Are We Ready for Online Tools in Decision Making
for BRCA1/2 Mutation Carriers?
D. Gareth Evans, The University of Manchester, Manchester Academic Health Science Centre, Central Manchester University
Hospitals Foundation Trust, St. Mary’s Hospital; and Genesis Prevention Centre, University Hospital of South Manchester,
Wythenshawe, Manchester, United Kingdom
Anthony Howell, Genesis Prevention Centre, University Hospital of South Manchester, Wythenshawe, Manchester, United
Kingdom
See accompanying article doi: 10.1200/JCO.2011.38.6060
Decision making for female BRCA1/2 mutation carriers regard-
ing when and whether to undergo risk reducing breast and or ovarian
surgery is complex and involves not only the desire to stay alive longer,
but to avoid the diagnosis of breast and ovarian cancer itself. These
considerations are balanced against the desire for most women to have
children, which in modern western society is often at a later age, as well
as the impact of bilateral salpingo-oophorectomy (BSO) in causing
early menopause with its attendant symptoms, increase in heart dis-
ease and osteoporosis risk, and for some women a loss of sexuality and
gender identity.
1-3
Bilateral risk-reducing mastectomy (BRRM) may
have a greater impact psychologically than BSO since it affects body
image. There are large variations in uptake of BRRM,
4
which may
reflect cultural differences, whether the procedure is offered and if so
the way and time at which it is offered
5,6
Decision aids are increasingly
used to help in complex decision making in other areas of breast
cancer management, such as the successful Adjuvant! Online program
(http://www.adjuvantonline.com/index.jsp). Development of deci-
sion aids addressing the complex issues faced by BRCA1 and BRCA2
mutation carriers is to be welcomed.
In the article accompanying this editorial, Kurian et al
7
have
extended their work with a model that predicts tumor incidence and
survival in BRCA1/2 mutation carriers and have developed these data
into a decision aid for female carriers of BRCA1/2 mutations who have
to make complex trade offs between surgery and screening for breast
and ovarian cancer. The model is based on data from the published
literature, but several assumptions have to be made in the absence of
firm data, including penetrance estimates of each gene mutation as a
function of age, as well as survival from each cancer after diagnosis.
There are two major concerns with regard to the validity of the as-
sumptions made to produce the model, which may possibly affect the
accuracy of the decision aid in the clinic.
The first concern is the assumption that the penetrance of BRCA1
and BRCA2 germline mutations does not vary in relation to factors
other than age, such as the degree of family history and other known
risk factors such as age of first pregnancy or body mass index, among
others. The Breast and Ovarian Analysis of Disease Incidence and
Carrier Estimation Algorithm (BOADICEA) model
8
builds estimates
of penetrance of BRCA1 and BRCA2 in relation to age and closeness of
relatives with breast cancer and this could be included in the Kurian et
al
7
model. In addition to some lack of precision based on these issues,
there is also concern that Kurian et al may have underestimated
penetrance since they used estimates for breast cancer from popula-
tion studies
9
that assessed risk in women with birth cohorts consider-
ably earlier than their own modeling for women born in 1980. Breast
cancer incidence has increased markedly both in the general popula-
tion and BRCA carriers as demonstrated so well in Iceland, which
shows a fourfold increase in sporadic breast cancer and in the pen-
etrance of the BRCA2 founder mutation over the 80 year period from
1920 to 2000.
10
Most women who are referred for genetic testing are
identified through reasonably strong family histories, and their pen-
etrance estimates should reflect that.
11,12
This influence of family
history is likely to be partly due to the coinheritance of other lower risk
genetic susceptibility alleles that have been identified in Genome Wide
Association Studies (GWAS).
11
Thus far at least 18 common low risk
genetic susceptibility loci have been identified using frequently occur-
ring single nucleotide polymorphisms (SNPs).
13
Most of these have
now been validated as affecting risk in BRCA2 mutation carriers al-
though only a few for BRCA1.
14-17
Use of just five of these SNPs
modifies the penetrance for breast cancer from between 95% down to
as little as 45%.
17
and this type of information should be considered for
inclusion in future iterations of the Kurian et al model.
Another important issue in determining risk to an individual is
their hormonal and reproductive history. Apart from parity, where the
data are conflicting,
18,19
the remaining risk factors such as age at
menarche, oral contraceptive use, and age at menopause have either
similar effects to those seen in the general population or no effect.
20-22
The greatest single risk factor, mammographic density, also substan-
tially affects breast cancer risk in BRCA1/2 carriers.
23
Clearly addition
of both family history and nongenetic risk factors would make the
algorithm in the decision aid far more complex, but ignoring these
factors altogether will mean that women are given an average risk of
breast and ovarian cancer, whereas in reality many women will have a
substantially different risk from the average BRCA carrier.
Yet another area where the assumptions made by Kurian et al
7
may be problematic is in the calculation of survival. A major concern
is overestimation of survival of BRCA1 carriers with breast cancer
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