Why the Salivary Glands Are at Risk During Lu-177 PSMA Therapy
Lu-177 PSMA therapy works by targeting a protein called prostate-specific membrane antigen, or PSMA. This protein appears in large amounts on prostate cancer cells. PSMA is also naturally present in a few healthy tissues, including the salivary glands.
Because the treatment uses PSMA as a homing signal to find and deliver radiation to cancer cells, some of the radioactive compound can also collect in normal salivary tissue. When radiation builds up there, it can affect the glands that make saliva. The result is often dry mouth, which doctors call xerostomia.
The U.S. National Library of Medicine (PMC) has published research on how Lu-177 PSMA-617 accumulates in salivary tissue. The parotid glands sit near your ears and jaw and tend to receive the highest radiation dose of any normal organ during this treatment. The submandibular glands under your jaw are also affected. Together, these glands produce most of your daily saliva.
How Common Is Dry Mouth With Lu-177 PSMA Therapy?
Dry mouth from Lu-177 PSMA is usually mild to moderate. Doctors grade side effects on a scale from 1 to 5. Grade 1 means a slight change you notice but that does not interfere with eating or talking. Grade 2 means more noticeable dryness that may affect what foods you eat or how much you drink. Grades 3 and above are much less common with this treatment.
In the VISION phase 3 clinical trial that led to approval of Lu-177 PSMA-617, dry mouth was among the most commonly reported side effects. According to the National Cancer Institute, dry mouth affected more than 20% of patients who received this therapy.
A more detailed analysis in PMC (U.S. National Library of Medicine) found that grade 1 or 2 dry mouth occurred in approximately 39% of VISION trial participants. The analysis also showed that when adjusted for how long patients were followed, any-grade dry mouth affected about 75 per 100 patient-years, showing how common this side effect is over a full course of treatment.
In the Australian TheraP trial published in PMC, dry mouth of any grade was reported in approximately 60% of participants. Most of these cases were Grade 1, considered mild.
Will the Dryness Go Away After Treatment Ends?
This is one of the most important questions men ask before starting Lu-177 PSMA therapy. For many people, yes. But not always, and the timeline varies from person to person.
Research shows that dry mouth from Lu-177 PSMA tends to be temporary. Studies in PMC found that symptoms improved in many patients in the weeks or months after treatment cycles ended.
However, some men do experience lasting changes in saliva production. This appears more likely with more treatment cycles or if you have had prior radiation to your head or neck. Tell your care team about any history of head or neck radiation before you start Lu-177 PSMA therapy, since that history may affect how your glands respond.
Why salivary gland effects vary between patients is not fully clear. The total radiation dose the glands absorb, the number of treatment sessions, and individual differences all appear to play a role. Because of this, doctors limit the dose to protect your salivary glands during treatment planning.
What This Means If You Have Bone Metastases
If you have bone metastases from prostate cancer, Lu-177 PSMA therapy is often considered because it is a systemic treatment. This means it travels through the bloodstream to reach cancer wherever it is in your body, including in bones and lymph nodes.
This is both a strength and a trade-off. Because the therapy can reach cancer spread throughout your skeleton, it may address disease that localized treatments cannot. But because it is systemic, it also reaches healthy tissues that express PSMA, including the salivary glands.
Men with bone metastases often have advanced disease and may have received several prior treatments. Some may have had prior pelvic radiation. Your oncologist will weigh the potential benefits of Lu-177 PSMA therapy against its possible side effects, including those affecting salivary glands.
If bone pain is part of what you are managing, it may help to review what the evidence shows about Lu-177 PSMA therapy and pain relief from bone metastases, including how this systemic treatment may affect skeletal disease.
What Your Care Team May Do to Protect Your Salivary Glands
Researchers and clinicians are exploring ways to reduce salivary gland exposure during Lu-177 PSMA therapy. None of these approaches is a guaranteed solution, and practices vary between treatment centers. Several strategies are being studied and used in clinical practice.
- External cooling: Applying cold packs or ice to the salivary glands before and during infusion may reduce local blood flow and limit uptake of the radioactive compound in those glands. Some centers use this approach routinely. Early research suggests cooling may reduce gland uptake, and doctors continue to evaluate its role during therapy sessions.
- Eating before infusion: Stimulating saliva flow by eating before treatment may help the glands clear the radioactive compound faster. Your care team may offer specific guidance about eating habits on treatment days.
- Botulinum toxin injections: Some research has tested injecting botulinum toxin into the parotid and submandibular glands prior to treatment, available in PMC. This temporarily reduces saliva output, which may lower gland uptake of the radioactive compound. This approach is still being studied and is not widely available at all centers.
- Careful dose planning: Your care team will balance the dose needed to fight cancer against the dose your glands and kidneys will receive. Limiting cumulative exposure is a standard part of Lu-177 PSMA treatment planning.
- Hydration protocols: Drinking plenty of water before and after infusion helps your kidneys clear the compound faster, which may reduce how long your glands are exposed.
For a broader view of how doctors prepare for and manage all the side effects of this treatment, the article on real-world side effects and management of Lu-177 PSMA therapy for metastatic prostate cancer covers the full safety picture, including effects on blood counts and kidneys.
Managing Dry Mouth at Home
Even when dry mouth is mild, it can affect comfort, eating, and sleep. Here are some practical steps that many patients find helpful. Always check with your care team before making changes, especially if you are managing other treatment effects at the same time.
- Sip water frequently throughout the day. Small, regular sips work better than drinking large amounts at once.
- Avoid caffeine, alcohol, and tobacco, which can make dry mouth worse.
- Eat soft, moist foods. Dry, crunchy, or very salty foods can feel more uncomfortable when saliva is reduced.
- Consider a humidifier in your bedroom at night to reduce nighttime dryness.
- Ask your care team about over-the-counter saliva substitutes or mouth rinses for dry mouth. They may help reduce discomfort, though they won't replace natural saliva.
- Keep up with dental hygiene. Reduced saliva increases the risk of cavities and gum infections. Tell your dentist you are receiving radioligand therapy.
- Chewing sugar-free gum or sucking on sugar-free hard candy may help stimulate your remaining saliva production.
If you have a partner or caregiver helping you through treatment, they can play an important role in helping you stay hydrated, tracking your eating, and noticing any changes that need to be reported to your team. The partner guide for supporting men through Lu-177 PSMA treatment covers practical ways caregivers can help between and during treatment cycles.
Your Dental Health During Lu-177 PSMA Therapy
Dental health is often overlooked before cancer treatment. But it matters a great deal with Lu-177 PSMA therapy, because reduced saliva raises the risk of tooth decay and gum infections.
Before starting treatment, ask your oncologist whether a dental check-up is recommended. Some centers advise a full dental cleaning and exam before the first cycle. If you have cavities or gum disease, treating them first may help prevent problems during therapy.
During treatment, use fluoride toothpaste and ask your dentist if you need a stronger fluoride product. This isn't for everyone, but ask if you have serious dryness.
How Lu-177 PSMA Salivary Effects Compare to Other Radiation Treatments
If you have had pelvic radiation for prostate cancer, you may wonder how Lu-177 PSMA's effects on salivary glands compare to other forms of radiation. They are quite different in character and severity.
External beam radiation to the head and neck can cause severe or permanent salivary damage because the glands sit directly in the radiation field and receive a high, concentrated dose. Lu-177 PSMA delivers a much lower dose to salivary tissue, spread across the entire course rather than focused on one area.
Research shows that salivary gland effects from Lu-177 PSMA are typically milder than those from external beam radiation to the head and neck. This is important to know. Lu-177 PSMA does carry some risk to salivary glands, but it is typically much milder than direct radiation to the head and neck.
Questions to Ask Your Care Team Before Starting
No two men respond exactly the same way to Lu-177 PSMA therapy. Your risk of salivary side effects depends on your treatment history, the number of cycles planned, and your overall health. Talking with your care team before you start is very helpful.
Some questions worth bringing to your oncologist or nuclear medicine physician:
- Based on my case, how likely is dry mouth to be a significant problem during my treatment?
- Does your center use cooling or any other strategies to reduce salivary gland exposure?
- Will you monitor my salivary gland function during and after treatment?
- If dry mouth becomes significant, what would you recommend for relief?
- Should I see a dentist before my first treatment cycle?
When to Talk to Your Doctor
Tell your care team right away if you notice a significant drop in saliva, if dry mouth is affecting your ability to eat or sleep, or if you develop mouth sores or signs of oral infection. Also report any new taste changes, difficulty swallowing, or problems with speech. These may mean your glands need more attention or support.
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
Is dry mouth from Lu-177 PSMA permanent?
For most men, dry mouth tends to improve after treatment cycles end. Published research suggests it is reversible in many cases. However, some men do experience lasting changes in saliva production, particularly after a higher number of cycles or if they have had prior radiation to the head or neck. Ask your care team what to expect based on your specific treatment plan and history.
Which salivary glands are most affected by Lu-177 PSMA therapy?
The parotid glands, which sit near your ears and jaw, tend to absorb the highest radiation dose of any normal organ during Lu-177 PSMA therapy. The submandibular glands, located beneath the jaw, are also affected. Together these are the largest salivary glands and are responsible for most of your daily saliva production.
Can I do anything to reduce my risk of dry mouth before I start treatment?
Some centers use cooling strategies — such as applying cold packs to the glands before and during infusion — or ask patients to eat beforehand to stimulate saliva flow. Good hydration before and after each cycle also matters. Talk to your nuclear medicine team about what precautions they routinely use. It is also worth asking whether a dental check-up before your first cycle is recommended.
How does Lu-177 PSMA salivary gland damage compare to head-and-neck radiation?
They are quite different. Traditional external beam radiation directed at the head and neck delivers concentrated radiation directly to salivary tissue and can cause severe, often permanent damage. Lu-177 PSMA delivers a much lower dose to the salivary glands as a systemic side effect, and published research suggests the overall clinical impact is generally milder by comparison. This does not mean the risk is zero, but the character and severity differ significantly.
Should I tell my dentist I am receiving Lu-177 PSMA therapy?
Yes. Reduced saliva raises the risk of tooth decay and gum infections. Telling your dentist before treatment begins allows them to assess your current dental health, recommend protective measures such as fluoride treatments if appropriate, and monitor for any changes during and after your treatment course.
Will dry mouth affect my quality of life during treatment?
It may. Dry mouth can affect how you eat, sleep, and speak, and even mild dryness can be uncomfortable over time. Sipping water regularly, eating moist foods, using over-the-counter saliva substitutes, and staying consistent with dental care are all practical ways to manage symptoms. Let your care team know how you are feeling so they can offer additional support if needed.