What is Lu PSMA (Lutetium-Prostate Specific Membrane Antigen) Therapy?

Lu177 PSMA Therapy is a treatment for patients with prostate cancer, especially those who have become refractory to conventional therapy. Lutetium PSMA therapy helps to slow down the growth of the cancer cells, reduce the size of the tumours and most importantly improve the quality of life of the patients by reducing the pain caused by the cancer.

Many prostate cancers, in particular those that have spread or become resistant to hormonal therapies, express a unique receptor on their cell surface called Prostate Specific Membrane Antigen (PSMA). When Prostate Cancer metastasizes i.e. spreads to other parts of the body, the PSMA receptor is expressed over the sites of metastases as well.

How does Lu PSMA Therapy Work?

Lutetium-177 is a radioactive substance that emits beta radiation, a destructive kind of radiation. Lutetium-177 is bound to a small peptide which attaches to the PSMA receptor expressed on the cancer cell surface. The Lutetium 177 – PSMA complex, thus attached to the prostate cancer cell, then emits killing radiation causing cell death of the cancer cell. Since the penetration of the emitted beta particle is very small, the surrounding normal cells are spared.

How is the Therapy Done?

Lu177 PSMA is administered intravenously. The patient is admitted to the hospital for 24 hours. A kidney function scan called a MAG3/EC scan is done prior to the administration of the Lu177 PSMA.

What are the Side Effects of Lu PSMA Therapy?

Lu177 PSMA is well tolerated. The most common side effects are a slightly dry mouth, fatigue and nausea. There may also be a slight fall in the white blood cells and platelets about 2 – 3 weeks after the Lu177 PSMA administration.

What is the Response Rate With Lu PSMA Therapy?

The response rates of Lu177 PSMA depend on the tumour biology of prostate cancer, the initial Gleason Score, the extent of disease and the responses to prior therapies. Typically, more than 70% of patients demonstrate a reduction in S. PSA and a shrinkage of tumours following Lu177 PSMA therapy.

When would the doctor consider using this Therapy?

Lu PSMA Therapy is a very specific therapy and is used for managing metastatic Prostate Cancer or when Prostate Cancer is no longer responsive to other types of treatment.

What are the Treatment Schedules with Lu PSMA Therapy?

Most patients undergo three-four treatment cycles at intervals of 8-12 weeks. The number of cycles and the interim duration may vary between individuals depending on the response and interim assessments.

Why should I choose the nuclear medicine therapy center at Fortis Memorial & Research Institute (FMRI), Gurugram (Haryana, India)?

The Nuclear Medicine Therapy Centre at FMRI was one of the first institutes to offer Radio-ligand Therapy with Lu PSMA, and today, the center receives patients from the country and from across the world.

Use of Yttrium 90 (Y-90) and its Side-Effects

Summary (10 sec read)

Yttrium-90 (Y-90) is extensively utilized in nuclear medicine and radiation oncology for targeted radiation treatments. It is predominantly used in radioembolization, a type of internal radiation therapy. This involves inserting Y-90-labeled glass or resin spheres directly into the liver tumor's blood supply through a minimally invasive procedure. These spheres become embedded in the tumor, emit radiation, and eliminate cancer cells while obstructing the tumor's blood flow.

Y-90 is frequently employed for treating liver tumors, primary hepatocellular carcinoma (HCC), and colorectal cancer that has spread to the liver. Additionally, it is used for neuroendocrine tumors (NETs) by attaching it to somatostatin receptor analogs like Dotatoc or Dotatate, a process known as Y-90 PRRT. In certain cases, doctors use Y-90 PRRT alone or in combination with Lutetium Therapy in an alternating protocol called Tandem Therapy, effective for patients with extensive disease.

There are concerns about potential liver damage from Y-90. However, due to its short tissue path length and targeted radiation, surrounding liver tissues remain unaffected. The primary concern is Y-90's nephrotoxicity, which can potentially harm renal function. Hence, Y-90 is used with strict renal protection protocols. With proper precautions, Y-90 can significantly improve outcomes for patients with specific liver conditions.

Yttrium-90 or Y-90 is a commonly used isotope in the medical field specially in departments like nuclear medicine and radiation oncology for radiation therapy. This radioisotope is relied upon to provide a prescribed amount of radiation to a targeted area , such as a tumor. One of the most common uses of Y90 is during an internal radiation therapy called radioembolization.

Radioembolization or Transarterial Radioembolization using Y-90 involves the use of glass/ resin spheres that are filled with the isotope and placed directly into the blood supply of the liver tumor through a minimally invasive procedure. These spheres get lodged within the tumor itself. The doctors then block off the blood vessels to prevent blood flow (embolization). These Y-90 labelled spheres then get to work by radiating and destroying the tumor.

Commonly, Y-90 labelled spheres are used for the treatment of liver tumors, primary hepatocellular carcinoma (HCC) and unresectable primary colorectal cancer that has metastasized to the liver. And sometimes in the treatment of Neuroendocrine Tumors (NETs) by labelling them with somatostatin receptor analog like Dotatoc or Dotatate. This is known as Y-90 PRRT.

In some cases, doctors uses Y-90 PRRT by itself or use it along with Lutetium Therapy in an alternating kind of protocol, so that the patient receives one dose of Lutetium PRRT that’s followed by a dose of Y90, followed by Lutetium and then followed by Y-90 again. This is, what doctors call, Tandem Therapy and has proven to be effective in patients who have got large volume diseases.

In terms of side-effects, there have been speculations that use of Y-90 actually causes collateral damage to the liver. In fact, this is far from the truth. The tissue path length of Y-90 is very short and although Y-90 is a high energy b emitter, it does not penetrate beyond the tumor and the tissues around the liver are spared. The Y-90 only targets the tumor. However, there is one concern regarding the use of Y90 – Y90 is relatively more nephrotoxic than Lutetium, which means that as compared to Lutetium that causes barely any damage to the renal function, Y-90, being a more potent radioisotope has the potential to cause renal damage. This is why doctors use Y-90 extremely judiciously and whenever it is used, it is used with proper renal protection protocols. Actually, Y-90 is nothing to be scared of. With proper precautions, Y90 is extremely beneficial for patients with specific liver conditions and can make a lot of difference to the disease outcome.