Conference Vancouver, B.C. June 11, 2001
Speakers
Dr Sutcliffe: I would like to go to Head and Neck cancer, Helen you will have to help me I didn’t quite get them down as quickly, it seem to me that cervical neck nodes, with suspected carcinoma of unknown primary, you are putting forward as a recommendation for PET studies… Sorry, the appropriateness of that recommendation? I believe in the initial staging of disease you did not believe that PET should be recommended.
Dr Anderson: I said with selected patients where it could potentially affect treatment planning there was a role for that—selected patients.
Dr Sutcliffe: So it is a highly individualized type of recommendation? OK, and the diagnosis of suspected recurrence after 3 months of radiation.
Dr Anderson: Yes, I thought there was a role for the detection of recurrent disease. In a situation where there is some doubt as to whether it is post surgical scarring or post radiation changes and perhaps disease is expected there definitely is a role.
Dr Sutcliffe: Comments on that either from the floor or from our expert panel? Would you accept those indications; would you say there are some that are not there that you believe to be important?
Dr Conti: I think the one area that I believe is significant is the patient that presents with advanced disease and you are still considering radical neck resection. It is that group of patients, there is a very high incidence of conjulateral disease and it can have a direct impact on quality of life, morbidity for the patient, it may not affect outcome in the end, but I think it is up to 30% of conjulateral disease that it is undetected by anatomical imaging in that group.
Dr Wahl: And I might also comment that certainly Peter Valk has described this and we certainly have seen this anecdotally when you see the patients with more advanced primary disease can uncommonly have disseminated disease, not uncommon thoracic metastasis which would preclude the radical neck surgery so maybe that would be one of the groups you might consider doing selected studies pre-surgically but I would also do more than just the neck. I would certainly do the whole body study. With evidence at least anecdotally being most for thoracic and upper mediastinum … of abnormalities.
Dr Baum: Also and not forgetting the secondary tumours, which are present in up to 15 to 20% of these patients like esophageal and chin cancer and lung cancer I mean the toxic substances are the same.
Floor: I think the discussion on Head and Neck cancer needs to be a little less generic in the case of nasopharyngeal cancer which is a disease that obviously is much more common in Asia and other parts of the world, we also see a lot of it in Vancouver, where the incidence of metastatic disease at presentation is very much higher. Maybe, I haven’t heard it mentioned, it is I think quite a distinct entity and different both epidemiologically and pathologically than Head and Neck cancer due to alcohol and tobacco use.
Dr Sutcliffe: Any comments from the panel with respect to distinguishing nasopharyngeal as a specific consideration?
Dr Conti: We have studied a number of cases like that, you are absolutely correct when you see really frequently metastatic disease beyond the head and neck region in that population—and it goes back to the comment I made earlier. That if you ask the question whether there is metastatic disease you need to use the test that best demonstrates the metastatic disease if you are going to act on the results. So in this particular case once again you have a choice perhaps between say CT and PET, I think that PET has a distinct advantage as you have heard throughout the day.
Floor: I just wanted make a general comment, it seems to me that in the discussion for the lymph node we do see that when you use the definitive gold standard of biopsy that in fact often it is actually low and the problem is in a lot of the studies where you are looking at higher stage disease, metastatic disease, that in fact the gold standard, I am not quite sure what was in these studies. So the sensitivities and specificities that you are quoting that you are suddenly going to apply to a group of patients, primarily staged in which you plan to substitute this wonderful test isn’t clear to me that those are the numbers that you would chose to use, so that I am not sure that you can take information that is being applied by sequential layering of a multitude of tests to suddenly say that this one test is going to be the definitive metastatic search is actually fair or correct and that I think that it does beg determining the true incidence of the true specificity and sensitivity in a completely different setting, than some of these tests studies that have been quoted so the gold standard has been really unclear for some of these that we have been discussing?
Dr Shreve: If I could just comment, obviously the gold standard is tissue, if you can get it and even tissue gold standard isn’t always 100% because there can be sampling errors in biopsies. This is a problem with many of these studies is what is the gold standard in determining sensitivity and specificity and we have struggled with that over the years because in many instances every single metastasis is not actually proven so if you count lesions usually you don’t have tissue proof of all the lesions but the theme we keep coming back to is, if you ask the question: is there metastatic disease and you want to do an imaging test. Then the question is which imaging test is most accurate for metastatic disease and there is a preponderance of evidence that that is PET.
Now typically when we find a distant lesion we will get tissue proof and I think it has also been reiterated here that in the neck and mediastinum, you really need to prove by tissue diagnosis if you can, whether something is indeed a positive node because of the false positive rate due to inflammation but it is not that we completely substitute PET for tissue diagnosis. We use PET to direct us to most efficaciously to the correct tissue diagnosis and relative to CT, PET has clear cut advantages in most of these neoplasms.
Floor: I just want to go back to colorectal, for a minute, the one recommendation that it be used in patients who are asymptomatic but have an elevation of their tumour marker there have been a number of studies published showing that there isn’t any really definite benefit to following patients with tumour markers and it was my understanding that we are trying to educate the mostly community physicians to stop ordering CEAs, stop ordering CA15.3s, 19-9s in patients who have been treated for their disease. So I am just wondering how that recommendation ties in with that because I mean I certainly have been in that situation before where I have had consults coming in from family doctors that someone who had a breast cancer or colon cancer resected a few years ago and now their marker is going up and they end up with a million dollar work up and you don’t find anything.
Dr Baum: I think that one of the main reasons to doubt about the usefulness of tumour markers was the lead time of tumour markers because conventional imaging was not able to find and localize the tumour. Now I think this has exactly changed by application of FDG-PET at least in colorectal cancer, in our series and this involved several hundred patients there was if I remember only two patients with an elevated CEA where the PET scan was negative and this turned out to be brain metastasis of colorectal cancer which is quite rare, but where we missed it, but all the others had positive lesions so in my view it is very important to do tumour markers in the follow up of high risk patients especially Dukes C and so on, and to detect early disease especially single liver metastasis, which can be resected or single lung metastasis which can be seen and resected.