Neuroendocrine Cancer is one of a number of “difficult to diagnose” conditions. Many types of Neuroendocrine Cancer come with an associated syndrome and these syndromes can mimic everyday illnesses. In some cases, many people don’t feel ill while the tumours grow. Most types of this cancer are slow-growing but there are also aggressive versions. Although things appear to be improving in diagnostic terms, it can sometimes take years for someone to be finally diagnosed correctly and get treatment, albeit in some cases, too late for any hope of a curative scenario. It’s a very sneaky type of cancer and if left too long it can be life threatening – CLICK HERE to find out why.
The road to a diagnosis of Neuroendocrine Cancer is often not straight or easy to navigate. It’s not only a sneaky type of cancer but it’s also very complex. It’s a heterogeneous group of malignancies with a varied and confusing histology and nomenclature to match. As I said above, many people are asymptomatic for years whilst the tumor grows and some might say that it’s somewhat ‘lucky’ to have symptoms to help aid a diagnosis. Many find that a lack of knowledge of Neuroendocrine Cancer in primary care, doesn’t always produce results. Common misdiagnoses include (but not limited to), Irritable Bowel Syndrome (IBS) and other common digestive diseases, menopause, appendicitis, hypertension, gastritis, asthma. Neuroendocrine Cancer is much more likely to be diagnosed at secondary care if a referral for ‘something’ can be achieved.
……..cue internet searches (Dr Google)
I think the rise and the power of the internet and rise of social media applications is very much helping generate awareness and knowledge of Neuroendocrine Cancer and those looking for a diagnosis may find help in this way. I suspect this instant access to information has played its part in the diagnostic improvements I mentioned above. Take my own efforts for example, I’m a wee Scottish guy with a computer and I’m already accelerating towards a million blog views – there’s clearly a market for what I produce. In terms of those looking for a diagnosis, if only one gets an earlier diagnosis due to my site, I’ll be happy.
Unfortunately, the internet can often be a minefield and in many cases, can lead to quite unnecessary worry for those looking for a solution.
I’m contacted almost daily by the ‘undiagnosed’ who suspect they have Neuroendocrine Cancer, often because they appear to be displaying the symptoms of one of the associated syndromes. These are some of my most difficult questions. I’m always very wary of initially agreeing with their assumptions and logic, instead opting for straightforward detective work based on my knowledge of the different types of Neuroendocrine Cancer, knowledge of the best scans, tumour markers, hormone markers. And I always warn them that statistically, they are more likely to have a common condition than the less common Neuroendocrine Cancer.
Many have already had multiple doctor’s appointments and tests. If they have not yet had a scan, I encourage them to try to get one ‘by hook or by crook’. Despite what you read on patient forums and surveys, the vast majority of Neuroendocrine diagnoses will be triggered by a conventional imaging such as CT and/or MRI. If you can see it, you can detect it.
When I first chat with the ‘undiagnosed’, I find many of them are fairly knowledgeable about Neuroendocrine Cancer and other health conditions, again confirming the power of the internet and the savvy ‘internet patient’. This is fine if you look in the right places of course – for certain things there are more wrong places on the internet than right ones.
If I have time, I’m happy to chat with these people, some are very frustrated – in fact some are so frustrated that they just want a diagnosis of something even if that something is really bad. Some are not showing anything on any scan but in certain cases, it can be likened to finding a needle in a haystack.
What do you say to someone who is utterly convinced they have Neuroendocrine Cancer but CT/MRI/Octreoscan/Ga68 PET are all clear, Chromogranin A and 5HIAA are in range but they still say they have (say) diarrhea with its potential for literally thousands of differential diagnoses. It’s a tough gig.
My scan came back normal. That should be good news. But, if there is no tumor, how can I be suffering from all the symptoms of carcinoid syndrome? Is that diagnosis wrong? Are the urine and blood test results wrong? I’m awaiting a MRI scan to take another look to see if the doctor can find anything. I don’t know what they’ll find. I don’t want them to find anything. But I’m afraid of what will happen if they don’t.
I always let the undiagnosed know that Neuroendocrine Cancer patients are some of the most friendliest and helpful people you can meet, they will treat you as one of their own. There will be a number of diagnosed people online who have gone through what the undiagnosed are going through, so they will both sympathise and emphasise. But … this can often have the adverse effect of pushing them into believing they must have Neuroendocrine Cancer. This makes for interesting discussions given the number of people who automatically assume that ‘flushing’ or ‘diarrhea’ (as described by the undiagnosed) must be Neuroendocrine Cancer without any reference to the many differential diagnoses and the context of what that actually means in Neuroendocrine Cancer terms.
10 Questions to ask your doctor/specialist for those Diagnosed with Neuroendocrine Cancer (and where to find a specialist)
I once wrote an article for DIAGNOSED NET Patients suggesting 10 Questions to ask their doctor. So I wanted to take a step back in context, using the knowledge I now have, and put myself in the shoes of someone who thinks they may have Neuroendocrine Cancer but is not yet diagnosed.
Key questions to ask your doctor/specialist for those trying to confirm or discount Neuroendocrine Cancer
Dear undiagnosed people. I totally understand your fear. There’s nothing worse than being ill and not knowing what illness you have. I’ve therefore compiled a list of 3 key questions for you to ask – think of it as a tick list of things to ask your doctor to do or check . I have linked several background articles for you to prepare your case. However, I cannot promise your doctor will agree or take any action, in fact some might be annoyed about the lack of trust. However, doing your homework really helps, including diaries and other evidence.
I also wouldn’t say that a negative to all the questions will mean you definitely do not have Neuroendocrine Cancer but at least these questions might provide your doctor and yourself with some food for thought, perhaps leading to the diagnosis of ‘something’. The questions below assume that routine blood tests have been done, including Full Blood Count, Liver, Renal, Bone, Glucose.
Questions for the UNDIAGNOSED to ask their treating physician
“I think I might have a type of cancer known as Neuroendocrine Cancer or Neuroendocrine Tumours (NET) because <<< insert your own story>>>. Would you please consider the following tests and checks:”
1. Chromogranin A (CgA) is a marker which is quite sensitive for Neuroendocrine Tumours, essentially measuring tumour bulk potentially indicating the presence of Neuroendocrine Tumours. There can be other reasons for an elevated CgA figure, including the patient’s use of proton pump inhibitors (PPI) (see the article for an alterative test where this is the case). Read more here – Neuroendocrine Cancer – Tumour and Hormone Marker tests.
3. Scans. Most NETs can be seen on a CT scan although liver metastasis can often show more clearly on an MRI. There are also nuclear scan options to confirm conventional imaging findings. Some NETs may be accessible via endoscopy and ultrasounds can also give hints for further investigation. In some cases, nuclear scans will find things that conventional imaging cannot because radionuclides can normally pick up oversecreting tumours. Read more in my article “If you can see it, you can detect it”.
You can hear two NET specialists talking about the issues surrounding the diagnostics here.
Scanning is a key diagnostic support and surveillance tool for any cancer. Even though you have elevated bloods or urine (….or not), a picture of your insides is really like a thousand words…. and each picture has a story behind it. Scanning can be a game changer in the hunt for tumours and although scans do not normally confirm the cancer type and grade, they certainly help with that piece of detective work and are key in the staging of the cancer.
When I read stories of people in a difficult diagnosis, I always find myself saying ‘a scan might resolve this’ and I always suggest people should try to get one. Even in the case of a story about late diagnosis or a misdiagnosis, I find myself thinking ‘if only they had done a scan earlier’. Despite what you read on NET forums, a CT scan will be able to find some evidence of tumour activity in 90-95% of cases. However, some are cunningly small or hiding and it can be like trying to find a needle in a haystack.
However, scans are not an exact science…..not yet! Apart from human error, sometimes tumours are too small to see and/or there are issues with ‘pickup’ (i.e. with NETs, nuclear scans need efficient somatostatin receptors). The differences between scan types are more quality (sensitivity) related as new technologies are introduced.
As for my own experience, I was very lucky. I managed to get a referral to a specialist early on in my diagnosis phase. He looked at the referral notes and said “what are you doing this afternoon“. I replied “whatever you want me to do“. He didn’t know I had cancer but his instincts led him to believe he needed to see inside my body, he wanted to scan me. The scan results were pretty clear – I had a metastatic Cancer and further checks were now needed to ascertain exactly what it was. So I took my seat on the roller coaster. Medicine is not an exact science (not yet anyway) but here’s something I believe is a very common occurrence in all cancers – If your doctors don’t suspect something, they won’t detect anything.
There’s frequent discussion about the best types of scans for different types of NETs and which is best for different parts of the anatomy. There’s also different views on the subject (including in the medical community), However, a few well known facts can be gleaned from authoritative NET sources:
Computed Topography (CT)
CT scans are often the initial imaging study for a patient presenting with signs or symptoms suggestive of many cancers including NET. These studies are most useful for disease staging and surgical planning as they provide excellent anatomic detail of the tumors themselves and surrounding structures. Primary NETs (GI and lung NETs) and their metastases are generally hyperenhancing with IV contrast and are best seen in the arterial phase of a triple phase CT scan.
In primary NETs, the average sensitivity of a CT scan is 73%. CT scans have even better sensitivity in detecting NET metastases, as they demonstrate 80% sensitivity for liver metastases (but see MRI below) and 75% sensitivity for other metastases (non-liver). This modality is also useful when the primary tumor site is unknown. In one single-institution retrospective study, it was the most common study ordered to look for an unknown primary tumor site and was able to uncover the primary in 95% of cases.
Magnetic resonance imaging (MRI)
MRI is the best conventional study to detail liver metastases in NETs. It is not as useful as CT for the detection of primary small bowel lesions or their associated lymphadenopathy, but is good for the detection of primary pancreatic NETs. A study comparing MRI, CT and standard somatostatin receptor-based imaging (OctreoScan) reported 95.2% sensitivity for MRI, 78.5% sensitivity for CT and 49.3% sensitivity for the OctreoScan in detecting hepatic metastases. MRI also detected significantly more liver lesions than the other two modalities.
You may see something called Magnetic Resonance Cholangiopancreatography (MRCP). Magnetic resonance cholangiopancreatography (MRCP) is a special type of magnetic resonance imaging (MRI) exam that produces detailed images of the hepatobiliary and pancreatic systems, including the liver, gallbladder, bile ducts, pancreas and pancreatic duct.
The primary role of conventional ultrasound in neuroendocrine disease is detection of liver metastases and estimation of total liver tumor burden. This technique has the advantages of near-universal availability, intraoperative utility, minimal expense and lack of radiation. Most examinations are performed without contrast, which limits their sensitivity (compared with CT and MRI). I know in my own situation, US was used as a quick check following identification of multiple liver metastasis during a CT scan. I’ve also had US used to monitor distant lymph nodes in the neck area but always in conjunction with the most recent CT scan output.
Endoscopic Ultrasound (EUS)
With increased access to endoscopy, NETs in the stomach, duodenum, and rectum are increasingly incidentally detected on upper endoscopy and colonoscopy. Patients are frequently asymptomatic without any symptoms referable to the a NET (i.e. non-functional). EUS has also been used to survey patients at increased risk of developing pancreatic NETs. For example, patients with multiple endocrine neoplasia (MEN). They are also frequently used in conjunction with biopsies using fine needle aspiration (FNA) guided by EUS.
18-Fluoro-Deoxy-Glucose PET (FDG PET) is used to detect malignancy for a variety of tumor types. Unfortunately, its utility has not been borne out in NETs, as the majority of NETs tend to be relatively metabolically inactive and fail to take up the tracer well. However, high-grade NETs are more likely to demonstrate avid uptake of 18FDG, giving these scans utility in identifying tumors likely to display more aggressive behavior.
The use of Fluoro-18-L-Dihydroxyphenylalanine (18F-FDOPA) in PET was developed in the 80’s for the visualisation of the dopaminergic system in patients with degenerative disorders, such as Parkinson’s Disease and related disorders. The ﬁrst publication on the use of 18F-FDOPA PET for brain imaging was in 1983, which was followed by many others on the use of 18F-FDOPA PET for the diagnosis of Parkinson’s disease. Years later, in 1999 the ﬁrst publication on the use of 18F-FDOPA PET for imaging of neuroendocrine tumour appeared. The value of 18F-FDOPA PET has now been proven for the diagnosis and staging of many neuroendocrine tumours, brain tumours and congenital hyperinsulinaemia of infants.
18F-FDOPA is accurate for studying well differentiated tumours. However the difficult and expensive synthesis have limited its clinical employment. It currently can be successfully used for imaging tumours with variable to low expression of somatostatin receptors (SSTR) such as Medullary Thyroid Carcinoma, Neuroblastoma, Pheochromocytoma), and others that cannot be accurately studied with Somatostatin SSTR scans such as the OctreoScan (Somatostatin Receptor Scintigraphy (SRS)), which uses the ligand 111In-DPTA-D-Phe-1-octreotide or the newer 68Ga DOTA-peptides.
Radioiodinated (123I) metaiodobenzylguanidine (MIBG) is an analog of norepinephrine that is used to image catecholamine-secreting NETs such as pheochromocytomas, paragangliomas and glomus tumors. It can also be used to look for Neuroblastoma in children. In patients with functional pheochromocytomas or paragangliomas, this modality has a sensitivity of 90% and positive predictive value of 100%. However, it has limited use in Gastrointestinal (GI) NETs, as this modality was positive in only 49.1% of patients. In the same cohort of patients, OctreoScan was positive in 91.2%. As an imaging tool, this study is best used to confirm a diagnosis of pheochromocytoma or paraganglioma and define the extent of metastatic disease in these tumors. (Note – the Ga68 PET is rising in prominence though). Its most practical use in GI NETs may be to determine whether patients with metastases may benefit from treatment with 131I-MIBG (a form of radiotherapy).
Somatostatin receptor-based imaging techniques
Somatostatin is an endogenous peptide that is secreted by neuroendocrine cells, activated immune cells and inflammatory cells. It affects its antiproliferative and antisecretory functions by binding to one of five types of somatostatin receptors (SSTR1- SSTR5). These are G-protein coupled receptors and are normally distributed in the brain, pituitary, pancreas, thyroid, spleen, kidney, gastrointestinal tract, vasculature, peripheral nervous system and on immune cells. Expression of SSTRs is highest on well-differentiated NETs. Somatostatin receptor type 2 is the most highly expressed subtype, followed by SSTRs 1 and 5, SSTR3 and SSTR4.
It must be noted that even the most modern scans are not an exact science. Radionuclide scans are like conventional imaging, they can be subject to physiological uptake or false positives, i.e. they can indicate suspicious looking ‘glows’ which mimic tumours. This article explains it better than I can – click here.
The ubiquity of SSTRs on NET cell surfaces makes them ideal targets for treatment (e.g. Somatostatin Analogues (Octreotide/Lanreotide) and PRRT), but also for imaging. There are two primary types of somatostatin receptor-based imaging available:
Octreoscan – In111 based
The most common (currently) is the OctreoScan or Somatostatin Receptor Scintigraphy (SRS), which uses the ligand 111In-DPTA-D-Phe-1-octreotide and binds primarily to SSTR2 and SSTR5. In its original form, it provided a planar, full body image. In modern practice, this image is fused with single photon emission computed tomography (SPECT) and CT. This takes advantage of the specificity of the OctreoScan and the anatomic detail provided by SPECT/CT, improving OctreoScan’s diagnostic accuracy. These improvements have been shown to alter the management in approximately 15% of cases, compared with just OctreoScan images. In primary tumors, the OctreoScan’s sensitivity ranges from 35 to 80%, with its performance for unknown primary tumors dipping beneath the lower end of that range (24%). Its ability to detect the primary is limited by the size but not SSTR2 expression, as tumors less than 2 cm are significantly more likely not to localize but do not have significantly different SSTR2 expression than their larger counterparts.
Octreoscan – Tc99m based
In one study, it was shown that sensitivity and negative predictive
values of Tc-99m-Octreotide scan is significantly higher than that of CT
and MRI. Using Tc-99m instead of In-111 had several advantages that
include better availability, cheaper and higher quality images. In
addition, to less radiation exposure to both patients and nuclear
medicine personnel. In the absence of Ga68 PET, this could prove a reliable alternative. Please note this scan is completed in a single day vs In111 Octreotide time of 2-3 days.
Ga68 PET (or SSTR PET in general)
The newest somatostatin receptor-based imaging modality, although it has been around for some time, particularly in Europe. The most common of these labeled analogs are 68Ga-DOTATOC, 68Ga-DOTANOC and 68Ga-DOTATATE. They may be known collectively as ‘SSTR-PET’. Additionally, the DOTATATE version may often be referred to as NETSPOT in USA but technically that is just the commercial name for the radionuclide mix.
These peptides are easier and cheaper to synthesize than standard octreotide-analog based ligands, boast single time point image acquisition compared to 2 or 3 days with Octreoscan. Its superior spatial resolution derives from the fact that it measures the radiation from two photons coincidentally. SPECT, in comparison, measures the gamma radiation emitted from one photon directly. This results in different limitations of detection – millimeters for 68Ga-PET compared with 1 cm or more for SPECT. There are a few choices of ligands with this type of imaging, but the differences lie primarily in their SSTR affinities – all of the ligands bind with great affinity to SSTR2 and SSTR5. 68Ga-DOTANOC also binds to SSTR3. Despite these differences, no single 68Ga ligand has stood out as the clear choice for use in NETs. As with standard somatostatin receptor-based imaging, these 68Ga-PET studies are fused with CT to improve anatomic localization.
Comparison studies between 68Ga-PET and standard imaging techniques (CT, OctreoScan) have universally demonstrated the superiority of 68Ga-PET in detection of NET primary tumors and metastases. Two early studies compared 68Ga-DOTATOC to standard somatostatin imaging (SRS)-SPECT and CT. Buchmann et al. reported that 68Ga-DOTATOC detected more than 279 NET lesions in 27 patients with histologically proven NETs, whereas SRS-SPECT detected only 157. The greatest number of lesions were detected in the liver. 68Ga-DOTATOC found more than 152 hepatic lesions, while SRS-SPECT found only 105, resulting in a 66% concordance rate between the two modalities. The concordance for abdominal lymph nodes was worse at 40.1%. Cleary these advantages are going to impact on treatment plans, some needing to be altered. In addition, 68Ga-DOTA PET imaging can be used to determine which patients might benefit from use of Somatostatin Analogues (Octreotide/Lanreotide) and PRRT – you can read more about this integrated and potentially personalised treatment in my article on ‘Theranostics‘ – click here.
It’s worth pointing out that SSTR PET is replacing previous types of radionuclide scans, mainly Octreoscan (Indium 111) and is not replacing conventional imaging (CI) such as CT and MRI etc. Whilst SSTR-PET has demonstrated better sensitivity and specificity than CI and In-111, there are specific instances in which SSTR-PET is clearly preferred: at initial diagnosis, when selecting patients for PRRT, and for localization of unknown primaries. For patients in which the tumor is readily seen on CI, SSTR-PET is not needed for routine monitoring. The Journal of Nuclear Medicine has just published “Appropriate Use Criteria for Somatostatin Receptor PETImaging in Neuroendocrine Tumors” which gives guidance on it’s use – issued by the Society of Nuclear Medicine and Molecular Imaging (SNMMI).
Parathyroid Scan – Sestamibi
Sestamibi scanning is the preferred way in which to localize diseased parathyroid glands prior to an operation. This parathyroid scan was invented in the early 1990’s and now is widely available. Sestamibi is a small protein which is labeled with the radio-pharmaceutical technetium99 (Tc99m). This very mild and safe radioactive agent is injected into the veins of a patient with hyperparathyroidism (parathyroid disease) and is absorbed by the overactive parathyroid gland. Since normal parathyroid glands are inactive when there is high calcium in the bloodstream, they do not take up the radioactive particles. When a gamma camera is placed over the patient’s neck an accurate picture will show the overactive gland. Only the overactive parathyroid gland shows up…a very accurate test.
The Sestamibi scan will display the hyperactive gland which is causing hyperparathyroidism in about 90 percent (90% sensitivity) of all patients. If the Sestamibi does show the hyperactive gland it is almost always correct (98-100% specificity). It takes approximately two hours to perform the Sestamibi scan after it has been injected. Pictures of the neck and chest are usually taken immediately after the injection and again in 1.75 to 2.0 hours (shown above). Newer techniques allow for more complete two and three dimensional images to be obtained of a patient’s neck. This technique is called SPECT scanning (Single Proton Emission Computerized Tomography) but it is usually not necessary.
Taking the camera inside and directly to the Tumour
Of course there are other ways to “see it” via several types of Endoscopy procedures – taking the camera to the tumour. Read my article about this by clicking here
A look to the future of PET Scans
Just imagine something which is 40 times better than current PET scan technology? That’s what the scientists are working on now. Here’s an example called “EXPLORER“. Clearly there are more answers required in order to see if this is suitable for use with NETs (i.e. will it work with our radionuclide tracers etc) but it is very exciting and like something out of Star Trek. A little bit of me is worried about ‘overdiagnosis’ so interpretation of something that detailed will be very important to avoid unnecessary worry. Read more here and there is a later update here. Check out this cool video of the 3D images:
Please Share this post for Neuroendocrine Cancer awareness and to help another patient
Scanning is a key diagnostic and surveillance tool for any cancer. Even though you have elevated bloods or urine (….or not), a picture of your insides is really like a thousand words…. and each picture has a story behind it. Scanning can be a game changer in the hunt for tumours and although scans can’t (yet) confirm the cancer type and grade, they certainly help with that piece of detective work and are key in the staging of the cancer.
When I read stories of people in a difficult diagnosis, I always find myself saying ‘a scan might resolve this’ and I always suggest people should try to get one. Even in the case of a story about late diagnosis or a misdiagnosis, I find myself thinking ‘if only they had done a scan earlier’. Despite what you read on NET forums, a CT scan will normally find some evidence of most tumour activity.
However, scans are not an exact science…..not yet! Apart from human error, sometimes tumours are too small to see and/or there are issues with ‘pickup’ (i.e. with NETs, nuclear scans need efficient somatostatin receptors). However, technology is improving all the time and you can read about this in my blog Neuroendocrine Cancer – Exciting times Ahead.
As for my own experience, I was very lucky. I managed to get a referral to a specialist early on in my diagnosis phase. He looked at the referral notes and said “what are you doing this afternoon”. I replied “whatever you want me to do”. He wanted to scan me. He didn’t know I had cancer but his instincts led him to believe he needed to see inside my body. The scan results were pretty clear – I had a metastatic Cancer and further checks were now needed to ascertain exactly what it was. So I took my seat on the rollercoaster. Here’s something I always say I believe is so much better than the impractical early diagnosis messages that seem to pervade our community: If your doctors don’t suspect something, they won’t detect anything and I believe this is a very frequent outcome of many diagnoses for many cancers (not just NETs).
There’s frequent discussion about the best types of scans for different types of NETs and even for different parts of the anatomy. This is correct and there’s also different views on the subject (including in the medical community), However, a few well known facts that can be gleaned from authortative NET sources. I found this useful video summary from the NET Patient Foundation describing the different scans for NET Cancer and what to expect. Worth a look.
Sooner we can all get access to the latest radionuclide scans the better!
“I’m only as good as my last scan”. I received this comment last week in response to one of my posts and I thought it was a very pragmatic thing for someone to say.
A NET patient under surveillance has regular tests at determined intervals but the one that is most likely to spot disease progression, stability or regression is a scan. Markers such as (say) Chromogranin A (CgA) or 5HIAA are clearly useful but in an ongoing surveillance scenario, they alone would not be used as a firm declaration of progression, stability or regression. Every picture tells a story and a scan is normally the confirmation required whether it’s a CT, MRI or PET (etc).
Scans are also important at the diagnostic phase and I’m sure like myself, many people had their first ever scan at this point. You can have many checks, investigations and tests but for most, the scan is normally the main test that is going to confirm the presence of tumours. This then leads to further checks to confirm the staging and grading (i.e. a biopsy) and then hopefully, a proper diagnosis.
I don’t mind scans, they are probably the test that is going to alert my team to anything odd going on. Thus why I don’t mind doing them – in fact, they are a piece of cake!