ReviewTreatment non-adherence in teenage and young adult patients with cancer
Introduction
Around 1800 teenagers and young adults (TYA), aged 13–24 years, are diagnosed with cancer in England each year.1 However, despite improvements in the efficacy of modern treatment, at least 30% of these patients will not be cured. Indeed, cancer remains the leading cause of non-accidental mortality within this age group.2 Biological factors, including metastatic potential, levels of tumour resistance, and differences in biology at different ages, especially when compared with children, account for a proportion of such treatment failures.3, 4 The poor gains in survival for some tumours might also be attributed to the poor accrual of TYA patients into clinical trials.4, 5, 6 With the recognition that adherence can be a major problem for adolescents diagnosed with other chronic health conditions,7, 8 it is indeed conceivable that adherence difficulties also contribute to the poor health outcomes seen in TYA patients with cancer.
Treatment adherence is a complex, multifaceted phenomenon, which has significant implications for therapeutic success, reliability of clinical trial data, and health-related quality of life.9, 10, 11 However, there is a paucity of studies examining treatment adherence in TYA patients with cancer. This might be due to the inference that patients with life-threatening conditions would be highly motivated to follow their treatment regimens.12 Another reason might be that because many components of cancer therapy were previously directly administered and controlled by medical professionals, the assumption is made that adherence would not be compromised in patients diagnosed with cancer. However, with the increased availability of oral antineoplastic agents and home delivery of some cytotoxic drugs, patients are now required to take on more responsibility for the administration of their treatment. Methodological issues, including controversy regarding the definitions of compliance and adherence, and the lack of psychometrically sound adherence measures also undoubtedly contribute to the paucity of data.13
To raise awareness of the adherence challenges faced by TYA patients with cancer, we have reviewed the available collective evidence. Previous reviews have included such studies. However, because some have reviewed studies recruiting patient cohorts ranging in age from childhood into early adulthood, it is difficult to draw meaningful conclusions about the adherence functioning specifically of TYA patients.10, 14, 15, 16, 17 The drug compliance of TYA patients with cancer has been reviewed.11 However, there are many components to cancer treatment. A clear, up-to-date synthesis of the published work on adherence to treatment in TYA patients with cancer is clearly warranted and forms the basis of this paper.
Because there are variable definitions in the published work of teenage and adolescence, both of these terms are used in this review.
Section snippets
Definitions of adherence and non-adherence
Compliance, defined as “the extent to which a person's behaviour, in terms of taking medication, following diets, or executing lifestyle changes coincides with medical or health advice”,18 has long dominated the published work. However, this approach implies submission and complacency, with the patient being a passive receiver of professional health advice.8 The term “adherence” has now gained prominence and refers to “the extent to which a person's behaviour (medications, diets, or lifestyle
Treatment non-adherence in TYA patients with cancer
Four studies22, 27, 28, 29 were identified that reported the non-adherence behaviour of TYA patients with cancer to oral medications. These studies showed between 27% and 63% of patients did not take their oral treatment as recommended. With the varied methods used in these studies, a quantitative synthesis of their findings is not appropriate. It is more informative to look closely at each study and we provide an overview of the individual studies in table 2.
Smith and colleagues27 analysed
Non-adherence and treatment outcome
To what degree might non-adherence actually affect therapeutic outcome? Dolgin and colleagues30 asked physicians to judge the extent to which they thought non-compliance affected prognosis in adolescent patients with cancer. They believed that non-compliance was a potential threat to outcome in six of 11 (55%) patients. However, in a second study, reported in the same paper, compliance was perceived as having detrimental outcome implications in only nine of 65 (14%) patients. Although the
Risk factors for non-adherence
Treatment adherence is not just a patient-driven phenomenon.7 Although a multitude of interacting variables (ie, patient, family, treatment, and health-professional factors) have been identified as key components affecting adherence in chronic illness,7, 13, 35 we report only those risk factors that have been investigated in the published work on adherence in TYA patients with cancer. Recognition of the risk factors that contribute to non-adherence allows the implementation of appropriate
Strategies
Strategies to foster greater adherence can be multifactorial, targeting issues concerning the patient, health professional, family, and treatment regimen.52 These approaches should be tailored to meet the needs of the individual.11, 53
It is paramount that adherence is never assumed.9, 11, 35 The accurate identification and assessment of non-adherence should be an integral component of care.41, 54
An understanding of why a TYA patient does not adhere is imperative.41 With the reluctance of some
Future research directions
Many adherence studies are hindered by small samples and one way of addressing this has been to recruit a heterogeneous group of patients, with respect to factors such as cancer diagnosis and length of time since diagnosis. Likewise, the grouping of teenagers and young adults is common. However, within this group there are of course cohorts of patients at very different physical, emotional, and psychological developmental stages. Collaborative efforts, both national and international, will help
Conclusion
The available evidence suggests that a substantial proportion of TYA patients with cancer have difficulties adhering to treatment and these difficulties are manifested in different ways and in response to different treatment demands. However, there are still many questions that remain unanswered. Can we prospectively identify which TYA patients are at risk of adherence difficulties? What are the mechanisms underlying treatment adherence? Which interventional programmes are most effective in
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