SmART Heart: Study of mHealth Apps to Reduce Cancer-Treatment Effects on the Heart

Inclusion Criteria:

* Prior diagnosis of an acute leukemia or lymphoma or any receipt of HCT for a malignant condition.
* At time of approach, \>= 5 years from initial cancer diagnosis or \>= 5 years from first HCT, whichever is later.
* Currently in remission and not on any active anti-cancer therapies (survivors receiving maintenance tyrosine kinase inhibitors are NOT eligible).
* Able to read, write, and speak English.
* Access to smart phone or computer with internet access.
* Presence of at least 1 CV risk factor:

  * Currently on medication for hypertension, or
  * Currently on medication for cholesterol or triglyceride, or
  * Currently on medication for diabetes, or
  * Currently not physically active (self-reported average \< 30 minutes/day), or
  * Currently smoking.
* Ability to understand and the willingness to provide informed consent.

Exclusion Criteria:

* Pre-existing ischemic heart disease (includes angina if documented in electronic medical record \[EMR\]) or ongoing symptomatic cardiomyopathy (those with asymptomatic cardiomyopathy may be allowed to participate if they do not have any current activity restrictions, but we will seek physician clearance for any submaximal exercise testing).
* Active systemic treatment for graft versus host disease.
* Currently pregnant. However, participants enrolled who become pregnant after randomization can remain on the study.