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.
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
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.
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
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.
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.
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.
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
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
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
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.
Conclusions: In PNETS, multi-omic profiling through the KYT program identified targetable alterations in several key pathways. Outcome data will be explored.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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 Gradingwhich has incorporated latest thinking in revised grade 3 classification
Seung Tae Kim
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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
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.
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.
5 years ago today, I had a bunch of lymph nodes removed. Two separate areas were resected, only one was showing growth but both were showing up as hotspots on an Octreoscan. I had known since shortly after diagnosis in 2010 that ‘hotspots’ were showing in my left ‘axillary’ lymph nodes (armpit) and my left ‘supraclavicular fossa’ (SCF) lymph nodes (clavicle area). Some 10 months previously, I had a major liver resectionand 5 months prior to the liver resection, I had a small intestinal primary removedincluding work on some associated complications. There had always been a plan to optimise cytoreduction of my distant metastases, it was just a matter of timing. I still can’t get my head round why metastases from a small intestinal NET managed to get to this area but not others!
Distant nodal metastasis treatment
A total of 9 nodes were removed from my left armpit (a very common operation for breast cancer patients). The surgeon had inspected the area and found some were palpable and my normally stable Chromogranin Amarker was showing a small spike out of range. During the same operation under general anaesthetic, an ultrasound directed SCF nodal ‘exploration’ was carried out. When biopsied, 5 of the 9 resected axillary nodes were tested positive (Ki-67 <5) but the 5 SCF nodes removed were tested negative. The subsequent Octreoscan still lit up in the left SCF area but the lights on the left axillary area were ‘extinguished’. There is no pathological enlargement or pain in the left SCF area – so this is just monitored.
Side effects
Apart from a very faint scar in the left SCF area, there does not appear to be any side effects from this exploratory surgery. The left axillary area cut is well hidden by hair growth but I do sense a lack of feeling in the area. Additionally, I have a very mild case of lymphedema in my left hand which occasionally looks slightly swollen – the consequences of cancerand its treatment. Fluid build-up, or post-operative seroma, can be a side effect of a lymphadenectomy. In fact, within a month of the operation, I had to have circa 160mls of fluid removed on 4 occasions from my armpit. It was uncomfortable and painful, resulting in additional time off work. The surgeon used a fine needle aspiration to draw out the fluid, a painless procedure. It eventually cleared up and everything was back to normal. The specialist said my left arm would be slightly more susceptible to infections and suggested to avoid using my left arm for blood draws and other invasive procedures and injuries.
Other close calls (“to cut or not to cut”)
I have a 19mm thyroid lesion which was pointed out to me in 2013. This has been biopsied with inconclusive results. Although the thyroid is an endocrine gland, it looks like a non-NET problem so far. Thyroid nodules are in fact very common and statistically, 50-70% of all 50-70 year olds will have at least one nodule present (i.e. if you are in your 50s, there is a 50% chance you will have one nodule and so on). The vast majority will never bother a person while they live. I attend an annual Endocrine MDT where this is monitored in close coordination with the NET MDT. It’s actually managed by the same surgeon who carried out the nodal work above.
I have a 3mm lung nodule, discovered in 2011. Apparently, lung nodules are a pretty common incidental finding with 1 per 500 X-rays and 1 per 100 CT scans finding them. This is monitored and hasn’t changed since noted.
A fairly common disposition of metastatic Neuroendocrine Tumours (NETs) is a primary with associated local/regional secondary’s (e.g. lymph nodes, mesentery and others) with liver metastases. Technically speaking, the liver is distant. However, many metastatic patients have additional and odd appearances in even more distant places, including (but not limited to) the extremities and the head & neck. In certain NETs, these might be an additional primary (e.g. in the case of Multiple Endocrine Neoplasia (MEN); or they could even be a totally different cancer. The worry with NETs is that the ‘little suckers‘ can sometimes make these surprise appearances given that neuroendocrine cells are everywhere.
Cancer doesn’t just spread through the blood steam, it can also spread through the lymphatic system. This is a system of thin tubes (vessels) and lymph nodes that run throughout the body in the same way blood vessels do. The lymph system is an important part of our immune system as it plays a role in fighting bacteria and other infections; and destroying old or abnormal cells, such as cancer cells. The lymphatic system also contains organs, some of which feature regularly in NETs. If cancer cells go into the small lymph vessels close to the primary tumour they can be carried into nearby lymph glands where they stick around. In the lymph glands they may be destroyed (that is actually one of the jobs of the lymph glands) but some may survive and grow to form tumours in one or more lymph nodes.
The Lymphatic System
I also had the usual bulky chains of lymph node metastases in or around the mesentery that frequently appear with an abdominal primary (in my case the small intestine). These were all removed as part of my primary resection. However, I knew since shortly after diagnosis in 2010 that I had ‘hotspots’ in my left ‘axillary’ lymph nodes (armpit) and my left ‘supraclavicular fossa’ (SCF) lymph nodes (clavicle). These were found on Octreoscan but at the time, they were not pathologically enlarged – just ‘lighting up’. They also light up on Ga68 PET.
In early 2012, 15 months after removal of primary and 10 months after liver resection, one of the axillary lymph nodes became palpable (signs of growth) and this coincided with a small spike in Chromogranin A. A total of 9 nodes were removed very shortly after this surveillance, 5 of which tested positive for NETs (Ki-67 <5%). As part of the same operation, 5 SCF left clavicle nodes were removed but tested negative. On a subsequent Octreoscan, the armpit was clear but the clavicle area still lit up. However, there is no pathological enlargement or pain – so this is just monitored. Also lights up on Ga68 PET I have a 3mm lung ‘nodule’, discovered in 2011. Apparently, lung nodules are a pretty common incidental finding with 1 per 500 X-rays and 1 per 100 CT scans finding them. This is monitored.
I have a 19mm thyroid ‘lesion’ which was pointed out to me in 2013. This has been biopsied with inconclusive results. Although the thyroid is an endocrine gland, it looks like a non-NET problem to date. Thyroid nodules are in fact very common and statistically, 50-70% of all 50-70 year olds will have at least one ‘nodule’ present (i.e. if you are in your 50s, there is a 50% chance you will have one nodule and so on). The vast majority will never bother a person while they live. That said, my thyroid blood tests are abnormal and on 20th March 2018, following an Endocrine appointment, I was put on a trial dose of 50mcg of Levothyroxine to counter the thyroid panel results indicating hypothyroidism. Levothyroxine is a thyroid hormone replacement. Early in 2017, during my Endocrine MDT, a surveillance ultrasound spotted a slightly enlarged lymph node on the right side (measuring 9mm x 9mm) described as a ‘level 4’ node (a location indicator meaning the ‘lower jugular group’). The report was passed to the NET MDT for their consideration with the surgical rep on the Endocrine MDT recommending a conservative approach – the NET MDT agreed. I suspect that’s right, it’s still below the worry threshold, nothing is palpable (no lumps) and I don’t have any specific symptoms. There could have been a number of reasons for the enlargement and it might even be back to normal size on my next scan (spoiler alert – it was). All my issues have been left-sided to date, so that was interesting. That said, I did have an MRI in 2014 to investigate pain and a swelling at the site of my right ‘sternoclavicular’ joint – subsequently declared a non-issue. Showed as inflammation on recent Ga68 PET.
Life as a metastatic Neuroendocrine Cancer patient is interesting and efficient surveillance is absolutely critical.
One of the most discussed and sometimes confusing subjects on forums is the staging and grading of Neuroendocrine Neoplasms (NENs). Mixing them up is a common error and so it’s important to understand the difference despite the apparent complexity. If I was to make a list of questions for my specialist/Oncologist at diagnosis, it would include “What is the stage, grade and differentiation of my cancer”. To enable me to synchronise with the documented guidance, I’m going to use the following WHO 2017 approved terms in this post:
Neuroendocrine Neoplasm (NEN) – all types of Neuroendocrine tumour of whatever grade (please note Neoplasm is another word for tumour)
Neuroendocrine Tumour (NET) – all well-differentiated tumours (an explanation of differentiation will be provided below)
Neuroendocrine Carcinoma (NEC) – all poorly differentiated tumours
Stage vs Grade
In the most basic of terms, stage is the spread or extent of cancer and grade is the aggressiveness of cancer. They are totally different things and an understanding of both is important as they are critical to predict outcome (to a certain extent) and guide therapy. There is no correlation between the two, you can have the lowest grade with the highest stage (actually very common with NETs).
As patients, we deal with many medical specialists during diagnosis and subsequent treatment. However, we rarely meet the pathologist who plays a critical role in the outcome. Precise diagnosis is what drives patient decisions and treatment. If the pathology is wrong, everything that follows could be incorrect as well. It’s a very important area.
Why is differentiation important?
To fully understand grading, you also need to understand the concept of ‘differentiation’. In the most basic of terms, ‘differentiation’ refers to the extent to which the cancerous cells resemble their non-cancerous counterparts. This is an important point for NETs because many low-grade tumour cells can look very similar to normal cells. The differentiation of a NET has an impact on both prognostics and treatment regimes.
NENs fall into one of three grades based on their differentiation and their proliferative rate. The proliferative rate is measured mainly using two methods known as Miotic Count and Ki-67 index, the latter seems to be more frequently used (but see below for Lung NETs). The Ki-67 index can usually be determined, even in cases of small biopsies but Mitotic rate counting requires a moderate amount of tumour tissue (at least 50 HPFs or 10 mm) and may not be feasible for small biopsies. The Miotic Count method may be preferred or used in addition to Ki-67 for certain Lung NET scenarios as it is said to be more helpful in distinguishing atypical from typical NET (what some might ‘old fashionably’ and incorrectly refer to as Lung Carcinoid tumours), and for small and large cell lung Neuroendocrine Carcinomas (NEC).
Some of you may have heard the term ‘moderately differentiated’ which tended to align with an intermediate grade or Grade 2. However, please note that the term moderately differentiated as a classification was phased out in 2010 by WHO reducing from 3 differentiation levels to 2. Grade 2 is also defined as well differentiated but based on different proliferative rate (see table). High grade was normally referred to as Neuroendocrine Carcinoma indicating it is a faster growing and more aggressive cancer. However, see below for an important change to high grade classification.
Grading – Key WHO 2017 Changes
WHO Classifications of Cancer are published in something known in medical world as “The Blue Book”. For NETs, the 2017 version comprises only the “WHO Classification of Tumours of Endocrine Organs”. Technically this would preclude the digestive system and lung NETs but I’m told on good authority from world leading pathologists and from listening to lectures at ENETS 2018, that the classification in the leading picture is to be used for all NENs. Worth also noting that the latest ENETS Guidelines are already using the new grading terms. Many sites remain out of date so be careful where you look.
The 2017 World Health Organisation (WHO) classification sub-divided Grade 3 into two new entities: a well differentiated high-grade NET and a poorly differentiated high-grade NEC. There may also be a cut-off point in proliferative rate (i.e. Ki-67) between NET and NEC in relation to potential treatment strategies (55% is mentioned for pNETs but I’m currently investigating).
The Grade 1 to 2 Ki-67 cut-off is changed from 2 to < 3 for clarification purposes. There was some discussion as to whether it should be <5 but this was not accepted.
Well differentiated High Grade NETs are now recognised. These are known as a NET rather than a NEC. Both Grade 3 (NET) and Grade 3 (NEC) have the same biopsy marker cut-offs as per the leading slide but it is thought that a threshold reading of 55% could have some influence on the treatment regime. For example, a well differentiated tumour with a Ki67 of less than 55% might benefit from the same treatment given to Grade 1 or 2 patients, whereas a well differentiated tumour with a Ki67 of more than 55% might benefit from the same treatment given to poorly differentiated NEC. Only a guideline and I suspect this is like many things in NENs, very individual, relies on many factors, so your specialist will drive this accordingly. You may see these 2 grades listed as Grade 3a for NET and Grade 3b for NEC.
Previously, Pheochromocytoma did not have an official grading regime, i.e. they were just benign or malignant. Now they are using the same grading system as above. I’m assuming this is the same for Paraganglioma and I will confirm in due course. This is an excellent change and a continuation from the WHO 2010 classification where there was great emphasis away from a benign/malignant classification to formal grade levels on the basis that all NETs have malignant potential.
It also introduced a change to the naming of mixed cell tumours from Mixed AdenoNeuroendocrine Carcinoma (MANEC) to Mixed Neuroendocrine Non-Neuroendocrine Neoplasms (MiNEN). A full explanation of this MiNEN will follow but I would suggest the use of the term ‘Neoplasm’ has been chosen rather than ‘Carcinoma’ is because these neoplasms can be well or poorly differentiated.
It’s not possible at this time to acquire copies of the official output but I will keep this blog live.
The source material for the 2017 version of this article.
From leading Pathologist Dr Anthony Gill – Remember this is based on Endocrine Organs only but it will eventually apply to all. I am awaiting access to free documentation to update this article further – only ones I can currently find are not free!
Misc Grading Issues
The proliferative rate can be diverse in NENs, so sampling issues can limit the accuracy of grading. More substantial samples of tumour are therefore preferable for grading thus why the Ki-67 index is preferred for biopsies where large amounts of tissue may not be available. The distinction of low-grade from intermediate grade can be challenging when using small samples. A couple of interesting observations about NET grading which I spotted during my research and ‘forum watching’. You can have multiple primary tumours and these might have different Ki-67 scores. Additionally, on larger tumours, Ki-67 scores can be different on different parts of the tumour. And something I know from my own experience, secondary tumours can have different Ki-67 scores than primary – even a different grade. In my own case, my liver secondary tumours were graded higher than my primary which according to my surgeon is in keeping with a clone of the disease having become more aggressive over time. Royal Free Hospital NET Centre indicates a person’s grade should be taken from the highest biopsy grade taken. This is a fairly complex area but a recent study published by the US National Institute of Health and many anecdotal comments made by NET specialists indicates that is a fairly common scenario.
Staging (spread)
Staging is the extent or spread of disease. Most types of cancer have 4 stages, numbered from 1 to 4 indicating a rising spread as the number is bigger. Often doctors write the stage down in Roman numerals, perhaps this is to stop any confusion between standard numbers used for Grades? So you may see stages written as I, II, III and IV. In addition to this standard method, there is also an agreed model known as TNM (Primary Tumour, Regional Node, Distant Metastasis) which is essentially a more detailed staging definition when combined with the Stage 1-4 model. Please note with TNM models, there could be different stage descriptions depending on the location of the primary tumour and similarly different TNM models for different tumour locations.
WHO 2017 changes
WHO 2017 has recommended enhancements to the TNM system mainly the use of additional suffixes indicating the extent of lymph node involvement. Details to follow when I can free access.
The following example shows the stage descriptions for a NET of the small intestine (the others are similar but worded accordingly for that part of the anatomy):
Stage I tumour is less than 1 cm in size and has not spread to the lymph nodes or other parts of the body.
Stage II tumour is greater than 1 cm in size and has started to spread beyond the original location, but has not spread to the lymph nodes or other parts of the body.
Stage III is any size tumour that has spread to nearby areas of the body and also to at least one lymph node.
Stage IV is any size tumour that has spread to one or more lymph nodes and has also spread to other, more distant areas of the body (such as the liver).
It’s also worth pointing out that Stage IV does not necessarily mean a cancer is more dangerous than other cancers of lesser stages. This is an important point for NETs where Stage 4 can be matched up with a low-grade tumour i.e. Stage 4 for lower grade NETs is very often not the ‘red flag’ it is for other more aggressive cancers. For example, doctors may surgically remove a Stage IV NET, while surgery might not help a patient with a cancer of a higher grade at such a late stage.
Notes:
Sometimes doctors use the letters to further divide the number categories – for example, stage 2A or stage 3B. This is normally to clarify or provide more detail of the primary tumour size/invasion in conjunction with the TNM model.
You may also see something called Stage 0 which is for ‘Carcinoma in situ’. It means that there is a group of abnormal cells in an area of the body. However, the number of abnormal cells is too small to form a tumour and may, therefore, be currently classed as benign. The World Health Organisation (WHO) system does not appear to recognise Stage 0 for NETs.
The most generic model for TNM staging is below but please note this could be adjusted for particular types of NET.
Primary Tumor (T) TX: Primary tumor cannot be evaluated T0: No evidence of primary tumour Tis: in situ (abnormal cells are present but have not spread to neighbouring tissue; although not cancer, in situ may become cancer and is sometimes called preinvasive cancer)
T1, T2, T3 and T4 is a measure of the size of, and/or invasion/penetration by, the primary tumour and the wording varies between different NET sites. e.g. for a small intestinal NET:
T1 tumour invades mucosa or submucosa and size <=1 cm
T2 tumour invades muscularis propria or size >1 cm
T3 tumour invades subserosa
T4 tumour invades the visceral peritoneum (serosa)/other organs
Distant Metastasis (M) MX: Distant metastasis cannot be evaluated M0: No distant metastasis M1: Distant metastasis is present
You may occasionally see TNM staging be prefixed by lower case letters. The most commonly used prefix is ‘p’ simply meaning the grading has been confirmed by pathology. e.g. pT4 N1 M1
Specialists can combine the Stage to create a TNM – for example:
This slide will be updated when I get access to WHO 2017 or updated AJCC pubication.
Summary
A complex area and I hope I have condensed it sufficiently for you to understand enough for your purposes. Despite looking very scientific, it is not an exact science. There are many variables as there always are with Neuroendocrine disease. NENs can be very challenging for a pathologist even an experienced one who may not have encountered NENs before. However, it is an extremely important part of initial diagnosis and also when needed during surveillance. It is a vital tool used by Multidisciplinary Teams (MDT) in treatment plans and for prognostic purposes. If you need to learn further, I recommend this document:
If you are interested in this subject and have one hour to spare, there is a great video here from LACNETS worth watching.
