Fatigue, Sleep and Urinary Symptoms Affect Cognition in Prostate Cancer

Managing fatigue, urinary issues and depression is essential for improving cognitive function in patients receiving radiation therapy for prostate cancer, though more research is needed to confirm these benefits, according to study findings presented at the 50th Annual Oncology Nursing Society Congress.

A total of 103 patients participated in this study. Cognitive function, as measured by the CogPCI, was significantly associated with fatigue, sleep quality and age. Specifically, higher fatigue (FACIT-Fatigue), worse sleep (PSQI) and younger age were linked to worse cognitive scores. Fatigue was also significantly influenced by depression symptoms (CES-D). Prostate symptoms (IPSS) and sleep quality were nearly significant predictors of fatigue. Depression, prostate symptoms and sleep indirectly affected cognitive function through their impact on fatigue. Overall, this model explained 50.2% of the variance in cognitive function scores.

“This study suggests that oncology nurses should address sleep disorders, urinary system issues and depletion to enhance cognitive function in patients receiving radiotherapy for prostate cancer,” said Mika Miyashita during the presentation of the study findings. “Further research with interventions is needed to demonstrate improvement in cognitive impairment through the alleviation of affecting symptoms.”

Miyashita is a researcher and teacher at Kyoto University in Kyoto, Japan, where she focuses on cancer-related cognitive dysfunction.

Radiation therapy uses high-energy rays — like x-rays, gamma rays or protons — to kill cancer cells and shrink tumors, according to the National Cancer Institute. It can be delivered in different ways. The most common is external-beam radiation, where a machine aims radiation at the cancer from outside the body. In some cases, radioactive material is placed inside the body, close to the cancer — this is called internal radiation or brachytherapy.

Fatigue during radiation therapy can feel like an overwhelming sense of tiredness that doesn’t go away with rest. It may make everyday tasks feel harder and leave a person feeling weak, heavy, or drained. Some people may also notice trouble focusing, memory lapses, or changes in mood. This kind of fatigue can be caused by the cancer itself or by the treatment and may continue even after radiation therapy is finished. It’s different from typical tiredness and can affect both the body and the mind.

Methods and Trial Design

This study followed older adults with prostate cancer through their course of radiation therapy at the Hiroshima High-Precision Radiotherapy Cancer Center in Japan. To be eligible, patients had to be 65 or older and receiving external beam radiation therapy (74 to 78 Gy over 37 to 39 treatments). Patients were not included if they had been diagnosed with dementia, were already experiencing cognitive symptoms, or couldn’t complete the questionnaire on their own.

The study was approved by the institutional review boards at Hiroshima University. During outpatient visits, physicians gave flyers to potential participants identified by the research team. Those who showed interest received a full explanation of the study and gave written consent before beginning treatment.

Participants completed surveys at three timepoints: before starting radiation therapy (T1), after receiving 30 Gy (T2) and at the end of treatment (T3). The goal was to understand how fatigue might influence how patients perceived their memory and thinking during treatment. Cognitive function was measured with the FACT-Cog (CogPCI subscale), and fatigue was assessed with the FACIT-Fatigue scale. Urinary symptoms, depression and sleep quality were measured with the IPSS, CES-D and PSQI, respectively.

Better scores on the cognitive and fatigue scales reflected better well-being, while higher scores on the other tools indicated more severe symptoms.

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