Background: Chemotherapy treatment (CT) can have burdensome side effects such as fatigue, nausea-vomiting, and sleep problems that can significantly affect patients' quality of life. Fatigue is the most common, lasting and bothersome of these, which prevents people from working and carrying out daily activities. Mindfulness-Based Cancer Recovery (MBCR) is an evidence-based group training program which has shown to help treat negative physical and psychosocial symptoms in cancer patients. The investigators propose to evaluate a pilot-tested online-MBCR program for patients undergoing CT who may be low on energy, time or have compromised immunity.

Objectives: To evaluate the impact of participation in online MBCR during CT on fatigue (primary outcome), sleep, pain, nausea/vomiting, mood disturbance, stress symptoms and quality of life (secondary outcomes) as well as cognitive function and return to work (exploratory outcomes) over the course of treatment.

Methods: The study design is a randomized wait-list controlled trial, conducted during CT for patients with breast or colorectal cancer. Participants will take the 12-week online MBCR program at home within 2 weeks of randomization (immediate group) or after CT completion (waitlist group). Outcomes will be assessed online at, 1) Baseline, 2) Post-MBCR, 3) Post-CT (primary outcome) and 4) 12 months post-baseline.

Anticipated Findings: MBCR is a promising adjuvant program that could help patients prevent, delay or diminish aversive symptoms and side-effects associated with CT, particularly fatigue. If helpful, online-MBCR could be made easily available at cancer centers worldwide and significantly lessen the burden of cancer treatments.

Inclusion Criteria:

1. Men and women over the age of 18
2. Diagnosed with either a) stage I-III HER 2 normal breast carcinoma or b) Stage II-III colorectal carcinoma
3. Scheduled to undergo either neoadjuvant or adjuvant: a) FEC- D or AC-T chemotherapy or b) FOLFOX or CAPEOX chemotherapy
4. Weekly access to high-speed internet
5. Access to a computer/tablet/smart phone
6. Able to attend MBCR classes at scheduled times
7. Sufficient ability to speak and read English
8. Willingness to be randomized into immediate or waitlist groups and complete all assessments

Exclusion Criteria:

1. Metastatic patients
2. Suffering from current Major Depressive Disorder, Bipolar Disorder or other psychiatric disorder (self-report)
3. Currently engaging in meditation one or more times per week within the previous year.
4. Participation in an MBCR or MBSR program in the last five years.
5. Cognitive impairment (>6 on the Brief Screen for Cognitive Impairment)
6. Physical functional impairment that would interfere with the ability to participate in the intervention (on the PAR-Q questionnaire)