Breast cancer in men is rare and men with breast cancer receive the same anti-hormonal therapy as women. Often effective, but there was no scientific basis for this yet. Cancer researchers led by Wilbert Zwart from the Antoni van Leeuwenhoek and Oncode Institute have now clarified how hormones affect tumour DNA in men with breast cancer.

Most tumours in men appear to hardly differ biologically from those in women. But the researchers did see subtle differences between the two genders in tumours which respond poorly to anti-hormonal treatment. These new insights represent another major step towards the best tailor-made treatment for men and women.

The researchers published their findings on 2 February in the scientific journal Nature Communications 

Therapy based on the treatment of women

Around 100 men are diagnosed with breast cancer each year in the Netherlands, compared to more than 14,000 women. In the vast majority of breast cancer cases, both men and women, the tumour is hormone sensitive. This means hormones, such as oestrogen, exert influence on the DNA, causing the tumour to grow and eventually start to spread. That’s why anti-hormonal therapy, aimed at blocking the female hormone oestrogen, is also often part of the treatment in men. Often effectively, but also with burdening side effects. However, there was no scientific basis for giving men the same treatment as women yet. The researchers, led by Wilbert Zwart, have now evaluated hormonal function across all tumour DNA for the first time, comparing men and women.

Broad line: biologically hardly any difference

The first conclusion was that the vast majority of breast tumours in men and women are biologically indistinguishable. This provides a scientific basis for the current practice of giving men and women the same anti-hormonal therapy.

There are, however, differences in tumours with a less favourable prognosis

But, as is the case for women with hormone-sensitive breast cancer, there are also men whose cancer returns despite treatment. That group therefore probably benefits from a different or additional approach. And it is precisely in this group of men that the tumour’s DNA profiles appear to be gender-specific.

Step to tailored treatment

Wilbert Zwart: ‘We had previously seen that very specific patterns in women are predictive of the course of the disease. In patients with a less favourable course of the disease, other areas of the DNA are active under the influence of hormones. That says something about the therapy sensitivity of each individual tumour and this knowledge is essential when looking for customised therapy. We also see specific patterns in men which are different from women. The selection of medicines may therefore have to be slightly different if we are working towards a tailor-made therapy for men. But a lot of research is still needed for this’.


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