Time influences how well chemo drugs could help fight cancer: study

By Mark Waghorn via SWNS

The time chemotherapy drugs are administered influences how well they fight cancer, according to new research.

Some work better during the day and others at night, scientists said.

The phenomenon could lead to personalized treatments. It also has implications for tumor growth - and diagnosis.

Most living organisms – animals, plants, fungi and even bacteria – have an internal, or circadian, clock.

It orchestrates the biochemical, physiological and behavioral functions in each cell according to a 24-hour cycle.

The rhythms don't just govern sleeping schedules. They also impact development of disease.

Corresponding author Professor Nicola Aceto, of the Swiss Federal Institute of Technology, Zurich, said: "The circadian rhythm governs most of the cellular functions implicated in cancer progression, and therefore its exploitation opens new promising directions in the fight against metastasis."

Stopping spread, or metastasis, is the 'Holy Grail' of cancer research - turning it from a fatal to a chronic disease.

Our circadian rhythms help synchronize gene expression, immune function and cell repair.

Disruptions by erratic sleep, jet lag or shift work have been linked to life-threatening illnesses - including cancer.

They can also fuel the migration of cells - leading to the formation of secondary tumors that often kill.

For the process to occur, cells need to break away from the primary site, enter the bloodstream and infiltrate another organ.

Studies have shown the rate at which this happens oscillates throughout the day. But the timing differs between cancer types.

For example, breast cancer is more likely to spread at night while we are asleep, whereas prostate cancer and multiple myeloma peak at other points during the day.

Leveraging this information would enable chemo and immunotherapies to be administered at the optimal hour - a practice known as chronotherapy.

Prof. Aceto said: "Circadian rhythm-based metastasis formation should be seen as an opportunity to intervene in the most timely and effective way.

"Chronotherapy holds promise to be a valuable alternative treatment option in the fight against cancer."

Clinical trials have shown chronotherapy also reduces severity of side effects experienced by patients - and impacts success.

The researchers cited a recent study in which survival rates almost doubled in melanoma patients given immunotherapeutic drugs before 4:30 p.m.

This was compared to those who received the treatment later in the day.

The best timing varies for different cancer types and therapeutics. The clinical benefits of chronotherapy might also be affected by factors such as the patient's sex and genetic background.

Knowledge of the circadian rhythms of cancer cells could also aid cancer diagnosis. Cancer cells produce proteins at different rates throughout the day.

Some of these proteins are used as diagnostic molecular markers. We could decrease the chances of misdiagnosing a patient by collecting and testing biopsies at the time of the day when the concentration of these proteins is highest.

Added Dr. Aceto: "More mechanistic understanding of these processes will be required to fully unleash its potential on the clinical side.

"Defining the circadian-rhythm-controlled timing of proliferation and release of circulating tumor cells into the bloodstream in additional cancer types may help to identify the optimal time window for therapy administration."

The study is in the journal Cell Biology.