Using a pragmatic cluster-randomized trial design, 20 Ontario cancer centres that provide care to patients with breast cancer will be randomly allocated to one of two arms: pro-active telephone toxicity management (intervention), or control (routine care). All patients with early stage (I-III) breast cancer who commence adjuvant or neo-adjuvant chemotherapy at participating institutions during the 6 to 12-month intervention period (will vary between centres depending on the number of incident cases) will be evaluated using Ontario healthcare administrative data. A sub-set of at least 25 patients at each participating institution will participate in a PRO sub-study involving the completion of standardized questionnaires to measure: a) severity of chemotherapy treatment toxicities; b) self-care for management of chemotherapy toxicities; c) self-efficacy (confidence) for managing symptoms; d) quality of life; and e) coordination of care. Patients participating in the PRO sub-study will be asked to provide consent to link their PRO data to Ontario healthcare administrative data so that correlations between the symptom self-assessments and Quality of Life (QoL) measures can be made with the administrative data on ED+H visits and use of supportive care medications. the investigators will compare the use of supportive care medications (i.e. anti-emetics, growth factors) by patients in the intervention and control arms to assess their influence on severity of chemotherapy-related toxicities as part of an exploratory sub-group analysis in patients \>65 years of age as administrative data on supportive care medication use is only available for this age group.
