Study: Female Patients Undergoing Afternoon Cancer Treatment Have Better Outcomes

The biological processes affected by the body's circadian rhythm can be used to identify the optimal time for patients to receive cancer treatment. vetre/shutterstock

A study from South Korea showed that female patients who underwent cancer treatments in the afternoon had better outcomes than those who were treated in the morning. Their five-year mortality rate was reduced by 12.5 times.

Results of the “Temporal Anticancer Therapy” study were released by Kim Jae-kyung, Research Director of the Center for Mathematical and Computational Sciences at the Institute for Basic Science (IBS), and Professor of Mathematical Sciences at KAIST, and Professor Youngil Koh of the Department of Hematology and Oncology at Seoul National University Hospital (SNUH), on Dec. 15.

The study of 210 patients with diffuse large B-cell lymphoma (a type of leukemia) showed that females who received cancer treatments in the afternoon had better outcomes than those treated in the morning. Researchers noted that women’s white blood cell count was lower in the morning and higher in the afternoon; but men did not have this variation. Time of treatment did not affect the outcome of the male patients in the study.

“ ... in the case of female patients who received afternoon treatment, the mortality rate after 60 months was reduced by 12.5 times compared to patients who received morning treatment. Only 2 percent of patients treated in the afternoon died, compared to 25 percent of patients treated in the morning.”

Cell proliferation and cellular differentiation, are regulated by the 24-hour biological clock. The effectiveness and side effects of anticancer drugs, were observed to be different according to the time the women received the medication. Therefore, time-specific cancer treatment, or chronotherapy, can be used to determine the best time to undergo cancer treatment in order to optimize pharmacological efficacy and reduce side-effects.

In 2019, Kim’s research team invented a process it calls “adaptive chronotherapy” to identify the best time to take medication in a day, and analyzed the efficacy of a new medication for treating sleep disorders through mathematical models.

The research showed that the mortality rate for patients who received afternoon treatments was only two percent, while it was 25 percent for patients who received treatments in the morning.

The progression-free survival for female patients who received treatments in the afternoon was also 2.8 times higher than those patients who received treatments in the morning. The condition of about 37 percent of the patients who received morning treatments deteriorated, while only 13 percent of the patients who received afternoon treatments deteriorated.

Progression-free survival refers to the period of time a patient starts receiving treatment to when the cancer starts to proliferate.

In addition, a higher proportion of patients who received treatments in the morning experienced fewer side effects such as, leukopenia.

The team collected and analyzed 14,000 blood samples from the health care center of SNUH, and the result showed that the number of white blood cells in the average female dropped in the morning and rose in the afternoon.

This shows that the functions of bone marrow in females increase or decrease cyclically in 24 hours. While for males, there is no significant change in the number of white blood cells and speed of bone marrow cell proliferation. Hence, there was no obvious difference in the effectiveness between morning treatments and afternoon treatments observed in the male patients.

‘Through the complete control on other variables in the large scale follow up study, the project verified again the conclusion of this study, and also further confirmed the research on whether other cancers have similar effects. I hope that this study could facilitate greatly the introduction of the time-specific cancer treatments to the hospitals in South Korea,” Professor Koh said.

‘The time of the biological clock may have a key difference according to the individuals’ sleeping patterns. Therefore the technology of deducing the biological clock from sleeping patterns is being developed currently,” said Kim. “Through this technology, tailor-made time-specific cancer treatment will be developed eventually.”

The findings of the study were published in JCI Insight, the academic journal of the American Society for Clinical Investigation on Dec. 13.