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Radioreceptor therapy (DOTATOC)
Lu-177-DOTATOC- or Y-90-DOTATOC-therapy
PRRT (peptide radio-receptor therapy) of somatostatin receptor-positive malignant tumours by using a peptide DOTATOC labelled with the radioactive beta emitter Yttrium-90 or Lutetium-177.
Prof. R. P. Baum performed most of the cancer therapies with Lu177-DOTATOC in neuroendocrine tumours across Germany.
1. Which tumours can be treated?
It is possible to treat tumours and metastases that have an increased somatostatin receptor occupancy on the surface of the cancer cell. This receptor occupation is detected by DOTATOC PET/CT, a necessary preliminary examination, which is performed previously in the practice. PET/CT allows to accurately determine the number of docking sites for subsequent therapy on tumour cells/metastases by using so-called uptake values (SUV) and thus to predict whether Lu177-DOTATOC or Y90-DOTATOC therapy would be useful and if the therapy can be successful: THERANOSTICS principle – irradiation is targeted to what is previously visible on PET/CT.
2. Mode of action of Lu-177/Y-90-DOTATOC therapy
PRRT is used for nuclear medicine treatment of somatostatin receptor-positive metastases or tumour recurrences, which no longer respond to other treatments. For this purpose, a molecule labelled with the beta emitter Lu-177 or Y-90 is used. The range of the beta emitter Lutetium-177, for example, is about 2 mm in tissue. Very large tumours can also be treated, since the molecule penetrates almost any tumour depth. Due to the short range, healthy tissue can be spared as far as possible. The molecule labelled with the beta emitter is applied into a vein of the arm and accumulates very quickly in the metastases or tumour recurrences which have been previously detected by DOTATOC PET/CT, as well as it accumulates in the primary tumour – what is previously visible in PET/CT is also irradiated – “we see what we treat”. The therapy effect thus depends on the storage intensity in the PET/CT. The therapy emitter destroys the DNA of the tumour cells, which should slow down the growth of the tumour or cause it to regress.
3. Course of therapy
The duration of inpatient admission to DKD Helios Hospital is approximately 3-4 days. Unfortunately, you are not allowed to receive visitors or leave the ward during your inpatient stay, for reasons of radiation protection. However, you will have regular contact with doctors, nursing staff and, of course, your fellow patients. You will also have access to telephone, television, and Internet connection (WLAN).
In advance to the therapy, necessary examinations (laboratory control, whole-body DOTATOC-PET/CT, possibly kidney- or salivary gland scintigraphy, sonography) are performed. The results of the examination are discussed in detail before the treatment.
It is necessary to drink at least 1.5 litres of liquid, on the therapy day, to keep radiation exposure as low as possible (accelerated excretion).
The therapy substance is administered intravenously via an arm vein what takes only a few minutes. The excess therapy substance not docked to the metastases/tumours is predominantly excreted renally. Infusion therapy (parenteral fluid administration) is given to reduce renal burden. It is extremely rare that patients experienced nausea after therapy.
After injection of the therapy substance, the patient must remain on the therapy ward for at least 48 hours (this is a legal requirement, that cannot be negotiated).
The control of the accumulation intensity in the metastases as well as measurements of the degradation of the therapy substance in the rest of the body are carried out in the nuclear medicine practice as scintigraphic whole-body images as well as with SPECT/CT (tomography/slice examination) of the tumour regions.
The therapy is usually repeated several times at intervals of 3-4 months. Before a new therapy course, a DOTATOC-PET/CT is usually performed to monitor the success.
4. Potential side effects
The number of red blood cells (erythrocytes), platelets (thrombocytes) and white blood cells (leukocytes) may decrease. Therefore, the blood count must be checked at certain intervals after therapy. Even after repeated therapy, there is usually no restriction of renal function, renal function is monitored. Due to accumulation in the lacrimal and salivary glands, radiogenic sialadenitis (dry mouth) may occur (this has been observed rarely). Allergic reactions may (theoretically) occur during administration (never observed to date). Long-term side effects or harmful long-term effects have not occurred/are not known so far.
5. The therapy cannot be used in the following diseases:
– Acute infections with fever
– Severe bone marrow insufficiency
– High-grade renal insufficiency
– Myocardial infarction within the last 6 weeks
– Rapidly progressive second malignancies
Contact: Prof. Dr. med. Richard P. Baum, CURANOSTICUM Wiesbaden-Frankfurt
Email: baum@curanosticum.de