By Dr YLM
MY mother-in-law was diagnosed with lung cancer. She was devastated, but the doctor persuaded her to go for radiotherapy. what is radiotherapy?
Radiotherapy has nothing to do with radio waves. the “radio” here means “radiation”. It’s actually short for radiation therapy, which uses high-energy radiation targeted at the area where the cancer is. These waves will then shrink or kill the tumour cells.
Radiotherapy may be used alone or in combination with surgery, chemotherapy, or both. These days, the thinking is to attack the cancer as aggressively as possible so that you can kill the tumour cells with one mighty blow as fast as possible. this is to prevent recurrence.
Very likely, even when the cancer is at an early stage, radiotherapy is likely to be used in combination with surgery and a dose of chemotherapy and targeted therapies.
Radiotherapy is also given even when the cancer is incurable. Here, it is to relieve the symptoms and suffering at the final stages, as in allowing the patient to breathe properly, eat and drink, or to relieve pain.
What type of radiation waves are used? is it something like a microwave?
The waves used are x-rays, gamma rays, and charged particles. These are delivered by a machine which can be placed outside your body, or through radioactive material placed inside your body near the cancer cells.
The type of radiotherapy placed outside the body is called external-beam radiation therapy.
The one involving the radioactive material placed inside your body is called internal radiation therapy or brachytherapy. the radioactive isotope material is planted as a “seed” through a needle or catheter in a surgically created hole near the tumour. the isotope decays naturally, no longer giving radiation when it is spent, and will cause no harm if left in the body.
There is also systemic radiation therapy where radioactive substances such as radioactive iodine is injected in your blood or given orally, where they travel to the organ where the cancer is to kill the cancer cells.
An example of this treatment involves thyroid cancer. the radioactive iodine will go directly to the thyroid cells, and be naturally taken up.
I don’t understand how radiation can kill cancer cells.
Radiation can kill a whole lot more living cells other than cancer cells! Radiation damages the DNA of the cancer cells, or creates charged particles called free radicals within them, which in turn damages the DNA of the cancer cells.
The cancer cells with the damaged DNA then cannot divide properly, and they stop reproducing themselves, so to speak. the cancer shrinks and the dead cells are broken down and eliminated by our own body’s metabolism, just like it is done for our normal dead cells.
How does radiotherapy kill only the cancer cells and avoid our normal cells?
Most radiotherapy don’t. There are sophisticated machines such as the Cyberknife, which attempts to deliver the radiation waves as close to the cancer margins as possible without destroying normal tissue around it. but by and large, the normal tissue areas around the area of cancer treatment may be affected.
The normal cells that may be affected during the course of treatment is taken into account while planning for the radiotherapy. Normal cells can receive a certain amount of radiation safely. There is also such a thing as a safe lifetime dose, which means a certain part of your body can only receive a certain amount of radiation safely for your entire life!
Radiation doses are in units called Gray (Gy), which is a measure of the amount of radiation absorbed by 1kg of human tissue. different doses of radiation are needed to kill different types of cancer.
Of our normal tissues that are most easily damaged by radiation, our reproductive organs (ovaries, testicles) are the foremost.
My mother-in-law was told by her oncologist that she will get radiation therapy and chemotherapy before surgery. is this normal?
This is called neo-adjuvant therapy. it is given to shrink the tumour so it can be removed easier by surgery and be less likely to return after surgery.
Sometimes, radiation therapy is given during the surgery.
Okay, let’s talk about the thing most people are afraid of when they hear about radiotherapy: side effects. what sort of side effects can my mother-in-law expect?
There are early and late side effects. During radiotherapy, the rapidly dividing normal cells around the area being treated are affected.
These include your skin, hair, salivary glands, and bladder. So you may experience skin irritation or damage to your salivary glands, hair loss, or even urinary problems, depending on the area being irradiated, of course.
These side effects disappear when the treatment ends. There are drugs, however, that protect the normal tissues from being harmed, called radioprotectors.
You may also experience nausea and vomiting if your gut is being irradiated, and fatigue.
Later side effects include scarring, damage to your bowels, infertility, memory loss, but very rarely, a second cancer caused by exposure to radiation.
The oncologist will tell you the benefits and the risks, and you can decide for yourself.
Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health advice, computers and entertainment. the information contained in this column is for general educational purposes only. Neither the Star nor the author gives any warranty on accuracy, completeness, functionality, usefulness or other assurances as to such information. the Star and the author disclaim all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
