Dose Reduction of Docetaxel-Based Chemotherapy in Vulnerable Older Women With Early-Stage Breast Cancer (DOROTHY)

Inclusion Criteria: * Ability to provided informed consent or a legally authorized representative is able to consent on behalf of the patient * Willing to answer questionnaires as part of their participation * Age: \>= 65 years by the time of study registration * Histologically or cytologically confirmed breast cancer(s) that is human epidermal growth factor receptor 2 negative (HER2-negative) per the most recent 2018 American Society of Clinical Oncology College of American Pathologists (ASCO CAP) guidelines relapsed/ refractory disease * Estrogen receptor and progesterone receptor immunohistochemistry (IHC) status must be known; any estrogen receptor (ER)/progesterone receptor (PR) status is eligible * Non-metastatic, invasive breast cancer (scans are not required to document non-metastatic disease- any staging work-up is up to the treating providers' discretion) * Recommended to have either standard dose neoadjuvant docetaxel, cyclophosphamide (TC) chemotherapy or adjuvant TC chemotherapy per their treating provider. Participant may be on immunotherapy concurrently with the protocol regimen at the discretion of the treating physician * Any surgery, nodal assessment, radiation, hormonal therapy is left up to the treating provider but should not occur concurrently with study therapy * Any patient who received pre-operative hormonal therapy and who is then recommended for neo/adjuvant chemotherapy is eligible, though hormonal therapy should be held during study treatment administration * For patients with bilateral or multifocal/multicentric breast cancers, the following criteria must be met to enroll: (1) both cancer are HER2 negative, AND (2) the provider feels the patient will benefit from TC for at least one of the cancers * Patients who do not speak or read English are eligible as long as adequate interpreter services are available or the surveys are available in the preferred language (i.e. the Geriatric Assessment \[GA\] and Patient Reported Outcomes \[PRO\] surveys are available in many languages) Exclusion Criteria: * Participants who have already received any chemotherapy for their current breast cancer * Patients with recurrent and/or metastatic disease will be excluded. Prior diagnoses of breast cancers (including ductal carcinoma in situ \[DCIS\]) are allowed, provided that the treating provider feels that the current cancer most likely represents a new primary breast cancer and not recurrent disease * History of allergic reactions attributed to compounds of similar chemical or biologic composition to cyclophosphamide and/or docetaxel * Past treatment with the regimen TC for prior breast cancer