A new review paper, which takes a broad view of research developments in a field, has suggested that the circadian rhythm - the cycle that aligns an organism's physiology with the cycle of the day - can influence the diagnosis, development, and treatment of cancer. This report has outlined various ways that the process of testing patients for cancer and the timing of therapeutic applications could boost their accuracy and success. The work has been published in Trends in Cell Biology.
The circadian rhythm regulates many cellular functions that have been connected to the progression of cancer, and there may be ways to exploit those connections to fight cancer metastasis, noted the study authors. The circadian rhythm coordinates a variety of different physiological processes, and can impact gene expression, cell repair, and the function of the immune system.
Disruptions in the circadian rhythm in people, such as individuals who do shift work or have erratic sleep patterns, have been associated with detrimental health effects and an increase in the likelihood of certain diseases. Circadian rhythms have also been shown to affect tumor growth and the progression and metastasis of cancer.
Cancer is deadliest when it metastasizes; when cells from the primary site of cancer break away, migrate to other parts of the body and cause cancer in other locations. Research has shown that the movement of cells away from that primary site follows a daily cyclical pattern, and these cycles vary depending on the type of cancer. Breast cancer, for example, is most likely to metastasize at night, while prostate cancer or multiple myeloma are more likely to metastasize at other times.
In this study, the researchers noted that we could leverage that information to optimize chemotherapy and immunotherapy treatments, an approach known as chronotherapy.
Clinical studies have indicated that the severity of treatment side effects can be reduced with chronotherapy, while also impacting treatment effectiveness. We should be using this knowledge to a patient's advantage, noted the study authors.
A recent report found that when melanoma patients got their immunotherapy drugs before 4:30 PM, they were almost twice as likely to survive compared to patients who were treated later in the day. The optimal time of treatment would depend on the type of cancer and therapy being used, and could also be affected by patient characteristics, including their genetic background.
The diagnosis of cancer could also be more accurate with a timed approach, because cancer cells generate proteins at different rates during the day. Some of those differentially expressed proteins are also used as diagnostic markers. The chance of a misdiagnosis might be reduced by collecting and testing patient samples whenever these proteins are known reach their highest levels during the day.
Sources: Cell Press, Trends in Cell Biology