Neuroendocrine Cancer: a needle in a haystack


needle in a haystack

It’s no secret that Neuroendocrine Cancer can be difficult to diagnose. Although earlier diagnosis is improving (as reported in the SEER database report issued in 2017), there is still a lot of ground to cover. It’s also no secret that certain cancers are difficult to diagnose (NETs is one) and there are a number of reasons why this happens, including but not limited to: – they grow silently, they often produce vague symptoms which can be mistaken for much more common illnesses, and their complexity is not fully understood.

I wanted to cover two different aspects of the problem of finding NETs. Firstly, in finding the primary tumour so that the type of NET can be properly established – this drives the best treatment regime. Secondly in finding all the tumours, as this establishes the correct and most detailed staging declaration – this drives treatment plans and surveillance regimes that need to be put into place.

Hunting Tumours – Primary vs Secondary

It’s really important to determine which tumours are primary and which are secondary (metastasis). There’s a number of ways to help work this out and knowledge of NETs epidemiology studies can help.

Specialist Knowledge – certain things are known about the behaviour of NETs

Specialists and in particular NET specialists will be aware of the vagaries of NETs in terms of what tumours are normally a primary and which are normally secondary and many of the pitfalls involved in working that out. Many NETs will have metastasized to the liver at diagnosis, so whilst it is not impossible to have a primary liver NET, the vast majority of liver tumours found will be secondary (metastases). NET Specialists are more likely to have the experience than generalists. They know that the varying metastatic potential depending on the primary site clearly indicates differing biology and genetics across sites and they know that NETs are indeed a heterogeneous group of tumours. The differences cannot be explained by whether the NET is situated in the foregut, midgut, or hindgut. For example, Appendiceal NET is known to be less prone to metastasis. This may be due to the high rate of incidental findings during appendectomies, or because the appendix is an immunological organ where malignant cells can therefore be expected to be frequently recognized by the immune system.

The majority of the digestive tract is drained by the portal venous system, explaining the dominance of liver metastases in this group of tumours. This also explains our finding that many nervous system and bone metastases originate from NETs in the lungs. Disseminated tumour cells may directly reach the systemic circulation from the lungs, whereas if originating from the midgut region, they need to first pass both the liver and the lungs.

As an example of this heuristic knowledge, one Swedish study indicated that two-thirds of peritoneal metastases will be attributed to Small Intestine NETs (SI NETs). SI NETs and Pancreatic NETs (pNETs) are the most likely to metastasize. The least likely sites to metastasize are the Appendix and Rectum. The same study indicated that in addition to the common metastatic locations of lymph nodes and liver, Lung NETs are more likely to metastasize to the brain and bone than other types. I believe the findings from this study more or less correlates to other information I’ve had access to and also confirms the technical behaviour paragraph above.

Multiple Primary Tumours

With NETs there are two scenarios:

1. Multiple primaries in same organ/location (multicentric). This is fairly common in small intestine (SI NETs), stomach/gastric NETs (gNETs), and also found in Lung and pNETs too. NET experts will be aware of the issue and know to look for the possibility. This is an important point with SI NETs as it’s quite long although held together by the mesentery, so a ‘Mark 1 eyeball’ can be more efficient in finding NETs in this organ than scans.  There is a very well known surgical technique called “running the bowel” where they check the small intestine for signs of other primary tumours – they can do the same with the large intestine.  Additional surgeries due to this lack of knowledge could come with significant morbidity. Multiple ‘nodes’ and ‘lesions’ are common in the thyroid.

2. Multiple primaries in different locations. This is common with Multiple Endocrine Neoplasia (MEN) syndromes (the name gives it away) and these may be metasynchronous. MEN1 for example can have tumours in what is called the ‘3 P’ locations, pituitary, pancreas and parathyroid. Of course MEN guys may also have multiple primaries in the same organ (multicentric).  Read more about MEN by clicking here.

There’s probably a third scenario (for all cancers) and that is multiple primaries with different cancers (i.e a second, third and fourth cancer etc). Synchronous would be really unlucky but metasynchonous is more likely and there are many NET patients with a second cancer.

What else helps find a NET? 

There are many other clues open to those involved in diagnosing a NET:

Patient. Very often the patient plays a big part of determining where the primary and other tumours might be by carefully describing symptoms.

Incidental Finds. NETs are very often found incidentally during trips to the ER/A&E and also during tests for something else. This is particularly the case with Appendiceal NETs and might explain why the average age of a patient is significantly lower in this type of NET.

Blood tests and Hormone Markers. We are not yet in a position where these types of tests can diagnose (but we are moving in that direction). In the case of unknown primaries (CUP), sometimes test results can help to find where some of these cancers started. With NETs, symptomatic patients can often test to confirm an elevated hormone marker which may narrow it down to a specific organ or gland. Read more here.

Scans and Endoscopies. Most cancers of a certain size may show up on conventional scanning such as CT, MRI and Ultrasound. Nuclear scans are now playing a bigger part in finding tumours which betray their location through functional behaviour by lighting up or glowing on these imaging devices. Endoscopies (e.g. gastroscopies, colonoscopies, even gastro intestinal pill cameras can be used) can help but like scans are not foolproof). Generally with NETs, if you can see it, you can detect it. Read more here.

Hereditary Conditions. Around 5-10% of NETs are hereditary in nature, mostly involving the MEN group of syndromes. Many of those people will know they are at risk of developing NETs and their doctors should know the most common locations for primary tumours associated with each gene. So a declared or suspected hereditary syndrome is useful in finding primary tumours if they exist and are proving difficult to find.

Biopsies. “Tissue is the issue”. Pathology can very often give really strong clues as to the type of NET and therefore the likely location of a primary tumour, for example additional tests such as immunostains. Many biopsies will come from secondary cancer (metastases), mostly the liver.  Despite all the potential diagnostic routes above, the place the cancer started is sometimes still not found and this may lead to atypical diagnostic/treatment plans and in certain cases this might even include exploratory biopsies via surgery (invasive/minimally invasive), perhaps combined with opportunistic tumour removal if found during the procedure.

Staging. Simple staging can be given if locations of metastases are known. For example in the case of Liver metastases, the stage is automatically Stage 4. However, the full staging definition relies on knowing distant metastases, loco-regional metastases and the full Tumour/Node/Metastases (TNM) definition (size, spread, etc) cannot be fully complete without a primary. Read more here.

Cancers of Unknown Primary

Cancer is always named for the place where it started, called the primary site. Sometimes doctors can’t tell where a cancer may have started. When cancer is found in one or more places where it seems to have spread, but the site where it started is not known, it is called a cancer of unknown primary (CUP) or an occult primary cancer.

When you look at the ratio of all cancers, the figure for cancers of unknown primary (CUP) is quite startling. Depending on where you look the figure is around 2-10%. That doesn’t seem a lot but when you consider the amount of people diagnosed with cancer, the total figure must be staggering. Interestingly, Cancer Research UK say that 60% of CUP cases are in the over 75s. In another interesting Swedish study, doctors claimed that the rates of metastatic cases were higher with certain NETs than they were in their anatomical counterparts, reinforcing the dangerous and sneaky nature of NETs.

Despite quite advanced scanning and diagnostic testing currently in place, and the extensive knowledge of NET specialists, there can still be reasons for not being able to find the primary tumour:

  • The primary is just too small to be seen and is growing quite slow. Very small cancers might not cause symptoms or be seen on scans. This is a particularly relevant point with NETs.
  • The primary could be hidden in tissue in between different organs causing confusion about the actual primary location.
  • The body’s immune system killed the primary cancer. It’s also possible (but not common) that any secondary cancer (i.e. metastases) is still growing.
  • The tumour has become loose from its primary location and exited the body, e.g. from a wall of the bowel and excreted out in the stool.
  • The primary cancer was removed during surgery for another condition and doctors didn’t know cancer had formed. For example, a uterus with cancer may be removed during a hysterectomy to treat a serious infection.

Summary

I hope this is useful for many NET patients, particularly those who are looking for a diagnosis or looking for a primary tumour.

Neuroendocrine Cancer – at times, it can really be like looking for a needle in a haystack.

Thanks for reading

Ronny

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ASCO 2017 – Let’s talk about NETs #ASCO17

ASCO (American Society of Clinical Oncology) is one of the biggest cancer conferences in the world normally bringing together more than 30,000 oncology professionals from around the world to discuss state-of-the-art treatment modalities, new therapies, and ongoing controversies in the field.  As Neuroendorine Tumors is on a roll in terms of new treatments and continued research, we appear to be well represented with over 20 ‘extracts’ submitted for review and display.  This is fairly complex stuff but much of it will be familiar to many.  I’ve filtered and extracted all the Neuroendocrine stuff into one list providing you with an easy to peruse table of contents, complete with relevant linkages if you need to read more.  For many the extract title and conclusion will be sufficiently educational or at least prompt you to click the link to investigate further.  Remember, these are extracts so do not contain all the details of the research or study. However, some are linked to bigger trials and linkages are shown where relevant.  I’ve also linked to some of my blog posts to add context and detail.

I’m hoping to capture any presentations or other output from the meeting which appears to be relevant and this will follow after the meeting.  I will also be actively tweeting any output from the live event (for many cancers, not just NETs).

There’s something for everyone here – I hope it’s useful.

68Ga-DOTATATE PET/CT to predict response to peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumours (NETs).  

Conclusions: Objective response to PRRT defines a subset of patients with markedly improved PFS. SUVave 21.6 defines a threshold below which patients have a poor response to PRRT. This threshold should be taken forward into prospective study.

Check out my recent blog discussing ‘Theranostic pairing” – click here

Rohini Sharma 4093
A multicohort phase II study of durvalumab plus tremelimumab for the treatment of patients (PTS) with advanced neuroendocrine neoplasms (NENs) of gastroenteropancreatic (GEP) or lung origin (the DUNE trial-GETNE1601-).

News of a trial – no conclusion included.  However, see trial data NCT03095274

Ignacio Matos Garcia TPS4146
Association between duration of somatostatin analogs (SSAs) use and quality of life in patients with carcinoid syndrome in the United States based on the FACT-G instrument.

Conclusions: The duration of SSA use was positively associated with QoL benefit among CS patients. This may be explained by long-term effectiveness of SSAs or selection bias favoring patients with more indolent disease. Future studies will be needed to distinguish between these possibilities.

Daniel M. Halperin e15693
Association of weight change with telotristat ethyl in the treatment of carcinoid syndrome.

Conclusions: The incidence of weight gain was dose-related on TE and was greater than that on pbo. It was possibly related to a reduction in diarrhea severity, and it may be a relevant aspect of TE efficacy among patients with functioning metastatic NETs. Clinical trial information: NCT01677910

See my blog post Telotristat Ethyl

Martin O Weickert e15692
Blood measurements of neuroendocrine tumor (NET) transcripts and gene cluster analysis to predict efficacy of peptide radioreceptor therapy.

Conclusions: A pre-PRRT analysis of circulating NET genes, the predictive quotient index comprising “omic” analysis and grading, is validated to predict the efficacy of PRRT therapy in GEP and lung NETs.

Lisa Bodei 4091
Capecitabine and temozolomide (CAPTEM) in neuroendocrine tumor of unknown primary.

Conclusions: CAPTEM shows activity in neuroendocrine tumor of unknown primary. Currently FDA approved treatment options for grade I and grade II GI NETs includes somatostatin analogs and everolimus. Both of which are cytostatic and of limited use in case of visceral crisis or bulky disease where disease shrinkage is required. CAPTEM should be considered for grade II NETS of unknown primary.

Aman Chauhan e15691
Clinical and epidemiological features in 495 gastroenteropancreatic neuroendocrine patients in Mexico.

Conclusions: This is the first multi-center study in Mexico. Which reflects the clinical characteristics of the NET_GET. The results differ in their epidemiology from that reported in other countries. However, the clinical and therapeutic results are very similar.

Rafael Medrano Guzman e15687
Effect of lanreotide depot (LAN) on 5-hydroxyindoleacetic acid (5HIAA) and chromogranin A (CgA) in gastroenteropancreatic neuroendocrine (GEP NET) tumors: Correlation with tumor response and progression-free survival (PFS) from the phase III CLARINET study.

Conclusions: These data suggest that serotonin is secreted by nonfunctioning tumors, but does not reach the threshold required for clinical carcinoid symptoms. Monitoring 5HIAA and CgA may be useful during LAN treatment of nonfunctional GEP NETs. Clinical trial information: NCT00353496

Alexandria T. Phan 4095
Final progression-free survival (PFS) analyses for lanreotide autogel/depot 120 mg in metastatic enteropancreatic neuroendocrine tumors (NETs): The CLARINET extension study.

Conclusions: CLARINET OLE suggests sustained antitumor effects with LAN 120 mg in enteropancreatic NETs irrespective of tumor origin, and suggests benefits with LAN as early treatment. Clinical trial information: NCT00842348

Edward M. Wolin 4089
Lanreotide depot (LAN) for symptomatic control of carcinoid syndrome (CS) in neuroendocrine tumor (NET) patients previously responsive to octreotide (OCT): Subanalysis of patient-reported symptoms from the phase III elect study.

Conclusions: Pts showed improvement in CS symptoms of flushing and diarrhea and reduction in 5HIAA levels with LAN treatment, indicating efficacy of LAN regardless of prior OCT use. Transition from OCT to LAN was well tolerated among prior OCT pts in ELECT. Clinical trial information: NCT00774930

Check out my blog post about Lanreotide and Lanreotide vs Octreotide

George A. Fisher 4088
Molecular classification of neuroendocrine tumors: Clinical experience with the 92-gene assay in >24,000 cases.

Conclusions: These findings highlight the utility of molecular classification to identify distinct NET tumor types/subtypes to improve diagnostic precision and treatment decision-making. In addition, significant differences in the distribution of molecular diagnoses of NET subtype by age and gender were identified.

Andrew Eugene Hendifar e15700
Multi-omic molecular profiling of pancreatic neuroendocrine tumors.

Conclusions: In PNETS, multi-omic profiling through the KYT program identified targetable alterations in several key pathways. Outcome data will be explored.

Rishi Patel e15685
Outcomes of peptide receptor radionuclide therapy (PRRT) in metastatic grade 3 neuroendocrine tumors (NETs).

Conclusions: In this poor prognosis G3 NET cohort of whom 77% had received prior chemotherapy, a median OS of 18 months from start of PRRT is encouraging and warrants further study. PRRT is a promising treatment option for patients with G3 NET with high somatostatin-receptor expression selected by SSRI.

Mei Sim Lung e15694
Periprocedural management of patients undergoing liver resection or liver-directed therapy for neuroendocrine tumor metastases.

Conclusions: Occurrence of documented carcinoid crisis was low in this high-risk population. However, a significant proportion of patients developed hemodynamic instability, suggesting that carcinoid crisis is a spectrum diagnosis and may be clinically under-recognized. Use of octreotide was not associated with risk of carcinoid crisis or hemodynamic instability; however, this analysis was limited by our modest sample size at a single institution. There remains a need to establish an objective definition of carcinoid crisis and to inform standardization of periprocedural use of octreotide for at-risk patients.

See my blog on “Carcinoid Crisis” 

Daniel Kwon e15689
Predictive factors of carcinoid syndrome among patients with gastrointestinal neuroendocrine tumors (GI NETs).

Conclusions: By assessing patients with GI NET from two independent US claim databases, this study suggested that patients diagnosed with CS were 2-3 times more likely to be diagnosed with liver disorder, enlargement of lymph nodes, or abdominal mass, than those without CS during the one year prior to CS diagnosis. Future studies using patient medical charts are warranted to validate and interpret the findings. These findings, when validated, may aid physicians to diagnose CS patients earlier.

Beilei Cai e15690
Predictors of outcome in patients treated with peptide radio-labelled receptor target therapy (PRRT).

Conclusions: Radiological progression within 12 months of completion of PRRT is associated with a worse outcome in terms of OS. Patients with greater liver involvement and highest CgA levels are more likely to progress within 12 months of treatment completion. Earlier treatment with PRRT in patients with radiological progression not meeting RECIST criteria may need to be considered. There may be a greater survival benefit if PRRT is given prior to the development of large volume disease.

Dalvinder Mandair 4090
Pre-existing symptoms, resource utilization, and healthcare costs prior to diagnosis of neuroendocrine tumors: A SEER-Medicare database study.

Conclusions: To the best of our knowledge, this is the first population-based study to examine potentially relevant pre-existing symptoms, resource utilization and healthcare costs before NET diagnosis. NET patients were more likely to have certain conditions and incurred higher resource utilizations and costs in the year preceding diagnosis of NET.

Chan Shen 4092
Prevalence of co-morbidities in elderly patients with distant stage neuroendocrine tumors.

Conclusions: This population-based study showed that elderly NET pts have significantly different prevalence of co-morbidities compared to non-cancer controls. The impact of these conditions on survival and therapeutic decisions is being evaluated.

A. Dasari e15699
Prognostic factors influencing survival in small bowel neuroendocrine tumors with liver metastasis.

Conclusions: In patients with SBNET with liver metastasis, higher tumor grade and post-operative chemotherapy increased risk of death. However, resection of the primary tumor along with liver metastasis improves the 5-year OS with complete cytoreduction providing the most benefit.

Nicholas Manguso e15688
Role of 92 gene cancer classifier assay in neuroendocrine tumor of unknown primary.

Role of 92 gene cancer classifier assay in neuroendocrine tumor of unknown primary. | 2017 ASCO Annual Meeting Abstracts

Conclusions: Tissue type ID was able to identify a primary site in NETs of unknown primary in majority (94.7%) of cases. The result had direct implication in management of patients with regards to FDA approved treatment options in 13/38 patients (pNETs, merkel cell and pheochromocytoma).

Aman Chauhan e15696
Surgery in combination with peptide receptor radionuclide therapy is effective in metastatic neuroendocrine tumors and is definable by blood gene transcript analysis.

Conclusions: Radical loco-regional surgery for primary tumours combined with PRRT provides a novel, highly efficacious approach in metastasised NET. The NETest accurately measures the effectiveness of treatment.

Andreja Frilling e15697
The impact of pathologic differentiation (well/ poorly) and the degree of Ki-67 index in patients with metastatic WHO grade 3 GEP-NECs.

Conclusions: Grade 3 GEP-NECs could be morphologically classified into well and poorly differentiated NETs. Additionally, among grade 3 GEP-NECs, there was a significant difference in ranges of Ki67 index between well and poorly differentiated NECs. Higher levels ( > 60%) of Ki67 index might be a predictive marker for efficacy of EP as a standard regimen in grade 3 GEP-NECs.

Check out my blog post on Grading which has incorporated latest thinking in revised grade 3 classification

Seung Tae Kim e15686
Theranostic trial of well differentiated neuroendocrine tumors (NETs) with somatostatin antagonists 68Ga-OPS202 and 177Lu-OPS201.

Conclusions: In this trial of heavily treated NETs, preliminary data are promising for the use of 68Ga-OPS202/177Lu-OPS201 as a theranostic combination for imaging and therapy. Additional studies are planned to determine an optimal therapeutic dose and schedule. Clinical trial information: NCT02609737

Diane Lauren Reidy 4094
Use of antiresorptive therapy (ART) and skeletal-related events (SREs) in patients with bone metastases of neuroendocrine neoplasms (NEN).

Conclusions: SREs in NEN patients with BM were not uncommon, especially in patients with grade 3 NEN and osteolytic metastases. Application of ART did not significantly alter median OS or TTSRE, no subgroup with a benefit of ART could be identified. The use of ART in NEN should be questioned and evaluated prospectively.

Leonidas Apostolidis 4096
Targeted radiopeptide therapy Re188-P2045 to treat neuroendocrine lung cancer

Conclusions: Rhenium Re 188 P2045, a radiolabeled somatostatin analog, may be used to both identify and treat lung cancer tumors. The ability to image and dose patients with the same targeted molecule enables a personalized medicine approach and this highly targeted patient therapy may significantly improve treatment of tumors that over express somatostatin receptor.

Christopher Peter Adams, Wasif M. Saif e20016

Thanks for reading

Ronny
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