A study looking at the genetics of ductal carcinoma in situ (ICICLE)

Cancer type:

Breast cancer





This study was to find genes that might increase the risk of ductal carcinoma in situ (DCIS).

DCIS is when some cells inside the tubes in the breast (the ducts) have started to turn into cancer cells. DCIS might develop into an invasive ductal breast cancer if it isn’t treated.

Cancer Research UK supported this study.

More about this trial

In this study, the researchers looked at the genes of a large number of women who had been diagnosed with DCIS. They found out more about their family history to see if any of their relatives had also had DCIS or breast cancer.

The aims of the study were to:

  • identify genes that might cause DCIS or increased the risk
  • try and identify which women with DCIS were more likely to develop invasive breast cancer if DCIS wasn’t treated 

Summary of results

The study team found this study provides the strongest evidence so far that DCIS like invasive breast cancer can be genetic. And that many of the genetic changes that cause invasive breast cancer also cause DCIS.

Researchers looked at the data of 38 studies of breast cancer and DCIS. From this there were:

  • 5,067 examples of DCIS (the majority of which came from the ICICLE study)
  • 24,584 examples of invasive breast cancer
  • 37,467 examples where there was no DCIS or breast cancer (control group)

The team looked at over 200,000 genetic changes in all the samples. They found that most of the 76 known genetic changes that increase the risk of invasive breast cancer also increase the risk of DCIS.

The researchers also looked at the examples according to whether they had receptors for the hormone oestrogen (ER positive). They found that there was a link between the genes that increase the risk of ER positive breast cancer and ER positive DCIS.

The study team didn’t find any genetic changes that only increased the risk of DCIS and not invasive breast cancer.

The team concluded that this study gives the strongest evidence to date that there is a shared genetic cause of DCIS and invasive breast cancer. Studies with larger numbers need to be done to determine if there are particular genetic changes that increase the risk of DCIS and not invasive breast cancer.

We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Dr Rebecca Roylance
Dr Elinor Sawyer

Supported by

Cancer Research UK
Breast Cancer Now
Experimental Cancer Medicine Centre (ECMC)
NIHR Clinical Research Network: Cancer

Other information

This is Cancer Research UK trial number CRUK/08/046.

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Last reviewed:

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