Abstract P1-09-11: Objective markers of fatigue in women undergoing adjuvant chemotherapy for breast cancer
Authors: Behrendt Carolyn , Waliany Sarah , Frankel Paul , Patel Sunita , Mortimer Joanne 
Published: May 2015

Abstract
Background. In breast cancer patients, fatigue is a leading detriment to quality of life. Objective markers of fatigue are needed to advance research into its treatment and prevention. To that end, we evaluated physical and neurocognitive tests as potential markers of fatigue before and after chemotherapy.
Methods. Women about to begin adjuvant chemotherapy for breast cancer were studied prospectively. Before and after chemotherapy, subjects were assessed on self-reported fatigue (Brief Fatigue Inventory, BFI), depression (CES-D), Pittsburgh Sleep Quality Index, body mass index (BMI), and 18 objective measurements: grip strength in dominant and nondominant hands, 6-minute walk, daily total energy expenditure (TEE) per accelerometer averaged over 1 week, and examiner-administered neurocognitive tests: grooved peg board in dominant and nondominant hands; digit symbol coding and symbol search (Wechsler Adult Intelligence Scale, 4th edition); 2 trail-making, 4 color-word interference, and 4 verbal fluency tests (Delis-Kaplan Executive Functioning System, D-KEFS). Due to correlation between markers, each was evaluated individually as a continuous variable in generalized linear models of BFI. Models used generalized estimating equations with independent correlation matrix. Covariates (age, tumor stage, BMI) and potential interaction between marker and time of assessment (pre- or post-chemotherapy) were considered.
Results. Of subjects enrolled (n=28), 3 withdrew before wearing the device; these were similar to evaluable subjects except for lower scores on digit symbol (p&lt;0.002) and color inhibition (p&lt;0.02). Another subject (a vigorous athlete age 36) was excluded, because she alone did not experience the primary endpoint (fatigue) at either assessment. Thus, the final sample was n=24 (age 50.3+9.5 years). BFI before chemotherapy was median 1.17 (interquartile range 0.33-3.50) and increased +2.11(+2.64) after chemotherapy. Worse sleep quality (p=0.003), greater grip strength in dominant (p=0.001) and nondominant hand (p=0.003), and higher daily TEE (p=0.03) were each associated with BFI after chemotherapy but not before. In contrast, better performance on each of 4 neurocognitive tests (D-KEFS color patch p=0.04, color word p&lt;0.001, switch correlation p&lt;0.001, switch accuracy p&lt;0.001) was inversely associated with BFI before chemotherapy but not afterwards. Other neurocognitive tests and 6-minute walk were not associated with BFI. Only depression score was associated with BFI before (p&lt;0.0001) and after (p&lt;0.0001) chemotherapy; moreover, a given level of depression was associated with greater BFI after chemotherapy than before (interaction with time, p&lt;0.0001). None of the models fit BFI data better when covariates were taken into account or when markers were considered simultaneously.
Conclusions. Unlike neurocognitive tests, certain physical measures (grip strength in either hand, TEE, sleep quality) can serve as marker of the fatigue that follows cancer treatment. Grip strength has the advantage of being both objective and efficient to measure. No marker currently studied is suitable for comparing fatigue pre- versus post-chemotherapy, however.
Citation Format: Carolyn Behrendt, Sarah Waliany, Paul Frankel, Sunita Patel, Joanne Mortimer. Objective markers of fatigue in women undergoing adjuvant chemotherapy for breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-09-11.