Is Terbium 161 Given in cycles?

Cyclic Dosing of Terbium-161 Therapy: Precision-Guided Cancer Treatment

Terbium-161 (Tb-161) therapy, particularly with [161Tb]Tb-PSMA-I&T, is administered in multiple treatment cycles to maximize therapeutic impact and ensure patient safety in cases of metastatic castration-resistant prostate cancer (mCRPC). The approach reflects a scientifically validated strategy for targeting both visible tumors and micrometastatic disease.

Why Cycles Matter

Tb-161 is typically delivered over up to six cycles, spaced at six-week intervals. This schedule allows for sustained pressure on tumor cells across time, increasing the probability of disrupting their growth and survival. Micrometastases, which are small cancer deposits often resistant to single-dose treatment, benefit from repeated radiation exposure in a way that helps improve long-term outcomes.
Each cycle also offers an opportunity to review how the disease is responding and whether side effects are emerging. This is a critical advantage over single-dose treatments.

The Role of Scientific Dosimetry

After every cycle, patients undergo SPECT/CT scans, which allow clinicians to measure the actual radiation dose absorbed by both tumors and healthy organs. Using voxel-based 3D dosimetry models, the treatment team can make informed decisions about adjusting future doses. This process helps tailor the therapy to the patient’s specific disease profile while minimizing risks to the kidneys, salivary glands, and bone marrow.

Evidence from Research

Clinical evidence from the VIOLET trial confirms that this dosing strategy is both safe and effective. Tb-161 has demonstrated higher tumor dose delivery compared to Lu-177, without significant added toxicity. Supporting research has also emphasized the role of cyclic administration and advanced dosimetry in improving the therapeutic index of radioligand therapies.


https://pmc.ncbi.nlm.nih.gov/articles/PMC10945337



This combination of scheduled cyclic therapy and scientific monitoring makes Tb-161 therapy a precise and adaptable option in advanced prostate cancer care.

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