As the population of older adults with metastatic breast cancer (MBC) continues to grow, treatment requires a more individualized and nuanced approach. Balancing treatment efficacy and tolerability with quality of life by incorporating geriatric assessments, evaluating functional status, and applying tailored dosing strategies is important to optimize care in this patient population.

When treating older patients with MBC, determining how to individualize care is an issue that we face routinely in clinical practice. One of the shortfalls of current clinical evidence is that older patients (≥65 years of age) are largely underrepresented in both advanced and early-stage breast cancer studies. Due to the lack of information on this patient population, we do not really know how a therapeutic agent may impact older adults (eg, dosing and toxicities).

In my practice, we often refer our older patients for an initial comprehensive geriatric assessment to help guide both treatment selection and toxicity management. Some assessments that we use include the Eastern Cooperative Oncology Group Performance Status (ECOG PS) Scale and the Karnofsky Performance Scale (KPS). These tools help determine the functional status of the patient at any given time and can be quickly administered in the clinic.

We also use the Cancer and Aging Research Group Chemotherapy Toxicity Tool (CARG-TT; Cancer and Aging Research Group), which is tailored specifically for the older patient population—vs standard Common Terminology Criteria for Adverse Events (CTCAE) grading—and helps assess toxicities. So, if a patient is experiencing a side effect, we can grade the event in the context of the age of the patient. As an example, if I had an older patient, I would start with a lower dose of ribociclib (400 mg). This is based on the AMALEE phase 2 study, which looked at frontline therapy in ER+ advanced breast cancer. Researchers found that 400 mg and 600 mg of ribociclib resulted in a similar progression-free survival in all patients. This is reassuring, since we know that older patients experience high rates of neutropenia on CDK4/6 inhibitors at higher doses.

The median age at diagnosis for advanced/MBC is around 60 years. However, if you make treatment decisions simply based on age, you may withhold effective treatment from a patient. Many oncologists are concerned about giving chemotherapy to older patients, but there is evidence that doing so may be beneficial, at least in early-stage breast cancer. We really should be assessing functional age/status instead (ie, looking at life expectancy markers such as comorbidities [eg, diabetes, cardiovascular disease, and stroke], along with the results from the geriatric-specific oncology tools I mentioned).