A blog by Ronny Allan

Neuroendocrine Cancer: Troublesome Thyroids (Updated 2026 Edition)

Neuroendocrine Cancer: Troublesome Thyroids (Updated 2026 Edition)
Thyroid information disclaimer

This content is for general education and reassurance only. It is not a substitute for personalised medical advice, diagnosis, or treatment. Thyroid nodules, thyroid function tests, cytology categories (Bethesda/THY), and molecular tests (such as ThyroSeq, Afirma, or ThyroidPrint) all require interpretation by qualified clinicians who know your full medical history, imaging, pathology, and symptoms.

Thyroid disease is common and highly individual. Most nodules are benign, and many thyroid abnormalities are incidental findings — especially in people who undergo frequent imaging. Decisions about biopsy, molecular testing, surgery, or surveillance should always be made with your endocrinologist, surgeon, or multidisciplinary team (MDT).

If you have concerns about your thyroid, symptoms, or test results, please speak with your healthcare team. They can provide guidance tailored to your situation, including whether further testing or treatment is appropriate.

 

When my thyroid first joined the party

Back in 2013, just when I thought things were settling, I was told I had a “lesion” on the upper left lobe of my thyroid — and that it had been quietly monitored for a while. If you live with NETs, you’ll know the feeling: your mind immediately jumps to metastasis. I’d already had major surgery, so the idea of another problem was not welcome. 

Additionally, I had an odd disposition of issues above the diaphragm and I could see a trend in this area, particularly on the left.  See Odd Disposition section below.  However, like a lot of things in NET, correlation is often incorrect. 

 

Why thyroid findings are so common in NET patients

Thyroids come up constantly in NET discussions, and for good reason:

  • We get lots of scans, so we discover incidental nodules most people never know about.

  • Somatostatin analogues can nudge thyroid function downward.

  • Autoimmune thyroid disease is extremely common in the general population.

  • SSTR PET scans often “light up” the thyroid, usually for benign reasons.

  • And yes — there is one thyroid cancer with a NET connection (MTC), but it’s rare.

So if your thyroid has ever caused a raised eyebrow on a scan report, you’re in good company.

 

Metastases to the thyroid are very rare

One important point often missed in patient discussions is that the thyroid is almost never a site of metastasis. Despite its rich blood supply, the thyroid is an unusually unfriendly environment for metastatic tumour cells. Large surgical and autopsy series consistently show that 97–99% of thyroid tumours are primary thyroid tumours, not metastases from elsewhere.

When metastases do occur, they most commonly come from kidney, lung, breast or melanoma — and even those are rare. For NET patients, metastasis to the thyroid is exceptionally rare, limited mostly to isolated case reports.

 

Bottom line

Thyroid cancer is much more common than NETs, and 97–99% of thyroid tumours are primary thyroid tumours, not metastases. So when a thyroid nodule appears on a scan, the overwhelming statistical likelihood is that it is a primary thyroid issue — and most of those are benign.

 

My own diagnostic journey

I’ve had several FNAs and one core biopsy. The FNAs were inconclusive; the core showed only fibrous tissue. The final label: THY3F — meaning a follicular‑patterned lesion that could be benign or malignant.

Most THY3F nodules turn out to be benign follicular adenomas, but the category exists because cytology alone can’t distinguish them from follicular carcinoma.

My head and neck surgeon (who also specialises in thyroids) explained that removing half or all of the gland would mean lifelong hormone replacement — potentially for something that might never trouble me. As nothing was palpable and I had no symptoms, we agreed on watch and wait.

Later, mild hypothyroidism appeared on blood tests, so I started low‑dose levothyroxine. My levels have been stable ever since.

 

Where the thyroid sits — and why it matters

The thyroid is a small, butterfly‑shaped gland at the front of your neck. Despite its size, it has a huge job: producing T4 (thyroxine) and T3 (triiodothyronine), hormones that regulate metabolism in every cell of the body.

When something goes wrong with the thyroid, symptoms can overlap with NET symptoms — fatigue, bowel changes, weight changes, temperature intolerance — which is why proper testing matters.

 

Thyroid nodules: extremely common, usually harmless

If you have a thyroid nodule, you are far from alone.

Modern ultrasound studies show:

  • Up to 65% of adults have at least one nodule by age 60

  • >90% are benign

  • Many are cysts, not solid nodules

  • Women are affected more often than men

  • Most nodules never cause symptoms

NET patients simply discover more of them because we’re scanned so often.

Modern evaluation (2024–2026)

Today, nodules are assessed using:

  • TI‑RADS ultrasound scoring

  • FNA biopsy when indicated

  • Molecular testing such as ThyroSeq, Afirma and ThyroidPrint, is available in both the US and Europe and often used for indeterminate cytology such as Bethesda IV (THY3F in the UK). Some countries may still be trialling it. 

Molecular testing has dramatically reduced unnecessary thyroid surgery.

 

Hypothyroidism and hyperthyroidism

Hypothyroidism (underactive thyroid)

Symptoms include fatigue, feeling cold, weight gain, constipation, low mood and brain fog.

Common contributors include:

  • Hashimoto’s thyroiditis (very common in the general population)

  • Somatostatin analogues, which can slightly lower thyroid hormone levels in some people, usually mildly and without symptoms

  • Thyroid surgery

  • Radiation exposure (rare in NETs)

Most people on SSAs do not develop clinically significant hypothyroidism, but if you already have borderline thyroid function or autoimmune thyroid disease, SSAs can make a small difference — which is why routine monitoring is sensible.

Hyperthyroidism (overactive thyroid)

Symptoms include weight loss, heat intolerance, anxiety, palpitations, diarrhoea and gritty or sore eyes (in Graves’ disease).

Hyperthyroidism is less common than hypothyroidism but still far more common than NETs.

 

SSTR PET uptake in the thyroid — what it really means

SSTR PET (Ga‑68 or Cu‑64) frequently shows thyroid uptake. Most of the time, it is:

  • Physiological

  • Thyroiditis

  • Benign nodules

Modern interpretation:

  • Diffuse uptake → usually thyroiditis

  • Focal uptake → needs ultrasound, but still usually benign

  • Very rarely NET metastasis

 

Medullary Thyroid Cancer (MTC): the only meaningful NET connection

MTC arises from C‑cells, not follicular cells. It accounts for ~3% of thyroid cancers, and 25% are familial (MEN2A, MEN2B, FMTC). RET gene testing is essential for families.

Importantly:

  • MTC does not reliably express SSTR2, so it usually does not show up on SSTR PET

  • It is better detected with ultrasound, CT/MRI, FDG PET or F‑DOPA PET

  • Calcitonin and CEA are the key blood markers

For NET patients, the important message is: MTC is the only thyroid cancer with a strong neuroendocrine link — and even then, it behaves differently from classic NETs.

 

Parathyroids — close neighbours, different job

The parathyroids regulate calcium, not metabolism, and are only relevant to NETs in the context of MEN1 or MEN2. They sit next to the thyroid but are a completely separate organ.

 

My latest thyroid update (2024–2026)

My thyroid nodule remains stable on ultrasound and CT. My thyroid function tests are normal on low‑dose levothyroxine. No PET scan since 2021 has mentioned the thyroid. My MDT continues to view this as an incidental, non‑NET‑related finding.

In short — stable, boring, and behaving itself.

 

What NET patients should remember about thyroids

  • Thyroid nodules are extremely common – click here to read more

  • Most are benign

  • SSTR PET uptake is usually not cancer

  • SSA therapy can slightly lower thyroid function

  • MTC is the only thyroid cancer with a NET connection

  • Symptoms of thyroid disease can mimic NET symptoms

  • Blood tests (TSH, T4, T3) are simple and reliable

  • Watch‑and‑wait is often appropriate

 

Short Primer on WHO 2022 Thyroid Tumour Classification — Main Types

The 2022 WHO edition reorganises thyroid tumours by cell of origin and malignant potential, with three major families:

 

1. Follicular‑cell–derived tumours

(These are by far the most common thyroid cancers.)

Benign

  • Follicular adenoma

  • Oncocytic (Hürthle cell) adenoma

  • Thyroid follicular nodular disease (new umbrella term replacing “multinodular goitre”)

Low‑risk neoplasms

  • Non‑invasive follicular thyroid neoplasm with papillary‑like nuclear features (NIFTP)

  • Hyalinizing trabecular tumour

Malignant

  • Papillary thyroid carcinoma (PTC) — with multiple subtypes

  • Follicular thyroid carcinoma (FTC)

  • Oncocytic (Hürthle cell) carcinoma

  • Poorly differentiated thyroid carcinoma (PDTC)

  • Differentiated high‑grade thyroid carcinoma (new category)

  • Anaplastic thyroid carcinoma (ATC)

    • Includes squamous‑cell carcinoma pattern (now considered a subtype of ATC)

2. C‑cell–derived tumours

(Neuroendocrine‑type, but biologically distinct from GEP‑NETs)

  • Medullary thyroid carcinoma (MTC)

    • Sporadic

    • Hereditary (MEN2A, MEN2B, FMTC)

 

3. Other rare thyroid tumour families

Salivary‑gland–type carcinomas of the thyroid (new category)

Examples include:

  • Mucoepidermoid carcinoma

  • Secretory carcinoma

Thyroid tumours of uncertain histogenesis (new category)

  • Cribriform‑morular thyroid carcinoma (now its own type, no longer a PTC subtype)

 

Notes on Thyroid Cancer classification above

  • “Follicular nodular disease” replaces the old benign multinodular goitre terminology.

  • “Oncocytic” replaces “Hürthle cell” throughout.

  • Cribriform‑morular carcinoma is now a distinct tumour type, not a PTC subtype.

  • Differentiated high‑grade thyroid carcinoma is a new malignant category bridging well‑differentiated and poorly differentiated cancers.

  • Grading (mitoses, necrosis, Ki‑67) is now applied to follicular‑cell tumours and MTC.

  • ATC now includes squamous‑cell carcinoma as a morphologic pattern.

 

Overdiagnosis of regular thyroid cancer and overtreatment — is it still a major issue?

Papillary microcarcinomas (<1 cm) are now often managed with active surveillance, not surgery. Many countries have updated guidelines to reduce unnecessary thyroidectomy. Most small thyroid cancers are indolent and never cause harm.  

This is important for NET patients who already live with enough uncertainty.

Final thoughts

Thyroid findings can be unsettling when you already live with NETs, but most are harmless and manageable. As always, context matters — and fear thrives in the absence of information.

If your thyroid ever joins the party, remember: It’s usually a ‘gatecrasher’, not a NET guest.

My “odd disposition” of tumours/lesions

I remember finding out about my thyroid lesion and was convinced there was an ‘above the diaphragm’ trend and it was all related. When I say, “above the diaphragm”, I mean the thoracic cavity, head and neck.  At this point, it’s worth mentioning something from my “above the diaphragm” cancer history which I initially assumed was related but it would appear to be an incidental finding (coincidence).  

Above the diaphragm.  I also had since my  initial diagnosis, evidence of a hotspot in my left supraclavicular fossa (SCF) lymph nodes (near the clavicle), geographically close to the thyroid (and my lesion is left-sided).  5 SCF nodes were removed from this area in Feb 2012 for an exploratory biopsy which subsequently tested negative and CT and Ultrasound both show nothing vascular or pathologically enlarged. BUT …. there is still a hotspot showing on a subsequent Octreoscan and 2x Ga68 PET since the nodes were removed in 2012.  Curiously, the Ga68 PET also lit up the left sub-pectoral lymph node area, I suspect this is another potential physiologic uptake/reactive node.   I also had positively tested nodes removed from my left axillary (armpit) during the same procedure (my distant disease has always been left-sided to date). I also have an incidental lung nodule which they now just monitor.

The surgeon who operated on my left axillary and SCF nodes also specialises in Thyroids and so it was an easy decision to ask to be referred to him. He explained that whilst he could just take the left lobe or the whole thyroid, it would mean lifelong treatment to add to my current burden and perhaps for something which will never trouble me. As nothing is palpable and I have no symptoms, I agreed to a ‘watch and wait’ approach. I had regular tests for a couple of years and once he was happy with stability he referred me back to the NET MDT for monitoring.  He also tracked my thyroid blood panel and I ended up with a low dose thyroxine supplement for mild hypothyroidism (see above).

But as with many things in NETs, the simple explanation wasn’t the right one.

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.


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Ronny

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By Ronny AllanOn 7 Comments
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By Ronny Allan

Ronny Allan is a 3 x award-winning accredited patient leader advocating internationally for Neuroendocrine Cancer and all other cancer patients generally. Check out his Social Media accounts including Facebook, BlueSky, WhatsApp, Instagram and and X.

7 thoughts on “Neuroendocrine Cancer: Troublesome Thyroids (Updated 2026 Edition)”

  • Diana Lewis

    Not only was my NETs undiagnosed for 20 years so we’re the tumors on my thyroid. After years of medication and biopsies showing benign results I had surgery 2 months after mid-gut NETs was accidentally found. The reason for thyroid surgery even though the most recent 2 month old biopsy showed benign was a nodule on my thyroid so large you could see it in a chest x-ray and swallowing was difficult. Turns out it was papillary on one side and follicular tumors on the other lobe. It’s mass had pushed my trachea into a backwards “C”, making it hard to swallow. Unless the needle goes into the affected site, it will show it to be benign, is what I was told. Over the 20 year period I had about 14 biopsies…all normal. No surgeon would touch it. The surgeon who found my NETs also removed my thyroid because he said any mass that large and intrusive to even swallowing water should be removed.

    Reply
    • Deanna

      Ditto for going @ 20years before getting a diagnosis. Good to meet a fellow-traveller.

  • Thall

    Do not wait any see in anything is my opinion!! That was our first mistake when my moms back surgeon wanted to watch and wait in the lesion in her L5 I begged them to biopsy they insisted on doing the back surgery first as she was in a great deal if pain! No biopsy until I asked again and guess what? This is how it was discovered she had neuroendocrine cancer ! Then the search began! It had spread from intestines to the L5 and a few other places! Thyroid same thing saw it light up on scan no one was too concerned about cancer! Several painful biopsy’s later all just as you said not got samples! We decided we wanted it taken out WE did! And it turns out papillary cancer so now going back in the removed the rest of thyroid! I saw bee aggressive! Never wait and watch NEVER!!!

    Reply

    • I understand what you are saying but every patient’s experience is different. I’m well aware of the situation with my diagnosis and ongoing surveillance and have an excellent team. Many patients are on watch and wait for many tumors and in fact it is documented in all the NET specialist guidelines that this is often the best option. Thanks for your concern and I hope your mom is doing OK?

  • This was of interest to me too, since I was diagnosed with a completely unrelated cancer in a saliva gland seven months after my NETS diagnosis. It was removed surgically, followed by radiation. I had CT scans of head, neck, chest, abdomen & pelvis last week and I’m waiting for the results.

    Reply

  • Well done, Ronny. Both my mother and one of my sisters had thyroid cancer and did well after the thyroid was removed.

    We NETs patients do well to always think a new lesion is a NET metastasis but sometimes it is not. When I was treated for urinary bladder cancer, I had to fight the urinary surgeon hard to make sure the biopsy checked to make sure it was not neuroendocrine cancer. It was not NETs and he said “I told you so, it is too rare.” I was glad that I demanded the biopsy anyway. They don’t seem to recognize that it is not as rare if the patient is already known to have NETs.

    Have the best possible outcomes,
    Cy

    Reply

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