LORIS LogoOverview


LORIS: A Phase III Trial of Surgery versus Active Monitoring for Low Risk Ductal Carcinoma In Situ (DCIS).

Ductal carcinoma in situ (DCIS) is an abnormality of the milk ducts in the breast but not in any other breast tissue.  DCIS accounts for approximately 20% of breast ‘cancers’ detected by breast screening. Currently, all DCIS is treated by surgery because of concerns that it may become an invasive cancer if left untreated but many experts now believe that some cases of DCIS are unlikely to ever cause any problems in the woman’s lifetime. The LORIS Trial randomises patients with low risk DCIS to standard surgery or to active monitoring with annual mammography. 




DCIS means that there are abnormal cells in the milk ducts in the breast but not in any other breast tissue. DCIS can be classified as high, intermediate or low grade. Because high grade DCIS is more likely to become breast cancer, it is treated as if it is an invasive cancer, but many doctors are not sure that low or intermediate grade DCIS would ever become invasive cancer.

Most women have surgery to remove DCIS. This may be surgery to remove the breast, a mastectomy, or it may be surgery to remove just the area of the breast containing the DCIS, a wide local excision.

In this trial, some women will have surgery and some won’t have surgery but will have a mammogram once a year for 10 years. The aim of the trial is to learn whether women with low risk DCIS can safely avoid having surgery, to assess whether active monitoring is non-inferior to surgery in terms of ipsilateral invasive breast cancer free survival time.

Inclusion criteria


  • Female, aged ≥ 46 years
  • Screen-detected or incidental microcalcification
  • Histologically confirmed diagnosis of non-high grade DCIS confirmed by local pathologist (for both breasts if bilateral disease) by: Small volume core biopsy and Vacuum Assisted Core Biopsy (VACB) or Vacuum Assisted Core Biopsy (VACB) alone as first line diagnostic approach or Small volume biopsy or VACB plus open diagnostic surgical biopsy (without clear margins) or open diagnostic surgical biopsy (without clear margins) (in accordance with the current NHSBSP Guidelines for Pathology Reporting in Breast Cancer Screening)
  • DCIS diagnosed ≤90 days before registration
  • Bilateral DCIS is permitted if non-high grade DCIS is confirmed in both breasts at the time of mammogram and diagnostic biopsy
  • Able to give informed consent and comply with the trial schedule and completion of Patient
  • Reported Outcome questionnaires
  • Patient fit and willing to undergo surgery
  • Written Informed Consent obtained

Further information


You can find further information about this trial on the LORIS website here or by contacting LORIS@trials.bham.ac.uk