Breast cancer in men is rare, and men with breast cancer receive
the same anti-hormonal therapy as women. Often with effect, but
there was no scientific basis for it before now. Cancer
researchers led by Wilbert Zwart from the Netherlands Cancer
Institute and Oncode Institute are now the first to clarify how
hormones affect tumor DNA in men with breast cancer.
Most tumors in men barely differ biologically from those in women.
But in tumors that react badly to anti-hormonal treatment, the
researchers saw subtle differences between the two sexes. These new
insights constitute another major step towards the best customized
treatment for men and women.
The researchers published their findings on February 2 in the
scientific journal Nature Communications.
Therapy based on treatment of women
Approximately 100 men per year are diagnosed with breast
cancer in the Netherlands, compared to more than 14,000 women. In
the vast majority of breast cancers, both in men and women, the
tumor is hormone sensitive. This means that hormones, like
estrogen, influence the DNA, causing the tumor to grow and
eventually to spread. Anti-hormonal therapy, aimed at blocking the
female hormone estrogen, is therefore also often part of the
treatment for men. Often with effect but also with stressful side
effects. However, there was not yet a scientific basis for giving
men the same treatment as women. The researchers, led by Wilbert
Zwart, have now mapped the hormonal function over the entire tumor
DNA for the first time and compared men and women.
Big picture: hardly any biological
The first conclusion was that by far most of the breast tumors in
men and women are barely distinguishable from each other. This
provides a scientific basis for the current practice of giving men
and women the same anti-hormonal therapy.
In tumors with less favorable prognosis, there are
But as with women with hormone-sensitive breast cancer, there are
also men whose cancer still comes back despite the treatment. This
group is therefore likely to benefit from a different or
supplementary approach. And it is precisely in this group of men
that the DNA profiles of the tumor appear to be
Step towards customized treatment
Wilbert Zwart: 'We had already seen that very specific patterns in
women are predictive of the course of the disease. In patients with
a less favorable course of the disease, other sites of the DNA are
active under the influence of hormones. That says something about
the therapy sensitivity of each individual tumor and this knowledge
is essential when looking for a customized therapy. In men, we also
see specific patterns that are different than in women. If we
are to work towards a customized therapy for men, the selection of
medicines may, therefore, have to be slightly different. But a lot
of research is still needed for this.'
'Characterizing steroid hormone receptor chromatin
binding landscapes in male and female breast cancer', Tesa
Severson, Yongsoo Kim, Stacey Joosten…Wilbert Zwart, Nature
Communications February 2, 2018
This research is funded by KWF (Dutch Cancer Society), Alpe
d'HuZes and NWO.
Molecular biologist Wilbert Zwart from the Netherlands Cancer
Institute specializes in hormone-sensitive cancer. He and co-author
Lodewyk Wessels are two of the 43 research
leaders at the new Oncode Institute that was opened by Queen
Máxima on February 5.