Endocavitary Radiation TherapyMedical editor Anne-Birgitte Jacobsen MD
Oslo University Hospital
Endocavitary radiation therapy is given in addition to external radiation therapy for curative purposes, or alone for palliative purposes.
The tumor area is radiated using iridium which is programmed to take in pre-defined time intervals in the length of the target volume. The dosage rate and radiation time depend on the age of the iridium which has a half-life of 74 days. The iridium is changed every 3 months.
The effect of the endocavitary technique usually appears later than for stenting, but improves swallowing which will last the rest of the patient's life. The stent may be installed at a later time. Follow-up after radiation treatment is therefore important to assess who needs a stent.
In Norway, the Norwegian Radium Hospital is the only hospital performing endocavitary radiation treatment for esophageal cancer.
- Tumor in the esophagus without tumor component in the stomach
- Curative therapy in conjunction with external radiation treatment
Some CT dosage plans are carried out for endocavitary radiation therapy, but this is not routinely used.
- This type of radiation treatment is a collaboration between anesthesia personnel, surgeon, oncologist, physicist, and radiation therapist. The treatment requires specific radiation equipment.
- Based on the endoscopic description of the tumor and CT, the target volume is defined as 1 cm deep from the esophageal mucosa, and as the endoscopic tumor length plus 1 cm cranial and 1 cm caudal.
- The patient must fast on the day of the treatment.
The patient is sedated.
Endocavitary radiation treatment is performed in two steps. The first radiation step is done in an endoscopy room:
- The tumor's upper and lower borders are localized using a gastroscope and X-ray.
- A hollow applicator is placed in the esophagus with space for the radioactive iridium source .
The patient is immediately moved, in the same position, to the radiation department for the next step:
- The iridium source is programmed for position and time frame to release an even radiation dose to the tumor, plus 1 cm cranial and caudal.
- Each treatment lasts 5-10 minutes depending on the volume of the radiation and age of the iridium.
The treatment is administered in 8 Gy fractions.
- For curative purposes, 1 fraction is administered 1 week after external radiation treatment is concluded.
- For palliative purposes, 3 fractions are administered with 1 week intervals.
Follow-up occurs at the patient's local hospital with individual adjustments of intervals.
Side effects which can occur after endocavitary radiation are:
- problems swallowing
- fibrosis in the esophagus - delayed effect