circadian rhythms, timing of meals and chemo for best effect

[Lani]

Timed Meals and Chemo May Boost Anti-Cancer Therapy


By Megan Rauscher

NEW YORK (Reuters Health) Apr 27 - A team of scientists has demonstrated, for the first time to their knowledge, endogenous circadian rhythmicity in a primary tumor. The discovery might open up new treatment approaches to chronomodulated therapy -- adjusting the temporal pattern of drug delivery to improve the toxic-therapeutic ratio.

The team's studies also suggest that tumor rhythms are sensitive to temporal changes in feeding. "Perhaps by combining chronotherapy with treatments (such as restricted feeding) that can manipulate the phase of the tumor and the host rhythms, the benefits of this treatment approach can be further enhanced," lead scientist Dr. Alec J. Davidson told Reuters Health.

Using transgenic rats, Dr. Davidson, from the Morehouse School of Medicine in Atlanta and colleagues at the University of Virginia in Charlottesville, studied expression patterns of the circadian clock gene (Period 1) in hepatocellular carcinoma and adjacent normal liver tissue.

"This animal's tissues express firefly luciferase in proportion to Per1 gene expression, allowing us to measure molecular rhythms by merely recording light emission with very sensitive detectors," Dr. Davidson explained.

"This comparison revealed not only alterations in the tumor rhythms -- the clock ran faster in the isolated tumor than in healthy liver tissue -- but also that a robust clock still exists in the tumor," Dr. Davidson said.

To study the effects of restricted feeding on the circadian rhythms of liver tumors, hepatoma-bearing rats were fed ad libitum, or a single small meal at night, or the same meal during the day.

"Temporally restricting food availability to either day or night altered the phase of the rhythms in both healthy and malignant tissue," the scientists report in the April 1st issue of the International Journal of Cancer. However, the tumors were much less sensitive to the restricted feeding signal "resulting in markedly different phase relationships between host and tumor tissue as a function of mealtime."

In the night-fed rats, the tumors rhythms peaked earlier than the healthy liver, and in the day-fed rats, the tumors peaked later than the healthy liver.

"Because circadian clocks are known to modulate the sensitivity of many therapeutic cytotoxic targets, controlling meal timing might be used to increase the efficacy of treatment," the authors suggest. "Specifically, meal and treatment schedules could be designed to take advantage of coincident times of greatest tumor sensitivity and lowest sensitivity of host tissue damage."

Int J Cancer 2006;118:1623-1627.

[Cathya]

Lani;

I have heard of bacteria having biological clocks but never thought of cancer. It's an interesting thought.

Cathy

[Lani]

I have read that tumors grow more at certain times of the day and at certain stages of the menstrual cycle, in fact that Ki67 levels in a tumor can vary by what phase of the menstrual cycle a woman is in when the tumor is removed.

There is so much more to know!
Lani

[Cathya]

There certainly is! Thinking way outside the box, just as your article did, and thinking of restricted eating......over the years I have water fasted a few times and found it to be very healing. My first fast washed out whatever was blocking my tubes and after ten years of trying I got pregnant immediately afterward....so you can see I am a believer in the body's power to heal itself. The last time I fasted...about 6 or 7 years ago, unlike the other times it was a very painful experience. I was in agony. I thought this was because I was older and having a more difficult time expelling the toxins. Now I think that I likely already had at least a few cancer cells and when I started my fast I initiated a battle that I was losing from the get go....although I wonder what would have happened if I had had a few months and the strength to hang in there til the end of a natural fast. My initial reading lately has suggested that fasting is not useful for cancer so I have put it out of my mind....but the body CAN heal itself....or has the power to do so. I think once cancer has set in we need to add something (like herceptin or whatever) to the mix but you are so right....there is so much to learn.

Cathy