Overview

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
	Surgery	Active 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.