Terbium-161 Radiotherapy in India

Terbium-161 (Tb-161) radiotherapy is an emerging targeted radioligand therapy that combines beta particles with a dense burst of Auger and conversion electrons to destroy cancer cells at the single-cell level. 

In India, it is offered to selected patients with metastatic castration-resistant prostate cancer (mCRPC) at Theranostics Centre, Sarvodaya Hospital, Faridabad, under Dr. Swagat Dash. It remains investigational: the strongest data come from phase I/II and early real-world studies, not randomised trials.

What is Terbium-161 radiotherapy?

Terbium-161 radiotherapy attaches radioactive Tb-161 to a ligand, such as a PSMA-binding molecule, that homes in on cancer cells. Tb-161 releases beta particles plus short-range Auger and conversion electrons, delivering radiation directly to tumour cells while sparing most surrounding tissue.

• Tb-161 is a radiolanthanide, chemically similar to lutetium, with a half-life of about 6.95 days before it decays to stable dysprosium-161.
• In prostate cancer, the carrier is a PSMA ligand (for example PSMA-I&T or PSMA-617), chosen after a PSMA PET scan confirms the target is present.
• Its gamma photons (49 and 75 keV) allow post-therapy SPECT/CT imaging, so delivered dose to tumours can be estimated.

Put simply, Tb-161 is a theranostic isotope: the same targeting molecule that is imaged is then used to treat.

How does Terbium-161 therapy kill cancer cells?

The PSMA ligand carries Tb-161 to prostate cancer cells, where beta particles damage DNA over a few millimetres and Auger and conversion electrons add intense, very short-range damage inside and around the targeted cell. Unrepaired DNA breaks then trigger cell death.

• Beta cross-fire: beta particles (mean energy 154 keV) reach neighbouring tumour cells, which helps when PSMA expression is uneven across a lesion.
• Short-range electrons: Auger and conversion electrons travel only micrometres; at distances below about 0.1 mm, dose per decay is more than double that of Lu-177.
• Cell-level damage: a simulation study presented at SNMMI suggests these electrons injure the cell membrane, cytoplasm and nucleus, not only the DNA.
• Normal tissue: salivary glands and kidneys also express PSMA, so they are monitored closely during treatment.

This dual range is the rationale for using Tb-161 against both bulky deposits and microscopic disease.

How is Terbium-161 different from Lutetium-177?

Tb-161 matches Lu-177 in half-life and beta energy but emits far more short-range electrons: about 48 keV per decay of conversion and Auger electrons versus about 15 keV for Lu-177, per a 2025 EJNMMI Research analysis. This may improve killing of micrometastases and single tumour cells.

• Monte Carlo simulations suggest Tb-161 delivers a higher dose to the nuclei of single tumour cells and small clusters than Lu-177, as noted in the VIOLET trial report.
• No head-to-head clinical trial has proven Tb-161 superior. The advantage is mechanistic and still being tested.

For established Lu-177 treatment, see our page on Lutetium-177 PSMA therapy.

Who is eligible for Terbium-161 therapy in India?

Tb-161 PSMA therapy is considered for adults with PSMA-positive mCRPC that has progressed after androgen receptor pathway inhibitors and usually taxane chemotherapy or Lu-177 PSMA therapy, with adequate organ function and performance status. Final eligibility is decided case by case by the treating team.

• PSMA-avid disease: VIOLET required high PSMA uptake and no discordant FDG-avid disease; 3 of 33 screened men were excluded for low PSMA uptake or FDG discordance.
• Fitness: the trial enrolled ECOG performance status 0-1; adequate blood counts, kidney function and life expectancy are reviewed.
• Prior treatment: progression on Lu-177 does not automatically exclude you, but Actinium-225 PSMA therapy may be weighed alongside Tb-161. Our comparison of Lutetium and Actinium strategies explains how that choice is made.
• Usually not suitable: PSMA-negative or FDG-discordant disease, severely reduced bone marrow reserve, or poor kidney function that cannot be corrected.

Bring your latest PSA trend, scans and treatment history for an accurate assessment.

How is Terbium-161 therapy delivered at Theranostics Centre?

Tb-161 is given as an intravenous infusion in a day-care setting, usually over 4-6 cycles spaced 6-8 weeks apart, according to the centre’s protocol. Imaging, blood tests and PSA guide every step.

• Work-up: PSMA PET/CT, often FDG PET, blood counts, kidney and liver tests, and review of prior therapy.
• Planning: a multidisciplinary discussion confirms the isotope and number of cycles.
• Infusion: a single outpatient visit per cycle; most patients resume routine activity soon after.
• Imaging after treatment: Tb-161’s 75 keV photon supports quantitative SPECT/CT for dosimetry.
• Follow-up: PSA and repeat imaging assess response; radiation-safety advice is given at discharge.

Each cycle is adjusted to blood counts and response, not to a fixed schedule.

What are the side effects of Terbium-161 therapy?

In VIOLET, treatment-related grade 3-4 events occurred in 7% of patients, with no treatment-related dose reductions, delays or deaths. A pooled analysis found 124 adverse events across studies, of which only 18 were high grade (PubMed).

• Expected effects: fatigue, nausea, dry mouth and temporary drops in blood counts, as seen with PSMA radioligand therapy generally.
• Monitoring: regular blood and kidney tests before each cycle.
• Comparison: current evidence suggests safety is comparable to Lu-177 PSMA therapy.
• Unknowns: long-term toxicity data are limited because follow-up is still short.

Report fever, bleeding or severe fatigue promptly; most effects are manageable with supportive care.

Can Terbium-161 treat cancers other than prostate cancer?

Tb-161 is being investigated beyond prostate cancer, including neuroendocrine tumours (NETs) and FAP-expressing solid tumours, but evidence there is preliminary and limited to first-in-human and early studies.

• NETs: a first-in-human study of Tb-161-DOTATOC showed high-quality SPECT/CT, including small liver metastases. See our note on Tb-161 DOTATATE for resistant NETs and PRRT.
• Solid tumours: the centre has reported Tb-161-FAP-2286 therapy within its FAPI-targeted programme.

Use in these settings is individualised and should follow a specialist consultation.

How much does Terbium-161 therapy cost in India?

The cost depends on the number of cycles, administered activity, targeting ligand, imaging and day-care charges, and is quoted after clinical review rather than as a flat package, because Tb-161 is a newly available isotope.

• Drivers: cycles planned, PSMA and FDG PET scans, laboratory monitoring and post-therapy imaging.
• Estimate: request an itemised written estimate before starting.
• Questions to ask: how many cycles are included, whether PET scans and post-therapy imaging are bundled, and what happens if therapy is stopped early.
• Overseas patients: our international patient desk can coordinate records, virtual review and travel planning.

A transparent estimate after review beats any advertised price that ignores your clinical situation.

Theranostics Centre, Sarvodaya Hospital, for Terbium-161 therapy in Delhi NCR

In June 2025, Sarvodaya Hospital, Faridabad announced that it had become India’s first theranostics and nuclear medicine centre to offer Tb-161 PSMA therapy, led by Dr. Swagat Dash, HOD and Senior Consultant, Nuclear Medicine.

• One pathway: PSMA PET, Lu-177, Ac-225 and Tb-161 options reviewed together.
• Experience: read about Dr. Swagat Dash and our testimonials.
• Access: Sector 8, Faridabad, within reach of Delhi airport.

To discuss your case, book an appointment with the nuclear medicine specialist in India.