Your cancer

Living with the disease

Radiation Therapy

What is it ?

Radiation therapy, often abbreviated as RT, RTx, or XRT (and sometimes referred to as Radiotherapy,) is a cancer therapy using the properties of ionizing radiation against tumor cells. This radiation causes DNA damage to the tumor cells. If healthy cells, which cannot be completely spared the harm caused by the radiation, can repair their DNA, this leaves the tumor cells to be more vulnerable. The effect of radiation therapy is limited to the specific location of the tumor cells,not unlike a surgical procedure, and may be synergistic with other treatments, including chemotherapy.


Radiation therapy treatment involves early, complex and technical preparation by oncology-radiation therapists and medical physicists. Depending on the medical indication and the specific organ, the doctor will prescribe a highly specific treatment (e.g., type/dose of radiation and number of sessions).

A centering scan is performed before any treatment to precisely determine the location and volume/mass of the tumor to be treated. Computer simulations are then done to calculate how to deliver the precise dose to the exact location while sparing harm as much as possible to the patient’s otherwise healthy organs and tissue. As such, each treatment is therefore specifically adapted to each patient.

Once the treatment plan is determined, an implementation procedure is conducted during the first session to determine the exact position for this and future treatments. To ensure absolute accuracy during each treatment session, tracking devices or methods (e.g., felt-tip markings or tattoos) as well as positioning tools (e.g., face mask, blocking materials) may be used.

Most often, the treatment is administered for five sessions per week. Each session lasts approximately 10 minutes, and the radiation itself is invisible, odorless, and painless.

Specific subtypes of radiation therapy include :

Brachytherapy where the radioactive source is transiently implanted in contact with the tumor itself.
Stereotaxic radiation therapy in which is a high dosage, highly-focused radiation therapy reserved for small lesions. In such instances, fewer sessions are typically necessary but over a longer duration (e.g., approximately 45 minutes).

Side Effects

Any adverse effects of radiation therapy are typically limited to the treated area, but this may also affect all the tissues the radiation passes through.

Most side effects are acute, appearing after about a week of treatment and last a few days to a few weeks after radiation therapy has been completed.

The most common side effect is radiodermatitis
(similar to sunburn),
but this is dependent on the specific organ
being treated.

More rarely, some side effects may persist
or appear later and can be chronic.
Again, this is dependent upon the specific organ/region and the treatment intensity.

To prevent and/or manage these side effects effectively :

You will be questioned regularly by
radiotherapy technicians at the treatment station
You will be seen in consultation regularly
(e.g., once a week, or more if necessary)
by an oncology-radiation therapist, who will look for side effects
and offer symptomatic treatment if necessary.

In some cases, it may be necessary to postpone or stop the treatment.


Radiation therapy can be used at different stages of the cancer :

As curative treatment

Radiation therapy alone can destroy the tumor, for example in some lung tumors, or in combination with an other chemotherapy, for example in cervical cancer.

As adjuvant treatment

Combined with radical local treatment (e.g., surgery) to reduce the risk of localized recurrence, for example after a tumorectomie.

As palliative treatment

In advanced diseases, to treat painful tumor lesions (bone metastases or lymph nodes).