Cancer scientists have long been interested in how and why tumors grow and spread. Now, a group at the Weizmann Institute of Science has found that tumors might grow more quickly at night, meaning that it might be more efficient to give chemotherapy during the night rather than during daytime.
"It could mean that some treatments should be done during the night," Yehoshua Enuka, one of the authors of the report told The Media Line. "It could also lead to a better understanding of the exact biological and molecular mechanism that governs the process of tumor progression."
The findings, which were published in Nature Communications, were done on gastric tumors in mice and the experiment has not been done yet on human subjects.
In the case of the mice, which are more active during the night and sleep during the day, the tumors grew more quickly during the day. The hypothesis is that in the case of people, the tumors will grow faster at night than during the day. It would therefore be more effective to give chemotherapy at night.
Non-scientists might question how much validity a study on mice could have on human cancer, but scientists say humans are more similar to mice than we might think.
"There’s a concept of a model organism in biology," Don Katcoff of the Faculty of Life Sciences at Bar-Ilan University told The Media Line. "The physiology is similar and many of the same rules apply."
He also said the findings that were published do seem to be breaking new ground.
"They found that the tumors became smaller if chemotherapy was given to the mice during the daytime, which is equivalent to our night," he said. "They found that it the difference was statistically significant, but there is a conglomerate of factors that go into deciding how much chemotherapy to give and what kinds of compounds to use."
He suggested it was likely that a similar trial would be conducted with people to see if the findings are replicated.
Dr. Matia Lauriola of Bologna University in Italy, the primary author of the paper, said the new ground broken has to do with the interaction between tumor growth and the hormone receptor factor. The receptors are protein molecules found either on the cell’s surface or within cells.
The research focused on two specific receptors – the epidermal growth factor receptor, EGFR, helps cells, including cancer cells, grow and migrate. The second receptor binds to a steroid hormone called a glucocorticoid (GC), similar to cortisol. This is often called the “stress hormone” because its levels rise in stressful situations.
"Nobody looked at the interaction between different factors in these cases," Lauriola told The Media Line. "We are the first to look at these interactions and we think it is important for the understanding of the mechanism that has been important for tumor growth."
The scientists gave a breast cancer drug, Lapatinib, to mice with cancer. The drug is meant to inhibit EGFR, to prevent the growth of the cancer cells. They were more effective during the day, when the mice were sleeping, than at night.
Yehoshua Enuka of the Weizmann Institute says that the research could help scientists understand how tumors grow.
"It sheds new light on tumor progression," he said. "If we know it progresses more at night, we know there are different biological mechanisms that are more prevalent during the night. The cortisol seems to block the biological processes that enhance the tumor."
Article written by Linda Gradstein.
Reported with permission of The Media Line.