Stereotactic body radiation therapy (SBRT) in the treatment of Neuroendocrine Neoplasms

What is Stereotactic Body Radiation Therapy (SBRT)?

External beam radiotherapy has been around for decades, but the technology has evolved dramatically. Today’s treatments involve new techniques, new machines, and new imaging methods, and these terms are often mixed together in ways that confuse patients. When people talk about “SBRT,” “CyberKnife,” or “Proton Beam,” they are often referring to completely different layers of radiotherapy — a technique, a platform, or a type of radiation. Some names are even brand‑specific. Understanding which layer each term belongs to makes the whole field much easier to navigate. SBRT is an external beam radiotherapy technique, not a machine, not a brand, and not a type of radiation.

You will not find SBRT mentioned in any Neuroendocrine Neoplasms (NENs) guidelines and that’s because it is not yet a “standard of care” for this disease (even though it is mentioned in NCCN guidelines (see below)).

If it is not a standard of care, why did I include SBRT and various techniques in the above summary? I was prompted to include this after noticing two things in my private patient group. Firstly, some patients had received the treatment, and secondly because many people are asking if was “approved” for use in NENs.

This type of therapy is often called Stereotactic radiosurgery (SRS) when used to treat brain tumours. SBRT gives radiotherapy from many different angles around the body. The beams meet at the tumour. This means the tumour receives a high dose of radiation and the tissues around it receive a much lower dose. This lowers the risk of side effects. This type of radiotherapy is mainly used to treat small cancers,

Like conventional surgery, there is a focus on the anatomy so when you look at big sites such as Mayo Clinic, you can see SBRT is used to treat tumours in the lungs, spine, liver, neck, lymph node or other soft tissues. UCLA in California has a great site (click here). They may not specify particular cancer types, only the locations of tumours – so worth remembering this is not a treatment just for NET. That said, there are many clinical trials going on where cancer types are mentioned – keep reading.

On the NIH database, I found 1235 with the term “SBRT” and narrowed that down to 20 with both SBRT and Neuroendocrine Tumours (note: filtering is not an exact science!). Within the space of one month at the beginning of 2023, two studies came up on my radar involving SBRT and NETs. One for functional pancreatic NETs and the other covering Lung NETs. Both are covered below.

Where SBRT Fits in Neuroendocrine Neoplasms (NENs)

SBRT is not listed as a standard of care in any major NEN guideline, including NCCN, ENETS, NANETS, or ESMO. This is because radiotherapy plays a selective, rather than central, role in NET management. However, SBRT is mentioned in the NCCN guidelines in several site‑specific contexts, and there is a growing body of NET‑specific evidence supporting its use in carefully chosen situations.

What the NCCN Guidelines Actually Say About SBRT

Although SBRT is not presented as a universal NET treatment, NCCN does reference stereotactic radiotherapy in multiple tumour‑site sections:

Emerging NET‑Specific Evidence for SBRT

Despite the lack of guideline‑level endorsement, two important evidence streams are shaping clinical practice:

1. SBRT for Functional Pancreatic NETs (Proof‑of‑Concept Study)

A small but influential proof‑of‑concept study demonstrated that SBRT can control hormone‑secreting NETs when surgery is not feasible.

Study: Myrehaug et al., J Radiosurg SBRT (2020). PMID: 32185093.

Key points:

4 patients:
- 3 functional pancreatic NETs (glucagonoma, insulinoma, MEN1‑associated multifocal insulinoma)
- 1 lung NET with ectopic Cushing’s
SBRT reduced hormone secretion and improved symptoms.
Demonstrated feasibility and safety in highly selected cases.

This is not enough to change guidelines, but it is strong enough to influence real‑world practice in specialist centres.

2. SBRT for Early‑Stage Lung NETs (Largest Multi‑Institutional Series)

A multi‑institutional study (Oliver et al., IJROBP) showed that SBRT provides excellent local control for early‑stage lung NETs when surgery is not possible.

ASCO summary conclusion:

“While surgery provides excellent outcomes, SBRT should be considered another treatment option for this patient population.”

This is the strongest evidence to date supporting SBRT as a definitive local therapy for early‑stage lung NETs.

Why SBRT Appears in NET Discussions Despite Limited Guideline Status

Patients are receiving SBRT in real‑world NET practice.
Specialist centres (Mayo, UCLA, Moffitt, MD Anderson) use SBRT for selected NETs based on tumour location, not tumour type.
MRI‑guided SBRT (PRIME‑style adaptive workflows) is increasingly used for pancreatic NETs near sensitive organs.
Clinical trials are emerging, especially in lung and pancreatic NETs.

SBRT is therefore best understood as a selective, anatomy‑driven option rather than a disease‑driven standard of care.

Disclaimer

I am not a doctor or any form of medical professional, practitioner or counsellor. None of the information on my website, or linked to my website(s), or conveyed by me on any social media or presentation, should be interpreted as medical advice given or advised by me.

Neither should any post or comment made by a follower or member of my private group be assumed to be medical advice, even if that person is a healthcare professional. Some content may be generated by AI which can sometimes be misinterpreted. Please check any references attached.

Please also note that mention of a clinical service, trial/study or therapy does not constitute an endorsement of that service, trial/study or therapy by Ronny Allan, the information is provided for education and awareness purposes and/or related to Ronny Allan’s own patient experience. This element of the disclaimer includes any complementary medicine, non-prescription over the counter drugs and supplements such as vitamins and minerals.

General Clinical Trials Disclaimer

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided in the clinical trials document. It’s very important to check the trial inclusion and exclusion criteria before making any contact. If you need questions, the articles here is very useful Questions to Ask About Clinical Trials | Cancer.Net

The inclusion of any trial within this blog should not be taken as a recommendation by Ronny Allan.

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