Perspectives on Functional Status in Older Adults with Cancer: An Interprofessional Report from the International Society of Geriatric Oncology (SIOG) Nursing and Allied Health Interest Group and Young SIOG

Abstract

Most adults with cancer are over 65 years of age, and this cohort is expected to grow exponentially. Older adults have an increased burden of comorbidities and risk of experiencing adverse events on anticancer treatments, including functional decline. Functional impairment is a predictor of increased risk of chemotherapy toxicity and shorter survival in this population. Healthcare professionals caring for older adults with cancer should be familiar with the concept of functional status and its implications because of the significant interplay between function, cancer, anticancer treatments, and patient-reported outcomes. In this narrative review, we provide an overview of functional status among older patients with cancer including predictors, screening, and assessment tools. We also discuss the impact of functional impairment on patient outcomes, and describe the role of individual members of an interprofessional team in addressing functional impairment in this population, including the use of a collaborative approach aiming to preserve function.

Introduction and Definition of Functional Status

The majority of adults with cancer are over 65 years of age, and this cohort is expected to grow exponentially in the next decade [1–2]. Compared to younger adults, older adults are more likely to have comorbidities that increase their risk for adverse effects from anticancer treatments, including functional impairment [3–4]. Functional impairment involves deficits in a range of abilities related to meeting the needs of daily life, including physical, social, spiritual, psychological, and intellectual needs [5–6] and is prevalent among older adults with cancer [7–8]. Moreover, older adults with cancer have a higher prevalence of geriatric syndromes, including functional impairment, frailty, and falls, compared to those without cancer [9]. Frailty, a clinical syndrome, can be defined as a critical depletion of physiological reserve in which even minor stresses may lead to severe and irreversible compromise in functional status [10].

Functional status is a significant concern among older adults with cancer because it is associated with adverse cancer outcomes. While oncology clinical trials frequently use overall and progression-free survival as primary endpoints, functional impairment may be a more meaningful outcome for older adults. This is because it negatively affects quality of life, and older adults with cancer may value preservation of independence more than survival benefits [11–13]. Functional impairment also leads to institutionalization and increased use of healthcare services [14] and it predicts chemotherapy toxicity and shorter survival in older adults with cancer [15–17].

Healthcare professionals caring for older adults with cancer should be familiar with the concept of functional status and its implications. For example, understanding how to evaluate functional status to identify and implement suitable interventions that can optimize the patients’ treatment and/or supportive care trajectory and quality of life [18–20]. The International Society of Geriatric Oncology (SIOG) and the American Society of Clinical Oncology (ASCO) have developed guidelines that recognize functional status as a core domain of geriatric assessment (GA) and endorse its use in determining care for older adults with cancer [21–22]. Furthermore, because of the significant interplay between functional status, cancer, anticancer treatments, and patient-reported outcomes, clinicians should also prioritize communication amongst the interprofessional team involved in caring for older patients. Functional status should be a key priority for healthcare professionals and investigators in the field of geriatric oncology [23].

In this narrative review, we provide an overview of functional status among older patients with cancer, including predictors, screening, and assessment tools, discuss the impact of functional impairment on patient outcomes, and describe the role of individual members of the interprofessional healthcare team in addressing functional status issues in these patients, including the use of a collaborative cancer care approach aiming to preserve function.

Risk factors and predictors of functional status in older adults with cancer

A clearer understanding of the factors associated with functional impairment may improve therapeutic decision-making and inform interventions to optimize functional status. Previous studies of older adults with cancer have evaluated factors associated with functional status trajectories over two or more time points [7, 24–29]. These studies were heterogeneous, and many aimed to predict functional changes after cancer diagnosis, treatment initiation (e.g., surgery, radiation), and treatment completion [7, 25, 27]. Factors associated with functional resilience (e.g., recovery of function between two time points) have also been investigated [7]. These studies found that predictors of functional decline include patient/clinical characteristics, disease characteristics, and treatment-related factors [26–28]. Among patient-related factors, older age, non-white race, unmarried status, lower education status, lack of health insurance, smoking, low physical activity, low chemotherapy preference, and coping strategy are associated with functional decline [26–28, 30]. The role of sex/gender in functional decline following cancer treatment is unclear [25, 27, 31].

Several disease- and treatment-related factors have also been shown to predict functional decline. These include type of malignancy (e.g., lung, colorectal, or breast cancer), disease stage, cancer progression, and type of treatment received [26–27, 30]. Among clinical-related factors, baseline impairment in functional status/physical function, polypharmacy, depression, abnormal nutritional status, cognitive impairment, comorbidities, presence of specific symptoms (e.g., dyspnea, fatigue, weakness), and higher symptom burden are associated with functional decline [25–29, 32–35].

Older adults experiencing frailty can be particularly vulnerable to functional impairments and to the adverse changes in health status [36]. Frail older adults often have multiple chronic conditions, geriatric syndromes, difficulty maintaining functional independence, and increased vulnerability to cancer treatment toxicities [37–38], and they are also more likely to experience a decline in physical functioning over time compared to non-frail adults [39].

Nonetheless, functional impairment may not be easily detectable using routine approaches, which supports the role of a comprehensive geriatric and symptom assessment in older adults with cancer [15, 40–41].

Measurement instruments and tools for functional status assessments

There are two primary ways to measure functional status: patient self-reported measurements (or caregiver/proxy-report) and/or healthcare professional (such as nurses, occupational therapists, physical therapists, and physicians) reported using performance-based measurements [42]. These categories are not mutually exclusive since self-reported tools may also be observations by healthcare professionals, that is, clinician reported.

Most patient self-reported measurements involve asking the patient about their ability to perform specific tasks as part of daily life, whereas performance-based measurement directly assesses the patient’s ability to perform certain tasks and activities. Performance-based measures and self-report measures provide complimentary information. Self-report measures may identify changes at lower levels of function (such as needing help with bathing or dressing) while performance-based measures may identify changes at a higher level of functioning sooner (e.g., changes in function such as slowing down during walking but no disability yet). For example, self-report measures may allow patients to report functional difficulties that clinicians would not detect during an office visit such as “I’m unable to open my pill bottles”. Meanwhile, performance-based measures may identify older adults who look fit for treatment without noticeable disability but have impaired balance. Thus, combining both may be even more informative [43]. Commonly used functional status instruments and performance measures are detailed in both Table 1.

Table 1:

Overview of Commonly Used Functional Status Self-Reported Measurements and Performance Tests in the Older Adult Oncology Setting

Self-Reported Measurements	Performance Measurements
ADL (Katz index) IADL (Lawton scale) Barthel index (any version) Nottingham Extended ADL Scale ADL (subscale of the Medical Outcomes Study Physical Health) IADL (subscale of Older American Resources and Services Scale [OARS]) Medical Outcomes Study Physical Health Questionnaire (any version) Patient-Reported Outcomes Measurement Information System (PROMIS) - Global	Timed Up and Go test Hand grip strength Short Physical Performance Battery Gait speed, gait assessment Chair stand test 6-minute walk

Measurement instruments and tools for functional status assessments

The Katz activities of daily living (ADL) index and the Lawton instrumental activities of daily living (IADL) scale are functional status measurements recommended for older adults detailed in the ASCO guidelines [22, 44–45].

Katz index:

The Katz index assesses functional status as a measurement of the patient’s ability to perform ADL independently [44]. ADL include bathing, dressing, toileting, transferring, continence, and feeding, with patient responses scored in each domain. Functional decline corresponds to impairment in at least one of the six activities over two different time points, which may suggest the need for intervention. As an alternative to the Katz index, clinicians sometimes use the Barthel Activity Index, which is useful in rehabilitation for adults with stroke [46]. This index consists of 10 items, including bowel and bladder continence, feeding, grooming, dressing, transferring, toilet use, mobility, stairs, and bathing.

Lawton scale:

The Lawton scale measures IADL and includes more sophisticated activities [45], such as the ability to use the telephone, shop, cook, do housekeeping and laundry, take medications, use transportation, and manage finances. Adults are scored according to their highest level of functioning in that category, ranging from low function (dependent) to high function (independent). Based on this tool, a patient is deemed dependent when at least one activity is impaired. As an alternative to the Lawton scale, other measures for IADL include the subscale of Older American Resources and Services Scale (OARS) or the Patient-Reported Outcomes Measurement Information System (PROMIS) measures of physical function and participation in social roles and activities [47–49].

Physician assessments:

Two additional measures are widely used by oncologists to assess the functional status of patients with cancer. The Eastern Cooperative Oncology Group (ECOG) Performance Status assigns scores ranging from 0 (fully active) to 5 (dead) to assess function [50]. The Karnofsky Performance Status measure assigns scores ranging from 0 (dead) to 100 (perfect health) [51]. Despite their wide use, these tools are poor descriptors of function because functional impairment can occur alongside a good performance status [52].

Performance Measurements

Timed Get Up and Go (TUG):

The Timed Get Up and Go (TUG) is a simple test used to assess fall risk, physical mobility and physical reserve. It requires both static and dynamic balance [53]. With the TUG assessment, the patient is timed while rising from an armed chair, walking 3 meters, turning around, walking back, and sitting back down in the chair [54].

Handgrip strength (HGS):

Handgrip strength (HGS) measures upper extremity strength, which can be relevant information as upper extremity limbs are essential to ADL [55–56]. HGS can be also used as a proxy to assess overall strength and level of frailty [57–59]. Patients squeeze a dynamometer as hard as possible with their dominant hand. The final handgrip strength score, presented in kilograms (kg), is calculated as the average score of three successive attempts with rest in between [60].Clinical thresholds indicating impairment are available from the manufacturer and are specific based on right or left hand, sex, and age. Grip strength is predictive for several adverse outcomes of cancer treatment, including ADL impairment, frailty and mortality [35, 61–63].

Short Physical Performance Battery (SPPB):

The Short Physical Performance Battery (SPPB) measures lower extremity function, in particular, static balance, gait, and walking speed, which are important domains of functional ability [64–65]. SPPB includes three timed tasks (walking speed, standing balance, and chair stand tests) [66–67] and can be performed in any clinical environment with a walkway longer than 5 meters so the patient can walk comfortably while being timed. Clinically meaningful changes are defined as 0.1 m/sec. The chair stand test evaluates lower extremity strength while the patient gets up and down from sitting in a chair to full stand 5 times as quickly as possible. The balance test requires patients to hold their feet together, semi-tandem and tandem, each, for 10 seconds to assess fall risk due to balance issues.

Impact of functional impairments on patient outcomes

Many older adults with cancer present with functional impairments in ADL (17–19%), and many experience a decline in IADL after receiving cancer treatment (41–59%) [7–8]. Baseline functional status is key to inform therapeutic goals and expectations for cancer management. Functional status changes should be interpreted in the context of older individuals’ needs and goals rather than simply in the framework of their comorbidities. Frequently, impaired function can be the first sign of disease onset or inadequate social support. Monitoring functional status is crucial to adjust discharge plans and is particularly useful to follow the progress of patients with chronic conditions including cancer. The impact of functional decline on outcomes of older patients with cancer is outlined in Figure 1.

Figure 1:

Impact of functional decline on outcomes of older patients with cancer

Two tools are available to assess the impact of functional status on treatment toxicity including the Chemotherapy Risk Assessment Scale for High-Age Patients (CRASH) [17] and the Cancer and Aging Research Group (CARG) toxicity calculator [16]. The CRASH tool has shown that limitations in IADL predict the risk of hematological and non-hematological toxicity [17]. Additionally, the CARG toxicity calculator has shown that the presence of falls in the previous 6 months or limitations in walking 1 block predicts the risk of grade 3–5 chemotherapy toxicity [16]. Aside from toxicity calculators, functional dependence defined as ECOG performance status of 2–4, was shown to increase the risk of chemotherapy toxicity in patients with ovarian cancer aged ≥ 70 [68]. In another study, among older adults with cancer and an ECOG performance status score of 0–1, 9% had restrictions in ADL and 38% had restrictions in IADL which demonstrated that older adults with an ECOG good performance score may have underlying functional impairment [69].

Interprofessional team member roles in assessing and managing functional status

Physicians and advanced practice providers

Physicians caring for older adults with cancer may include the primary oncologist (medical, surgical, or radiation), geriatric oncologist, geriatrician, palliative care physician, or primary care physician. Physicians can obtain information related to functional status directly through clinical encounters or by working closely with other team members (e.g., nurse, advanced practice provider, occupational therapist) trained in collecting these data, depending on local expertise and resources. Geriatric oncologists or geriatricians may assist with more comprehensive functional status assessment and co-manage patients alongside the primary oncologist. Physicians may use functional status information to guide treatment decision-making, assess impact of cancer and treatments, frame conversations with patients and caregivers, determine the need for and place referrals to relevant members of the interprofessional team.

Nurses

Nurses play a central role in the interprofessional team by collecting and synthesizing information related to functional status using the clinical measurement tools described above [70–72]. Nurses actively facilitate care coordination for older adults by working in collaboration with other members of the interprofessional team to implement recommendations that impact cancer care and treatment, which has potential to improve patient functional status [73–74]. Functional limitations uncovered during nurse-led functional assessment can trigger referrals to relevant interprofessionals including but not limited to physical therapy, occupational therapy, and/or social work [74]. Additionally, the nurse’s role includes fostering communication among interdisciplinary team members, which is vital to effective collaboration [70] as often several disciplines may be involved to address a single issue in the care of older adults in the oncology setting. The role of nursing includes bridging relationships between specialists and primary care providers through timely communication and sharing of pertinent information [75–76], and following up with older adults and their caregivers to support implementation of GA-informed recommendations [70].

Rehabilitation specialists

The cancer rehabilitation team may include an occupational therapist, physical therapist, speech and language therapist, physiatrist, rehabilitation psychologist, and rehabilitation nurse, among others [77]. Each team member has a scope of practice and guidelines that direct the evaluation and treatment of functional status and impairment. Patients benefit most when rehabilitation specialists work together to improve their activity participation and functional status [78–79].

Occupational therapists focus on what “occupies” time, in other words, the activities people engage in, from the basic (e.g., dressing, bathing, grooming) to the complex (e.g., working, managing money, medication schedules, higher-level cognitive tasks) [80]. Occupational therapists are trained in evaluation of function as a ‘means to an end’ and as ‘means towards intervention’. In occupational therapy, the evaluation and treatment are commonly structured within the activity itself and can range from evaluation of kitchen use and cooking, to grocery shopping or to basic self-care tasks such as re-training dressing skills; goals focus directly on function, ADL/IADL and engagement in life and social roles (e.g., father, leader, volunteer). Specifically, functional assessments evaluating the motor and cognitive processes observed in functional, daily tasks are the gold standard in occupational therapy evaluations. An occupational interview is used to develop a full profile and activity analysis as part of the plan of care [81]. In treatment, occupational therapists can adapt and create equipment by changing environmental factors in ways that allow for functional independence [82]. Occupational therapist can provide care throughout the cancer continuum from diagnosis through end of life [80, 83–84] thus patients experiencing functional impairment benefit from occupational therapy [85].

Physical therapists examine body systems to determine treatment and are experts in physical mobility and structural needs for movement. Focusing on body function, structures and activity allows physical therapists to evaluate a functional activity or task from a body systems perspective, and treat to the underlying impairment to allow for better function [86].

Speech and language therapists are specialists in production of speech, swallowing, and language. Improving speech production and language can positively affect IADL. For individuals with head and neck cancer or those on radiation treatment, speech and language therapists are critical in assisting, preventing, and/or improving structural issues related to jaw mobility (e.g., lockjaw) swallowing, and lymphedema. Furthermore, some speech and language therapists are trained in cognitive rehabilitation and can evaluate and treat cancer-related cognitive decline, especially as it relates to language and speech production difficulty (e.g., word recall) [87–88].

Prehabilitation, the provision of rehabilitation services at diagnosis, typically before surgery, can also prevent or limit the impact of treatment and improve functional recovery [89]. Individuals with lung, colorectal, and breast cancer who underwent prehabilitation prior to surgery had improved functional mobility for ADL/IADL and decreased hospital length of stay [90–93]. Prehabilitation has historically focused only on the period of diagnosis and primary therapy, instead of focusing on a prospective, longitudinal period throughout the entire cancer care continuum. However, researchers have called for future studies to examine the impact of a prospective surveillance rehabilitation model [77, 79]. This approach holds potential to address declines in function earlier when they are easier to treat [79].

Pharmacists

Functional impairment can affect the way patients are able to administer and manage their medications. One of the items on the Lawton scale for IADL includes the patient’s ability to take medications, which relies to some degree on both cognition and physical function [45]. In cases where cognitive impairment and functional impairment exists, the patient is not able to read and understand medication directions for safe self-administration, not be able to adhere to complex oral chemotherapy directions (e.g., take once daily for 21 days, then 7 days off), and not able to understand complex medication-related adverse events, which requires self-monitoring and reporting. In cases where functional impairment exists, the patient may not be able to independently open child-proof medication containers or self-administer injectable medications such as insulin.

Older adults with cancer are at a high risk of polypharmacy, with many meeting the definition for polypharmacy prior to the initiation of anticancer therapy [94–103]. The relationship between polypharmacy, functional impairment, and frailty has been closely examined and reported in the geriatric and geriatric oncology literature [27, 104–107]. Potential underlying mechanisms connecting polypharmacy to functional decline are summarized in Table 2 [104].

Table 2.

Proposed Mechanisms to Elucidate the Impact of Polypharmacy on Functional Status

Factors	Proposed Mechanism
Age-related regression of function reserve affects drug pharmacokinetics and pharmacodynamics	Reduced physiologic resilience and altered drug metabolism and/or drug clearance increases susceptibility to adverse drug reactions. Medication dose-adjustments may be warranted, if applicable.
Increased number of medical conditions increases the risk for drug-disease interactions and/or drug-geriatric syndrome interactions	A drug-disease interaction is an event in which a drug intended for therapeutic use causes harmful effects due to a comorbid disease, condition or syndrome (e.g., using diphenhydramine for seasonal allergies in a patient with cognitive impairment or a history of falls).
Increased number of medications increases the risk for drug-related toxicities or drug-drug interactions	Increased number of medications may lead to cumulative drug toxicity. The risk for drug-drug interactions approach 100% when 8 or more medications are used concurrently.
Use of medications in which the risk outweighs the benefit	Benzodiazepines and anticholinergic drugs (e.g., oxybutynin, amitriptyline) may interfere with memory, alertness, and orientation, leading to delirium, falls/fractures, and other adverse reactions.

Pharmacists play a particularly important role in the inter-professional, patient-centered cancer care team by addressing polypharmacy and its impact on functional impairment. Oncology pharmacists have training and expertise to optimize outcomes by providing evidence-based, patient-centered medication therapy as part of team-based care [108]. Because polypharmacy may be a potentially modifiable risk factor for functional decline it is imperative that pharmacists and other members of the cancer care team can screen for polypharmacy using validated tools [109–111] in order to identify opportunities to deprescribe high-risk medications and/or unnecessary medications. Pharmacist-led pilot studies have proven to be effective at reducing polypharmacy [112–116], yet a critical need remains for randomized controlled trials that demonstrate successful and scalable medication interventions that preserve, reverse or delay functional impairment and frailty in older adults with cancer.

Dietitians

Malnutrition is a common but often overlooked side effect of cancer and anticancer treatments, affecting up to 80% of patients depending on the tumor type/stage and causing nearly one in five cancer-related deaths [117]. The malnutrition results from systemic inflammation that causes anorexia, tissue breakdown, and loss of muscle mass and strength (sarcopenia) and that can result in significant loss of body weight, alterations in body composition, and functional decline [118]. Furthermore, older adults with cancer may be malnourished before a diagnosis and treatment plan are established. Therefore, it is critical to incorporate a screening process utilizing the appropriate tools to identify malnutrition early in patients’ treatment. According to the Academy of Nutrition and Dietetics, the 2-item Malnutrition Screening Tool (MST), which measures appetite and recent unintentional weight loss, is valid and reliable for identifying malnutrition risks in adult oncology patients in the ambulatory/outpatient setting [119].

Any patient determined to be at risk of malnutrition should be referred to an oncology dietitian and evaluated for possible interventions. To diagnose malnutrition, at least 2 of the following 6 clinical characteristics must be present: insufficient energy intake, weight loss, muscle mass wasting (sarcopenia), body fat depletion, fluid accumulation, and grip strength [120]. If a patient has been diagnosed with malnutrition, an immediate and complete review of nutritional impact symptoms by a dietitian will help determine cause. These include loss/absence of appetite (anorexia), episodes of nausea and/or emesis, diarrhea and/or constipation, difficulty with chewing and swallowing (odynophagia, dysphagia), oral health, taste alterations (dysgeusia), early satiety, and fatigue. Any social challenges, including difficulty obtaining food and physical inability to cook meals, should be explored.

Dietitians can provide input throughout the entire cancer care continuum. Parenteral and enteral feeding and oral nutritional supplements may be considered. Dietitians may also introduce antiemetics, appetite stimulators, and other appropriate medications. An inter-professional, shared-care approach including dietitians may significantly improve the detection and management of malnutrition among older adults with cancer. Improving gait speed and chair stand, in combination with nutritional intervention, could be a target for interventions to improve function and prevent or improve malnutrition-related negative health outcomes.

Caregivers

As cancer care has moved predominantly to the ambulatory/outpatient care setting [121], caregivers (e.g., family or friends providing unpaid care) are often the main providers of day-to-day support to older adults with cancer [122]. This support is influenced by older adults’ prognosis, disease severity, and goals of care and may include direct care, assistance with ADL/IADL, case management, emotional support, companionship, and medication supervision, all of which help to recover and/or maintain functional ability [123–125]. Functional independence of older adults with cancer is a major predictor of their caregivers’ quality of life, with more functional impairment associated with higher caregiver burden [126–127]. Informal and formal interventions such as home health care and community support may improve outcomes for both older adults with cancer and their caregivers [128–129]. Caregivers can also turn to navigators and spiritual care specialists for meaningful support.

Navigators

Patient navigators have become increasingly relevant in oncology, especially for older adults and their caregivers facing challenges associated with anticancer treatments and with identifying and accessing age-appropriate services to optimize care [130]. Registered nurses are most suited for the role, although social workers, or a trained peer or lay navigators may also take over this role [131]. Navigators are expected to address a high level of complexity, including using knowledge of frailty and the aging process, being trained in assessing and managing chronic conditions, as well as being embedded in an interdisciplinary team [132]. An important task for navigators is linking adults to services that address functional decline [133–134]. These might include referral to occupational therapy, social work, and home nursing support.

Spiritual Care Specialists

Providing spiritual support is critical for the overall well-being and functioning of older adults. Participation in religious activity predicts higher self-rated health [135], better physical functioning [136–137], and less distress [138]. Furthermore, spiritual beliefs may help older adults cope with the impact of the disease on their physical and emotional functioning [136, 139]. Medical and psychosocial support services may support positive spiritual coping efforts, identify individuals for whom negative spiritual coping or distress is present, and assist them in resolving any underlying distress [140–141].

Conclusions

Preservation of functional status is the cornerstone of geriatric care and serves as an indicator of general well-being. As summarized in this review, a decline in function increases the risk of healthcare utilization, worsens quality of life, reduces independence, and increases risk of mortality. To improve health among older adults with cancer, the interprofessional team should proactively monitor their functional abilities and, when needed, arrange for therapeutic interventions that support their functioning and overall well-being.