The COMET Study will look at two different treatment approaches for managing low-risk DCIS, described below and shown in Table 1:

Table 1. Summary of the COMET study treatment approaches
SurgeryActive Monitoring
Treatment approach
  • An operation to remove the DCIS.
  • Regular monitoring of the DCIS.
Aim of treatment approach
  • To remove the DCIS, which may lower the risk of invasive breast cancer.
  • To monitor the DCIS with regular mammograms, to avoid surgery unless or until there is evidence of invasive breast cancer.
Details of treatment approaches
  • Surgery can be a lumpectomy or mastectomy operation, depending on the size of the DCIS, recommendation of the surgeon and patient preference.
    Lumpectomy: a portion of the breast containing the DCIS is removed.
    Mastectomy: the whole breast containing the DCIS is removed.
  • Radiation therapy may also be given, based on a discussion with your doctor that incorporates information such as your medical history, what surgery you had, and the pathology findings.
  • A check-up and mammogram six months after you join the study. The mammogram will check for changes in the breast.
  • If there are no changes, you can stay on Active Monitoring and return in six months for the next mammogram and check-up.
  • If there are changes seen, they would be discussed with you and you might have a biopsy.
  • Your options would be to stay on Active Monitoring or change to have surgery.
Hospital stays and visits
  • Lumpectomy is generally an outpatient surgery. You go home the same day.
  • Mastectomy for DCIS may be done as an outpatient, or you may stay overnight.
  • If the breast is reconstructed, this lengthens the initial hospital stay to 3-5 days and you may require further operations, with recovery each time.
  • Radiation treatment generally requires daily visits over 3 to 6 weeks. You lie on a table and radiation is targeted to the breast or chest. You will not feel the treatment itself.
  • You will have check-ups after surgery, a check-up every six months and a mammogram every year.
  • You will have a visit for a mammogram six months after joining the study.
  • You will have an appointment to discuss the findings with the specialist.
  • If you stay on Active Monitoring, you will need to return every six months for a mammogram and check-up.
  • If you have changes on a mammogram, you may need further tests such as a biopsy.
  • If the tests suggest invasive cancer, you will be recommended to have surgery, with or without radiation therapy.
  • See the left-hand column for details of surgery and radiation.
Time off work or usual activities
  • With lumpectomy or mastectomy, most people need 1-3 weeks off work after the surgery.
  • With breast reconstruction, most people need 3-6 weeks or more off work after each surgery.
  • With radiation, some people may need 2-4 weeks off work, starting toward the end of treatment.
  • There is no recovery time.
  • You will need to take an hour or two out of your work and usual activities for the mammogram and check-ups every six months.
Endocrine therapy
  • Can be taken to block hormones that are associated with cancer growth. You can discuss this option with your doctor.
  • Can be taken to block hormones that are associated with cancer growth. You can discuss this option with your doctor.