When You First Hear the Words "You May Qualify"
Your oncologist has mentioned radioligand therapy. A friend with prostate cancer had Lu-177 PSMA. Or you've been reading about it yourself after standard therapies stopped working.
You're now asking a straightforward question: what does the doctor need to see before saying yes?
The answer is a set of blood tests and imaging scans. This guide covers what each test does and why your care team needs it.
What Is Lu-177 PSMA Therapy and Why Does Screening Come First?
Lu-177 PSMA therapy (approved as Pluvicto by the FDA in 2022) is a form of targeted radiation therapy for metastatic castration-resistant prostate cancer (mCRPC). It uses a molecule that seeks out a protein called PSMA (prostate-specific membrane antigen), which is commonly found on the surface of prostate cancer cells. Once the molecule attaches, it delivers a precise dose of radiation to those cells.
This therapy only works for patients whose cancer has a specific protein target. Your cancer must express PSMA at a high enough level for the treatment to reach it. Your kidneys and bone marrow must be strong enough to handle the radiation from each cycle. Pre-therapy screening answers both questions.
For a broader overview of eligibility in practice, read: Am I a Candidate for Lu-177 PSMA Therapy? A Plain-Language Guide to Eligibility for Men with Metastatic Castration-Resistant Prostate Cancer.
Who This Screening Process Is Designed For
This evaluation is for men with metastatic castration-resistant prostate cancer, meaning the cancer has spread beyond the prostate and is growing despite hormone therapy (androgen deprivation therapy).
In most countries, to qualify for Lu-177 PSMA therapy, you must have received:
- At least one androgen receptor pathway inhibitor such as enzalutamide or abiraterone
- At least one taxane-based chemotherapy such as docetaxel or cabazitaxel
Guidelines are changing. Some countries now allow earlier treatment. Your oncologist can confirm your path based on your full treatment history.
The Two Gates Every Patient Must Pass
Your care team needs to answer two core questions:
- Does your cancer express PSMA at a high enough level for the therapy to work? This is answered by a PSMA PET scan.
- Is your body strong enough to tolerate the treatment safely? This is answered by blood tests and a general health assessment.
You must pass both gates. If you pass only one, your team will discuss alternatives or revisit eligibility later when circumstances change.
Gate One: The PSMA PET Scan
The PSMA PET scan is the most important test in the eligibility process. It shows how strongly your cancer cells express the PSMA protein throughout your body.
Before the scan, a small amount of radioactive tracer is injected into a vein. The tracer (usually Ga-68 PSMA-11 or F-18 PSMA) travels through the bloodstream and binds to PSMA on cancer cells. A PET camera captures where the tracer binds as bright spots on the images.
What qualifies you on imaging: To qualify, you need at least one tumor site with tracer uptake brighter than the liver. Doctors use the liver as a reference. Brighter spots count as PSMA-positive.
What may disqualify you on imaging: If any measurable tumor site (like a lymph node over 2.5 cm or a lesion over 1 cm) shows low or no tracer uptake, you may not qualify. Parts of your cancer may resist this treatment because they lack the PSMA target that the therapy attacks.
If your PSMA PET scan result is faint or negative, that doesn't mean all options are closed. To understand what those results mean and what your next steps might be, read: Your PSMA PET Scan Came Back Negative or Very Faint — What to Do When Lu-177 PSMA Is Not an Option.
And if you want help understanding what your PSMA PET scan report actually says, our imaging guide walks through the key terms and what each one means for your eligibility: How to Read Your PSMA PET Scan: A Patient Guide to Understanding Your Imaging and Your Lu-177 Eligibility.
Gate Two: The Blood Tests Your Doctor Will Order
Blood tests confirm that your kidneys, bone marrow, and liver can handle treatment. Lu-177 PSMA therapy is highly targeted, but your kidneys and bone marrow still receive some radiation exposure during each cycle. Your baseline blood work helps your team predict how well your organs will handle treatment and sets a reference point to spot any problems later.
Complete Blood Count (CBC)
This test counts your red blood cells, white blood cells, and platelets. It reflects the health and reserve capacity of your bone marrow. The thresholds used in major clinical trials include:
- Hemoglobin (Hb): at least 9.0 g/dL
- White blood cell count (WBC): at least 2,500 per microliter
- Absolute neutrophil count (ANC): at least 1,500 per microliter
- Platelet count: at least 100,000 per microliter
Low results suggest your bone marrow is already stressed from prior chemo, bone metastases, or other causes. Your team may want to address that first or monitor more closely before starting treatment.
Kidney Function Tests
Your kidneys clear the radioactive tracer from your body after each infusion. This means they receive some radiation exposure with every treatment cycle. Poor baseline kidney function increases the risk of further kidney damage over the course of therapy.
Your doctor will typically order:
- Serum creatinine: a waste product your kidneys filter. Elevated levels suggest your kidneys aren't working efficiently.
- Estimated glomerular filtration rate (eGFR): a measure of how well your kidneys filter blood. Most protocols need an eGFR of at least 30 before starting treatment.
Importantly, your team doesn't run these tests just once. The FDA requires kidney function monitoring before and during treatment, not just at the start. This is a formal, built-in part of the treatment protocol.
PSA (Prostate-Specific Antigen)
Your doctor measures your PSA level before starting treatment. It doesn't determine whether you qualify. But it gives your team a personal baseline. PSA changes are tracked to show how the therapy is working over time.
Testosterone Level
Your blood testosterone must stay at castrate levels (below 50 ng/dL) to confirm your cancer is truly castration-resistant despite hormone therapy. Your doctor confirms this with a testosterone test before starting treatment.
Liver Function Tests
These tests measure liver markers (ALT, AST, alkaline phosphatase, bilirubin) and show how well your liver works. Liver metastases and some prior cancer therapies can impair liver function. Abnormal results may affect whether you qualify or how your doctor plans treatment.
Lactate Dehydrogenase (LDH)
LDH is a protein that cells release when they're dying quickly. Elevated LDH can suggest the cancer is highly active. The VISION trial used it to describe patients. High LDH alone doesn't disqualify you, but it helps your team assess your overall situation and likely response.
Additional Imaging Scans You May Need
The PSMA PET scan is the cornerstone of imaging eligibility. Your doctor may also request one or more of the following:
- CT scan of the chest, abdomen, and pelvis: Provides detailed anatomical images of where tumors are located and their size. It complements the PSMA PET scan and helps characterize any lesions that may show low PSMA uptake on the PET.
- Bone scan (technetium-99m bone scintigraphy): An older nuclear medicine scan used to map bone metastases. Still used in some centers alongside or in place of PSMA PET where PSMA imaging is not yet available.
- MRI of the spine or pelvis: May be requested if your care team needs to assess the structural stability of your spine before treatment begins, particularly if you have bone metastases near the spinal cord or vertebrae.
How Doctors Assess Your General Physical Fitness
Beyond blood tests and scans, your oncologist will assess your overall physical condition using a simple scoring system called the ECOG performance status scale. The scale runs from 0 to 4:
- 0: Fully active with no restrictions
- 1: Able to do light work; restricted in physically demanding activity
- 2: Able to care for yourself; not able to carry out work; up and around more than half of waking hours
Most Lu-177 PSMA treatment protocols require an ECOG performance status of 0, 1, or 2. A score of 3 or higher may mean your body is too stressed for treatment, but a radioligand therapy specialist might discuss exceptions.
What the VISION Trial Tells Us About These Thresholds
The blood count minimums and kidney function requirements come from the VISION trial (the Phase 3 study that led to FDA approval). The trial showed that men on Lu-177 PSMA-617 lived a median of 15.3 months versus 11.3 months on standard care, a meaningful gain for men who had already tried multiple prior therapies.
The Prostate Cancer Foundation called this a pivotal shift for advanced prostate cancer, offering a new option when standard therapies fail.
The VISION trial set eligibility thresholds (blood count minimums, kidney function) to protect patients from organ damage while letting the broadest group access treatment. Nuclear medicine teams and oncologists worldwide now use them as the standard.
What Good Results Mean and What They Cannot Promise
Passing all eligibility tests is meaningful. It confirms you qualify for the therapy and your body can likely finish the full course.
But screening can't predict how much you'll benefit. Some patients have significant PSA drops and tumor shrinkage on follow-up scans. Others see more modest changes. Studies show that qualifying patients have the best chance for benefit, but screening just tells you if you can start treatment, not how you'll respond.
Your oncologist will help you weigh the potential gains against the risks given your specific situation, treatment history, and overall health.
Why Your Baseline Test Results Protect You During Treatment
Your baseline tests before the first infusion become your reference point. Your team repeats them before each cycle, usually every six weeks. This ongoing monitoring allows your care team to track changes in your blood counts and kidney function across the full course of treatment.
If your kidneys show early signs of stress or your blood counts fall significantly between cycles, your care team can adjust the timing of your next dose, modify supportive care measures, or pause treatment temporarily to let your body recover. These safeguards work because your baseline tests show which organs need watching.
According to Memorial Sloan Kettering Cancer Center, patients on Pluvicto get blood work before each cycle and organ monitoring throughout treatment, not just at the start.
What International Patients Should Expect When Getting Screened
If you're traveling to India for treatment, complete most screening before you go. This makes your time at the treatment center more efficient and avoids delays when test results are pending after arrival.
Tests you can typically complete in your home country before departing:
- Complete blood count (CBC)
- Comprehensive metabolic panel covering kidney and liver function
- PSA and testosterone levels
- Lactate dehydrogenase (LDH)
- PSMA PET/CT scan (if a nuclear medicine center near you performs this scan)
- CT scan of the chest, abdomen, and pelvis
- Bone scan (if requested by your referring oncologist)
Gather all reports, your treatment history, pathology, and prior scans, and share them with the Indian team before your visit. A patient navigator can help you identify any gaps in your records and ensure everything is in order well before you travel.
The Next Step: Getting Your Reports Reviewed by a Specialist
If you already have a PSMA PET scan and recent blood work, a specialist review of those results is your logical next step. A nuclear medicine doctor or radioligand specialist can check if your numbers qualify and if the full picture supports treatment, and what a realistic plan looks like.
You can submit your PSMA PET scan report, CT results, blood work, histopathology report, and treatment history for a specialist eligibility review. A patient navigator will help you understand what your results mean and guide you through the practical steps toward accessing Lu-177 PSMA therapy.
When to talk to your doctor: If you haven't had a PSMA PET scan yet and your cancer isn't responding to hormone therapy, ask your oncologist about PSMA imaging. If your current team isn't familiar with PSMA PET scanning, ask for a referral to a nuclear medicine specialist or a center with radioligand therapy experience. The PSMA PET scan is the most important first step to understand if Lu-177 therapy is an option, so start this conversation early.
This article is for general information and is not a substitute for medical advice. Always consult your oncologist or care team about your specific situation.
Frequently asked questions
What is the single most important test for determining Lu-177 PSMA eligibility?
The PSMA PET scan is the most important eligibility test. It shows whether your cancer cells express the PSMA protein at a high enough level for the therapy to reach them. Without a positive PSMA PET scan — showing tracer uptake stronger than the liver at measurable tumor sites — Lu-177 PSMA therapy is unlikely to be offered. Blood tests confirm your organs are strong enough to tolerate treatment, but the PSMA PET scan is the first gateway that determines whether treatment can even be considered.
What blood count numbers are required before starting Lu-177 PSMA therapy?
Based on criteria used in the major clinical trials leading to approval of this therapy, you generally need a hemoglobin level of at least 9.0 g/dL, a white blood cell count of at least 2,500 per microliter, an absolute neutrophil count of at least 1,500 per microliter, and a platelet count of at least 100,000 per microliter. These thresholds reflect the minimum bone marrow reserve considered safe for this treatment. Your doctor will check these numbers before each treatment cycle — not just before the first infusion.
How long does the pre-therapy eligibility evaluation typically take?
The timeline depends on where you are and how quickly appointments can be arranged. Blood tests can usually be completed within a few days at any local lab or hospital. Getting a PSMA PET scan may take one to several weeks depending on availability at nuclear medicine centers near you — PSMA PET is not yet universally available in all countries or cities. CT scans are more widely accessible. Most patients complete their full eligibility evaluation within two to four weeks, though this can be shorter in major cities or longer in areas with limited nuclear medicine facilities.
What happens if my kidney function is borderline — does that automatically disqualify me?
Not necessarily. If your estimated glomerular filtration rate (eGFR) is close to the minimum threshold, your care team will weigh the risks and potential benefits carefully in the context of your overall situation. Some centers may proceed with more frequent kidney monitoring or additional protective measures during treatment. However, severely impaired kidney function may be a reason to delay, modify, or reconsider treatment. A specialist experienced in radioligand therapy is best placed to assess what borderline kidney function means for your specific case.
Can I have all my pre-therapy tests done in my home country before traveling to India for treatment?
Yes, in most cases. Blood tests, CT scans, and bone scans can be completed at most hospitals or imaging centers internationally. A PSMA PET scan requires a specialist nuclear medicine center, but these are available in many major cities around the world. Completing as many tests as possible before you travel saves time at the treatment center and allows the specialist team in India to review your records in advance and plan your care more efficiently before you arrive.
Does my prior treatment history affect how my pre-therapy blood tests are interpreted?
Yes, and this is an important point. Prior chemotherapy in particular can reduce bone marrow reserve over time, which may lower your baseline blood counts. Your care team will review your full treatment history alongside your current blood results to understand whether any low values are due to prior treatment effects or to active disease. This context shapes how they interpret your baseline numbers and whether any additional support — such as growth factor injections to boost white cell counts — might be appropriate before treatment begins.