A recent study suggests that cancer patients receiving immunotherapy in the morning may experience significantly longer survival compared to those treated in the afternoon. Researchers at The Christie hospital in Manchester examined data from 2,631 patients with various advanced cancers who underwent immunotherapy between 2018 and 2023.

The investigation found that patients receiving most of their treatments in the morning survived for a median of 21.4 months, compared with 13.1 months for those treated predominantly in the afternoon. This difference amounts to a median survival increase of over eight months, or approximately 63 percent longer. The largest survival benefits were observed among patients with skin and lung cancers.

The study team is exploring the role of circadian rhythms—natural physiological cycles regulated by the body’s internal clock—in influencing immune system activity and response to treatment. Previous, smaller studies have indicated that immune responses and treatment efficacy can vary depending on the time of day, affecting areas such as vaccination and cancer therapy.

Prof. Paul Lorigan, one of the study’s authors, noted that the findings “appear to be a signal worth investigating further.” The research, published in the British Journal of Cancer, raises the possibility that adjusting treatment schedules to earlier in the day could improve patient outcomes without the need for new drugs or additional therapies.

While the results are promising, further research is needed to confirm these associations and to better understand the underlying biological mechanisms that may contribute to time-of-day differences in immunotherapy effectiveness. If validated, this approach could represent a simple and cost-effective strategy to enhance cancer treatment outcomes.