The purpose of this study is to examine the efficacy of a psychosocial eHealth intervention on the proposed primary outcomes, hormone therapy adherence and health related quality of life (HRQoL), in breast cancer survivors.

The intervention components include mindfulness-based stress reduction, breast cancer knowledge, stress awareness and management, social support, and enhanced communication. The intervention will be delivered via an online application over an 8-week period.

Participants are randomized into either an intervention application (described above) or a control application (health information and general health promotion strategies). Aside from having access to the online application for the recommended 8 weeks with weekly online focus groups, participation in this study includes four assessments: baseline (at the beginning of the research study), post-intervention (8 weeks after baseline), a 6-month follow-up and a 12-month follow-up.

Breast cancer is the most commonly diagnosed cancer among women in the U.S. Approximately 75% to 80% of breast cancer survivors are prescribed HT (hormone therapy) medication for 5 to 10 years following primary treatment. Five years of adjuvant HT among women with non-metastatic cancer reduces the risk of recurrences by 50%. Adherence to HT is also an independent predictor of breast cancer mortality, reducing the risk by up to 28%. HT-side effects, however, are not only a major source of distress but also among the most robust predictors of non-adherence to HT. Therefore, effective management and ability to reduce the burden of these side effects are critically important to achieve optimal HT adherence. Because HT side effects may persist for years and are not easily managed, MBSR's mind-body approach and emphasis on non-judgmental attitudes, acceptance, and uncertainty tolerance may be an especially beneficial approach to helping cancer survivors cope with the burdensome medication-related side effects, thus improving adherence to medication. The investigators propose that a mindfulness-based stress reduction (MBSR) intervention that has been efficacious in reducing HT side effects and improving HRQoL in cancer patients may also prove beneficial in improving HT adherence. After developing a web-based MBSR intervention and refining it via a usability trial, this study will establish the feasibility of a web-delivered, group based MBSR intervention to improve HT medication adherence and HRQoL in patients being treated for breast cancer. It is hypothesized that participants assigned to the MBSR intervention will have better primary outcomes than participants in the control group, which receives standard health information.

Inclusion Criteria:

1. ≥ 18 years of age
2. English-speaking (6th grade reading level) as required to complete assessments
3. medical chart confirmed diagnosis of hormone-receptor positive non-metastatic breast cancer
4. Stages I-IIIa
5. completion of any combination of surgical, radiation, and chemotherapy treatment
6. willingness to be randomized into study
7. have initiated HT within the past 6 months as data in literature indicates that the overwhelming majority of women who initiated HT are still adherent within the first 4 months
8. first-time diagnosis of breast cancer
9. access to a computer or tablet with Internet capabilities

Exclusion Criteria:

1. Visual, hearing, voice, or motor impairment that would prevent completion of study procedures
2. diagnosis of an unmanaged psychotic or psychiatric disorder (e.g., clinical depression, anxiety, or PTSD), bipolar disorder, dissociative disorder, or other diagnosis for which participation in this trial is either inappropriate or dangerous - this includes patients who have life-threatening illness (e.g., end-stage kidney disease) or diagnosis of a chronic disease that is associated with a major functional impairment (e.g., chronic severe pain, fibromyalgia)
3. Alzheimer's, dementia or history of stroke

Individual participant data (IPD) will not be shared with any researchers outside Northwestern.