cancer predisposition genes which show single gene, autosomal dominant inheritance patterns (presumably genes such as BRCA1 and BRCA2, and possilby others such as PTEN, CHEK2, ATM?).

If that is how this 90% estimate was derived, please note that it is not scientifically sound to extrapolate from that 10% statistic to conclude that all remaining breast cancers should be attributed to lifestyle or the environment. One reason is that it is acknowledged that there are other, as yet unidentified, heritable cancer predisposition genes beyond those included in current multi-gene panels, and that these unknown genes may confer increased risk either alone (single gene traits) or in combination (polygenic factors). Changes in other genes that confer lower increases in risk and may affect risk cumulatively, are not as easy to identify, but that doesn't mean that they don't exist.

For example, BC.org just featured the results of two recent studies (Michailidou (2017) and (Milne (2017)) identifying genetic variation at new heritable breast cancer risk loci. Reference to "new loci" implies that the genetic location of these changes is distinct from that of previously identified cancer predisposition genes. The results suggest that genetic changes at these loci confer increased risk and may explain breast cancers over and above the 10% of cases attributable to the previously identified genes. Discussing the implications of these studies in a CNN article:

>>> "Lisa Schlager, vice president of community affairs & public policy for the nonprofit FORCE(Facing Our Risk of Cancer Empowered), said past studies and evidence indicate that about 10% of breast cancers are hereditary.

"This new information may mean that that estimate is low," said Schlager.<<<

In addition, some risk factors, such as mammographic density, "will themselves be influenced by genetic factors" as explained by Antoniou (2006):

>>>"A number of risk factors other than family history have been implicated in the development of breast cancer. Some of these risk factors will themselves be influenced by genetic factors, and studying these factors may provide clues to underlying models of susceptibility and lead to the identification of further susceptibility genes (Hopper and Carlin, 1992). Mammographic density is perhaps the most important such risk factor. Mammographic density is strongly predictive of breast cancer risk in the general population (Boyd et al., 1995; Byrne et al., 1995; Harvey and Bovbjerg, 2004), with relative risks of four- to six-fold associated with the highest category of breast density compared with the lowest. Twin studies have demonstrated that mammographic density has a strong genetic component (Boyd et al., 2002; Stone et al., 2006), and it has also been reported that first-degree relatives of women with increased mammographic density are at higher risk of developing breast cancer (Ziv et al., 2003). Such findings provide evidence that breast cancer and mammographic density are likely to have a common genetic basis. It has been estimated that genetic factors that influence mammographic density may explain between 5 and 8% of the observed excess risk of breast cancer among first-degree relatives (Boyd et al., 2005). More recently, it has also been demonstrated that breast cancer risk is associated with density in BRCA1 and BRCA2 carriers (Mitchell et al., 2006), in line with the findings that high mammographic density is associated with the risk of developing both oestrogen receptor (ER)-positive and ER-negative breast cancer (Ziv et al., 2004). Mammographic density is not, however, higher in BRCA1 or BRCA2 carriers, indicating that genes influencing density act independently of BRCA1/2 mutation status. A number of candidate gene studies for mammographic density have been performed, but no genes have been implicated with certainty (e.g. Hong et al., 2004; Mulhall et al., 2005; van Duijnhoven et al., 2005). Segregation analyses of mammographic density have provided some evidence for a major gene component, but have not been able to distinguish between various models of susceptibility (Pankow et al., 1997). . . "<<<

BarredOwl

In addition to the excellent points raised above, I'd like to point out that the wording seems to imply that environmental factors (unspecified on the slide) are as readily subject to modification as lifestyle factors may be.

That fails to account for the possibility of earlier, unknown, exposure to carcinogens or other problematical factors as well as the difficulty of controlling many aspects of our environments. As children, most of us had no control over our environment.

In addition, young women can't choose to delay their age at menstruation. No one has any control over their breast density. Nor can women necessarily conceive and nurse prior to age 30. Many women do not do so at any age whether by choice, necessity or other circumstances. To label the latter two "lifestyle choices" seems to cast a pretty wide and misleading net. Most people, when they think of lifestyle factors think of those listed - exercise, weight control, avoiding alcohol, not childbearing questions.

Since the slide implies that women have a great deal of influence over their chances of experiencing breast cancer I think these are important concerns that are simply buried in the simplistic wording of the slide to the disservice of anyone who reads and relies on it.