Patients with lymphoma may experience a continued decline in cognitive function 6 months after receiving chemotherapy, according to a study published in the Journal of the National Cancer Institute.1

The study showed no differences in cognitive function by lymphoma type or treatment regimen, but there were some “paradoxical” differences between the sexes, according to authors of a related editorial.2

The editorialists noted that most studies of cognitive decline among cancer patients have focused on patients with breast cancer and other solid tumors.

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Neuropsychological assessments have shown cognitive decline in 30% to 45% of cancer patients who undergo adjuvant chemotherapy, and roughly half of patients self-report sustained cognitive symptoms related to their cancer or its treatment.2

“There are limited data in patients with hematological malignancies and a lack of studies documenting the longitudinal changes in cognition experienced over the course of treatment for lymphoma,” the editorialists wrote.

Study Methods

For the current study, the researchers analyzed 248 patients, 21 years of age and older, with intermediate or high-grade lymphoma. Most patients had non-Hodgkin lymphoma (n=186), and 39.5% had diffuse large B-cell lymphoma.

The researchers evaluated changes in memory, attention, and executive function at 3 intervals: pre-chemotherapy, post-chemotherapy, and 6 months post-chemotherapy.

The researchers also compared the lymphoma patients to 212 control individuals without cancer. The patient and control groups were well balanced by age, race, ethnicity, cognitive reserve (WRAT-4 reading score), and marital status.

To collect results, the researchers used a multi-tiered testing system. Participants completed computerized tests, paper-based tests, and phone-based assessments after in-person assessments.

Results: Cognitive Decline Over Time

The lymphoma patients displayed more cognitive problems over time when compared with control individuals, both by objective assessment and self-report.

At baseline, there were no significant differences between lymphoma patients and control individuals on tests of memory, attention, and executive function. However, the lymphoma patients did have worse perceived cognitive impairment by self-report.

From baseline to both post-chemotherapy endpoints, the lymphoma patients exhibited more cognitive problems than did control individuals.

The lymphoma patients reported greater perceived cognitive impairment and performed significantly worse on “tests of verbal memory and delayed recall, attention and executive function, and telephone-based category fluency,” according to the researchers.

The editorialists noted that the different testing modalities produced variable results, but phone tests appeared to be the most sensitive, especially at picking up attentional processing.

More research is needed to fully understand why phone tests are so sensitive, said editorialist Joanna Fardell, PhD, a post-doctoral research fellow at the University of New South Wales in Sydney, Australia.

“It may be that phone assessment is more sensitive to difficulties in cognitive function in cancer patients,” she said.

Another possible reason is that phone assessments may be harder because patients may have to navigate distractions in their environment during testing, “but further research really is needed to understand this,” Dr Fardell added.