Using a pre-post study design, we evaluated the impact of a DST on decision making outcomes. The DST is based on a disease simulation model [5-7] that uses age at diagnosis and DCIS grade to predict patient-specific clinical impacts of six different treatment choices: (1) lumpectomy, (2) lumpectomy with radiation therapy, (3) lumpectomy with endocrine therapy, (4) lumpectomy with radiation and endocrine therapy, (5) mastectomy with or without reconstruction, and (6) bilateral mastectomy with or without reconstruction. Using this model, we designed a decision aid for clinicians that enabled a visual and numeric comparison across treatment strategies [3]. In collaboration with patient advocates and patient partners, this clinician-facing tool was subsequently adapted into an online patient-facing DST presented in this paper [4].

The DST was implemented through the website www.DCISoptions.org in collaboration with the COMET (Comparison of Operating to Monitoring, with or without Endocrine Therapy) study, a randomized trial of surgery versus active surveillance for low-risk DCIS. Users of the site were asked to provide age and DCIS grade, to access personalized information about predicted clinical impacts related to specific treatment choices. Patients were then asked to select one or more of the six treatment options for which they wished to have outcome information. General information for each treatment option, including active surveillance, was also provided in descriptive terms. Personalized 10-year risk predictions, including (1) subsequent development of DCIS or invasive breast cancer in the same breast, (2) the risk of dying from causes other than breast cancer, and (3) the risk of dying from invasive breast cancer, were communicated for each treatment using icon arrays (Fig. 1A-B).

A Outcomes Icon Array after Lumpectomy + Radiation. Example predicted patient specific 10 year outcomes for a 55 year old user with ‘low or intermediate grade’ DCIS who chooses treatment with ‘lumpectomy + radiation’. B Outcomes Icon Array after Mastectomy. Example predicted patient specific 10 year outcomes for a 55 year old user with ‘low or intermediate grade’ DCIS who chooses treatment with ‘mastectomy’

While engaging with the website, site participants were asked to complete two surveys, one prior to interacting with the DST and one after. The survey assessed (1) impact of the DST on awareness of treatment options for DCIS, (2) impact of the DST on willingness to consider these options, (3) impact of the DST on knowledge of recurrence/mortality risks associated with DCIS, and (4) how helpful the DST was to them (“How helpful or not helpful was this decision tool in making a treatment decision for DCIS?”).

Participants were those who visited the COMET website and engaged with the online DST and associated surveys. This protocol is approved by Quorum Centralized Institutional Review Board (dated July 11, 2018).

We used chi‐square tests to compare the distribution of age group (40–49, 50–59, 60 + years) and DCIS grade among patients who completed both the pre- and post-tool survey and those who only completed the pre-tool survey. Median age was compared using the Wilcoxon-Mann–Whitney test.

We focused on the cohort that answered both surveys to analyze potential differences in responses between the pre- and post-tool survey. The McNemar test was used to compare percentage distributions and the paired t-test was used to compare mean responses for questions using the Likert scale. We used the Wilcoxon signed rank test to compare median changes from pre- to post-tool survey. All statistical analyses were performed using SAS software, version 9.4 (SAS Institute, Inc., Cary, NC). Statistical significance was defined as P < 0.05 in a two‐sided test. Data quality was ensured by review of data the study chairperson following Alliance policies.