Receiving Chemotherapy in the Afternoon Found to Improve Survival in Female Lymphoma Patients

Chronotherapy focuses on the timing of treatment. The goal is to consider circadian rhythms to determine when cancer treatment may be most effective and cause the least harm to the body. A new study finds that the afternoon may be an optimum time for some cancer patients.

Research recently published in JCI Insight, and conducted by researchers from the Institute for Basic Science in South Korea, investigated the impacts of chemotherapy scheduling on lymphoma patients. The idea was to see how the timing influenced treatment outcomes and adverse side effects.


The researchers worked to answer these questions by examining 210 patients at Seoul National University Hospital with diffuse large B-cell lymphoma. They had noticed that one group of these patients had been receiving their treatment – consisting of targeted therapy and chemotherapy – at 8:30 a.m., while the others received theirs at 2:30 p.m.

When examining the patients’ outcomes, they found that female patients who had been treated in the afternoon had a 12.5 times lower mortality rate, along with a 2.8 times reduced incidence of cancer recurrence after five years. The morning group also saw higher rates of chemotherapy side effects like neutropenia, an abnormally low count of white blood cells called neutrophils.

However, the team found that there were not similar trends among the male patients. To try to determine why this was, the researchers studied roughly 14,000 blood samples from the Seoul National University Hospital Health Examination Center. They found that among women, white blood cell counts were usually lower in the morning and higher in the afternoon. They explain that this translates to a higher bone marrow proliferation rate 12 hours later, which would be in the morning. That means that chemotherapy in the morning could lead to more side effects because the bone marrow would actively be producing blood cells at the time.


The researchers say this tendency for morning patients to have a higher rate of side effects meant they often had a 10% reduced dosage, which was a confounding factor in their study.

However, the findings indicate that timing of treatment could be tailored to some patients in an effort to improve their treatment outcomes.

Kim Jae Kyoung, principal investigator and mathematician in the Biomedical Mathematics Group at the Institute for Basic Science, says, “Because the time of the internal circadian clock can vary greatly depending on the individual’s sleep-wake patterns, we are currently developing a technology to estimate the time of the circadian clock from the patient’s sleep pattern. We hope that it can be used to develop an individualized anti-cancer chronotherapy.”


Going forward, the researchers say they plan to conduct a larger follow-up study that controls all confounding factors and determines if there are similar impacts among other types of cancer patients.

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