Systemic therapy

Across diseases, adherence has been cited as the single most important modifiable factor that compromises treatment outcomes. This has provided a new challenge for optimizing patient adherence and management of treatment-related adverse events in the outpatient setting. A methodical approach is required for patient selection that is suitable for oral therapy, education of patient and caregiver, as well as support and monitoring from a multidisciplinary network of physicians, pharmacists, and other health-care providers involved in the patient care.

Adherence to medications is directly associated with improved clinical outcomes, higher quality of life, and lower healthcare costs in many chronic conditions [5-14]. Similarly, adherence is the key issue to success of oral cancer therapy use, particularly more so when patients require taking several tablets, when dosing-regimens are complex or intermittent, and when patients are elderly and potentially cognitively impaired [15-20]. The causes of non-adherence in elderly are complex and multifactorial. Patient-related, socio-economic, disease-related, therapy-related, health-care team, and age-related factors are general determinants and potential barriers to adherence [15, 21-25]. Management of elderly patients with cancer is equally influenced by many factors (e.g. comorbidities, geriatric syndromes, functional deficits, social resources, nutritional concerns, and polypharmacy) that frequently lead to reductions in life expectancy and tolerance to medical interventions. These same factors also impact their adherence to oral anticancer treatment. In this regard, methods to promote, measure, or monitor adherence to oral therapy is important.

Despite the increasing use of oral systemic therapy and substantial concerns with adherence and compromised outcomes, clinical trials have failed to include routine assessment of adherence to oral therapy. At the time of literature search, adherence studies have only been performed in a few oral therapies for breast (i.e. hormonal agents, capecitabine), CRC (capecitabine), GIST (i.e. imatinib), lung (i.e. etoposide, erlotinib), and prostate (i.e. bicalutamide, abiraterone, enzalutamide) cancers. Information remains lacking on adherence to a majority of oral chemo and targeted therapies in both clinical trials and clinical practice. For this reason, there are insufficient data to describe adherence to most oral systemic cancer therapy. However, in the majority of clinical trials on various cancer types, treatment discontinuation or withdrawal have been largely attributed to toxicity, particularly in the elderly. Therefore close monitoring and proactive management of these toxicities may be regarded as useful strategies to ensure adherence to oral systemic therapies.