The investigators hypothesize that the implementation of a Web-application in patients initiating adjuvant hormone therapy for breast cancer brings a benefit on treatment adherence and quality of life.

Inclusion Criteria:

• Patient > 18 years old
• Breast cancer patient candidate for adjuvant hormone therapy
• Mastery of the French language
• Patient with a cell phone and an Internet connection
• Patient able to use a computer, smartphone, or tablet.
• Patient affiliated to a social security system
• Signing of informed consent prior to any specific study-related procedure

Exclusion Criteria:

• Patient who has previously received hormone therapy for cancer.
• Patient not trained in the use of the application
• Any associated medical or psychiatric condition that might compromise the patient's ability to participate in the study
• Patients with locoregional or metastatic recurrence
• Other history of cancer.
• Patient deprived of liberty, under guardianship or curatorship
• Simultaneous participation in a therapeutic clinical trial or other clinical study involving a connected tool
• Patient unable to undergo trial follow-up for geographical, social or psychopathological reasons