The scientific basis for more precise assessment of the risk of breast cancer is now in place. A very extensive cancer study has gathered data on a large range of common heritable factors that are significant for the risk of cancer. The results are could make it possible to individualise the offerings available to women for breast scanning and hopefully further reduce mortality.

Researchers at the Faculty of Health and Medical Sciences have been collaborating with various other countries and have now learnt so much about common heritable factors relating to breast cancer that determining the risk is precise enough for practical use. The results were published in several articles.

"We have established the scientific basis for being able to do risk assessments so precisely that we will hopefully be able to personalise the breast cancer screening offerings for every woman. A personalised risk-based screening programme will hopefully help us to further reduce mortality amongst women," said Clinical Professor Stig Bojesen, Department of Clinical Medicine.

Currently, all women aged between 50 and 69 are offered mammography. Screening works well and does reduce mortality but there are also some disadvantages such as false positives and over diagnosis which could probably be reduced by personalised screening programmes.

The articles are part of the biggest ever cancer study in the world. Taken individually, common heritable factors have very little significance for the risk of cancer. That is why researchers have collaborated in the so-called OncoArray Consortium to gather documentation and data on the genomes of 450,000 individuals.

In each individual, they have identified half a million locations on the genome associated with the risk of carcinomas of the breast, large intestine, lungs, rectum, ovaries and prostate. For each disease, we now know about a great number of common locations in the genome that help to decide whether there is a large or small risk of an individual developing a certain form of cancer. Stig Bojesen explaines: "Since these factors are heritable, we cannot change them. But we can for example assess the level of risk of a woman developing breast cancer and a what stage in her life this risk applies. This means we can individualise a screening programme that could possibly help us to catch cancer at an early stage or on the other hand, only start screening at a later stage. And it actually only means taking a blood test."

Changing the screening procedures for breast cancer is still somewhat in the future and will have to be thoroughly tested before being taken up. Stig Bojesen hopes that the results can be combined with other risks for breast cancer such as age, family history, lifestyle and imaging of breast tissue so that the risk can be assessed even more precisely.

Clinical Professor Stig Bojesen is at the Department of Clinical Medicine, University of Copenhagen and is Chief Physician at the Clinical Biochemical Department, Herlev and Gentofte Hospital. He has directed some of the work done in Copenhagen for the OncoArray Consortium.

The article titled, "Identification of ten variants associated with risk of estrogen-receptor-negative breast cancer," was published in the journal Nature Genetics.