Month: December 2019

TeachableMedicalNews article 12152019

Teachable moment in classrooms:

1. cellular basis of life chapter – cancer cell formation
2. cellular basis of life chapter – DNA and membrane damage from radiation
3. nervous system chapter – circadian rhythm directed by reticular formation and the hypothalamus
4. integumentary system chapter – stem cells of epidermis in stratum basale

The news item:  This article describes promising research into minimizing radiation toxicity in cancer patients:

Use genetic data to predict the best time of day to give radiotherapy to breast cancer patients, say researchers

A new clinical study led by the University of Leicester and conducted in the HOPE clinical trials facility at Leicester’s Hospitals has revealed the pivotal role that changing the time of day that a patient receives radiotherapy could play in altering radiotherapy toxicity.

The article mentions PER3 and NOCT genes of circadian rhythm, and how they change skin biology, and the adverse response of skin to radiation therapy.

So, Why Do I Care??  Many types of cancers are treated with radiation therapy, bringing the total to over 3 million patients every year in the USA.  While radiation therapy is successful in reducing cancer growth, the treatment has several side effects, called radiation toxicity.  One of those side effects is the thickening and reddening of the skin.  Any approach that reduces the side effects of the treatment will increase the comfort and quality of life of millions of cancer patients.

Plain English, Please!!!

First, let’s talk about radiation therapy. The eradication of the cancer cells in cancer patients can be achieved by surgery, chemotherapy, and by radiation therapy.  The radiation is nothing else but invisible rays that are aimed at the body part that has the cancer; those rays kill the cancer cells by damaging their DNA and the cell membrane. As the radiation comes from a machine, those killer rays must pass through the skin in order to reach cancer inside the body.

Second, let’s talk about skin reaction to radiation.  No surprise that the very rays that destroy cancer cells also damage the skin as the rays are passing through it.  Think about how the rays from the Sun pass through the skin, and cause sunburn.  Cells in the actively growing layer of the skin are damaged most, and that layer has to regenerate to keep the skin functioning.  That regeneration is making the skin red, and thick, painful, cracked, and even bleeding.  This is worse than the dry and cracked skin you get in the winter time.

Third, let’s talk about circadian rhythm.  We feel sleepy at night, and wake up in the morning, because of the daily rhythm directed by our nervous system.  That daily rhythm is called the circadian rhythm.  As it turns out our skin regenerates better at certain times of the day, so the skin regeneration is also moving along a circadian rhythm.  People with specific version of the genes called Per3 and Noct have skin rhythms with better regeneration in the afternoon.  This means that for those patients, identified by genetic analysis, the radiation treatment scheduled for the afternoon will speed up the regeneration, and minimize skin damage.