Machine-assisted transcript of the original 2023 recording, edited for readability and checked against two transcription passes. An unclear isotope number is marked with its timestamp; please refer to the original recording. Treatment statements and centre activity figures are those of the speaker at that time.
PRRT, or radiopeptide therapy for neuroendocrine tumours, has become the standard of care for the treatment of low to intermediate grade neuroendocrine tumours. PRRT is actually administering a radioisotope which targets the somatostatin receptors which are expressed on these patients of well-differentiated neuroendocrine tumours. And by actually targeting these somatostatin receptors, we are able to deliver a very high dose of radioisotopes, which goes and attaches to the tumour cells without damaging the surrounding cells.
Now, this becomes very important because many patients with neuroendocrine tumours have got large volume metastatic disease in the liver. We need isotopes which will go and target the tumour without damaging the normal liver, or in patients who have got skeletal metastasis, we need isotopes which will go and target the tumour without damaging the surrounding bone marrow. And by using PRRT we are able to do exactly this, and that is the reason why PRRT is often called the magic bullet therapy, because these radiopeptides go and attach directly to the tumour cells without actually causing any kind of harm to the surrounding structures.
PRRT can be done with various radioisotopes. The beta-emitting lutetium is the most common radioisotope. Yttrium-90, another beta-emitting radioisotope, has got a higher energy than lutetium and can be used to target bigger tumours or patients who have got larger metastatic disease. And now there is a growing body of evidence which says that PRRT can also be done with the novel alpha-emitting radioisotopes like bismuth-213 or actinium [isotope number unclear, 2:22]. The alpha-emitting radioisotopes have got an energy which is almost five times that of the beta-emitting radioisotopes, and thus their cell kill is far, far more than the beta-emitting radioisotopes.
PRRT is given in fractions. Typically every patient receives about four to six fractions of PRRT. Each fraction entails an injection of the radiopeptide, which may be given intravenously or intra-arterially. There is a gap of about three months between each fraction, and the number of fractions depends on the volume of disease and the response which a patient has to the various tumours.
Administering radioisotopes intra-arterially allows us to actually deliver the radiopeptides directly at the site of the tumour, most commonly into the liver. Sometimes even in certain other sites which have got a feeding artery, we can administer the radioisotope directly into the tumour, thereby improving its efficacy.
At our centre we treat about 250 to 300 new patients of neuroendocrine tumour every year. Being a tertiary care cancer centre, each patient is discussed in a multidisciplinary tumour board. The protocols may be tailored to help improve the efficacy of PRRT in any individual patient, and we actually practise personalised medicine.
We may actually combine PRRT with some targeted chemotherapy to improve the efficacy. We may administer some isotopes intra-arterially. We may use tandem therapy whereby two different radioisotopes may be used to give the maximum benefit of PRRT to patients in a particular given setting.
All this is possible because we work with a team of researchers who not just practise the clinical part of PRRT, but are also actively involved in very sophisticated algorithms of dosimetry, of tumour biology, of looking at various cytogenetic and molecular mechanisms which govern the efficacy of PRRT on these patients of neuroendocrine tumours. Our team includes people from the medical oncology field, from pathology, from cytogenetics, from surgical oncology. So many times patients may benefit from a combination of therapy, and that is the benefit which we give to every patient.
PRRT does not just improve the survival of patients, it improves the quality of their life. Many patients of neuroendocrine tumour are miserable because they have intractable diarrhoea, they have flushing, palpitation, hypoglycaemia, and PRRT not just extends the survival of these patients but also improves the quality of their life.
We cater to patients not just from India but also from the surrounding countries, as well as from faraway countries like the United States, Canada, New Zealand, Australia and many of the Southeast Asian countries. Patients come to us not just because of our expertise in treating patients with PRRT, but also because they become our friends for life.
Neuroendocrine tumours are tumours which are relatively indolent, and patients survive for many years with PRRT. And as they get on with their lives, they remain in touch with us and often become our friends for life. So if you need any information about PRRT, please get in touch with our team and we would be happy to share the details of the work that we do and to see whether we can help you with any form of PRRT.