Cancer is the leading cause of death and a major obstacle to increasing life expectancy in the world.1 According to Global Cancer Statistics 2020,1 there are approximately 19.3 million new cancer cases and 10 million cancer deaths worldwide in 2020, and the global cancer burden is expected to reach 28.4 million in 2040, with a rise of 47% from 2020. Although malignancies would occur in people of all ages, more than two-thirds of new cancer cases are diagnosed among those adults aged 60 years and older.2 With the increasing aging of the population, the cancer burden is anticipated to become heavier among the elderly. This inevitably poses a challenge for cancer specialists to determine the optimal therapeutic regimen for those older patients, a heterogeneous population in terms of comorbidity, disability, physical reserve, and geriatric conditions.3

In an attempt to provide guidance for treatment decisions, two features of geriatrics, namely frailty and the comprehensive geriatric assessment (CGA), are being incorporated into geriatric oncology.3 As one of the most severe global public health challenges, frailty has been regarded as a complex and age-related clinical condition characterized by decreased function across multiple physiological systems, which would induce increased susceptibility to stressors.4 As is reported in several studies, frailty is significantly associated with a higher risk of chemotherapy intolerance,5 postoperative complications, mortality,6 and poor prognosis7 among older patients with cancer. The CGA is a multidimensional and multidisciplinary assessment process to identify and manage older patients that focuses on the patient's medical, psychosocial, and functional domains.8 It has been found to be beneficial to health outcomes for community dwellers, nursing home residents, and hospitalized older patients.9 In geriatric oncology, the CGA can be performed to detect disabilities and geriatric conditions that can conduce to frailty.3 However, it is often time-consuming and impractical to perform a CGA in a ward with limited resources. Currently, there is no global standard assessment instrument for frailty.10 Of note, research has focused on frailty screening methods to identify fit or frail older patients who are suitable to receive standard therapeutic regimens or to undergo a CGA to guide the tailoring of their treatment regimens.3

The Geriatric 8 (G8) questionnaire is a common frailty screening tool designed specifically for older patients with cancer3 and is administered by healthcare professionals in clinical practice.11 The G8 questionnaire, developed by Bellera et al.,12 was first used for screening frailty in 364 older cancer patients. And it presented good sensitivity (85%, 95%CI: 81%-89%) and acceptable specificity (65%, 95%CI: 41%-85%)13 at a threshold of 14 points when using the CGA as a reference standard. As per previous studies, the G8 has been verified to have a strong prognostic value for functional decline,14 overall survival,15,16 and complications17 among older cancer patients. Recently, Cavusoglu et al.18 revealed that the Turkish version of the G8 (T-G8) was a valid and reliable tool for older patients without malignancy in geriatric outpatient clinics. And there was a strong agreement between the T-G8 and CGA in the validity (kappa=0.630, P<0.001) and high inter-rater and intra-rater agreement in the reliability (kappa=0.886 and 0.875, P<0.001, respectively). Nevertheless, it is still necessary to conduct further investigations to explore the use of the T-G8 in older cancer patients, especially the psychometric properties of the T-G8 measured in this population. In addition, Yuk et al.19 translated the G8 into Korean and validated its effectiveness in Korean patients over 70 years old scheduled for cancer surgery. Their findings suggested that the Korean version of the G8 (K-G8) was meaningful and significantly correlated with some evaluation indicators, including patients’ age, comorbidity, and performance status. However, the reliability and validity of the K-G8 need to be further investigated.

To the best of our knowledge, the G8 questionnaire is a practical and helpful tool for screening frailty among older patients with cancer. However, its use in the Chinese population is limited, partly due to a lack of a Chinese version. Therefore, the aims of this study were to: 1) translate and cross-culturally adapt the G8 questionnaire into Chinese through an internationally accepted methodology for Chinese hospitalized older adults with cancer; 2) examine the validity of the Chinese version of the G8 (C-G8), such as content validity, known-group divergent validity based on age, as well as convergent validity with the FRAIL scale; and 3) also evaluate the reliability of the C-G8 in terms of internal consistency and reproducibility in this older population.