Soft tissue sarcomas

Now we’ll first talk about the soft tissue sarcomas, and these are usually solitary, painless and palpable. The majority occur in the extremities. In the lower extremity, 40% of these are the highest amount and 75% of these are above the knee. They can also occur in the trunk where the most common area is the retroperitoneum, and then also rarely in the head and neck area. In terms of sites and histologies, usually in the extremity its MFH, synovial, lipo and fibro and most of these patients develop lung mets. The tumor usually avoids the liver. In the retroperitoneal area, lipos, leiomyosarcomas, there’s intraabdominal spread as well as liver and lung mets. In the chest wall, desmoid, lipo, leiomyo. The GI tract, leiomyosarcomas and then the newer-named GI stromal and GI autonomic tumors, which are extremely resistant to chemotherapy. In the GU tract, leiomyos and mesodermal mixed. Now what’s extremely important when you first see these patients, especially if this is an extremity sarcoma, is that you obtain the tissue in the right format. It’s really recommended that if possible you refer these patients to surgeons who have experience in doing the ultimate procedure. Really, if you are going to do a biopsy, you want to do an incisional biopsy, not an excisional biopsy unless it’s a very small lesion. And you want to make sure that the plane of that dissection is longitudinal to the muscle and not perpendicular. If you have the facilities, probably now at most major centers the majority of biopsies are done as a core true cut. I would say at our center about 95%, 98% of our biopsies are done by our radiologists. The advantage to that is that under CT guidance they can hit different areas of the tumor, because sometimes some of these tumors have necrotic areas and you may get no tissue or you may get a low grade tissue in one area and a high grade in another.

This is a study, an old study. There have been two other studies more recently. One from our institution, one from Memorial, looking at the value of core and needle biopsy compared to FNA. And you can see there is a much higher sensitivity, specificity and accuracy. Really it’s recommended to get at least three core and needle samples. We usually only use FNA’s to confirm a recurrence. Because it’s real important not only to determine, if possible, the exact histopathology of the sarcoma, but also to determine the grade. What’s critically important also is that you have a pathologist who has some experience in reading these and has some familiarity with the different immunohistochemical stains. You need to be aware that for some of these, in terms of helping delineating the type of sarcoma you are dealing with; angiosarcomas having CD34 factor 8; leiomyosarcomas having desmoid muscle-specific and smooth muscle actin; Ewings sarcoma having HB71013. None of these are absolutely specific but they can be very helpful in delineating the type of sarcoma you are dealing with. In addition, more recently now, there have been several different fusion genes based on different translocations that have occurred for some of these sarcomas, that are fairly diagnostic. One of them being the translocation of 11-22 for Ewings or primitive neurectodermal tumors. Also for synovial sarcoma, a translocation of X and 18. Looking at SID and SS-1 and SX-2 and we have found now that not only can these be somewhat diagnostic for diagnosing the sarcoma, but in this instance with synovial sarcoma it can tell whether you are dealing with a biphasic or a monophasic tumor. The biphasic being SS-1, the monophasic being SX-2 And not only is it helpful in delineating that but also in prognosis. The monophasic tumor being all spindle cell, having a much better prognosis than a biphasic tumor where there is an epithelial component as well.

Now what do we do in terms of a work-up? Well, first of all we want to find the local extent of the tumor and probably the best test for extremity, trunk and head and neck is an MRI. But in addition to that, if it’s in the retroperitoneal area or an intraabdominal sarcoma, we want to get a CT because we want to look at the abdominal contents and also evaluate the liver where the tumor can metastasize to. Then in addition, for all these sites, they have the potential to metastasize to the lung. So we want to get a chest CT as well. Now there are several major prognostic factors. Histologic rate is extremely important. Low grade tumors tend to stay locally, tend not to metastasize, tend to have a much better prognosis. We need to know the extent and location of surgical margins and those should be delineated by the surgeon. We want, if possible, to get margins of at least 1-2 cm. That is not always possible, depending where the tumor is. It’s much harder if it’s in the retroperitoneal area, much easier in the extremity area. Size becomes important. Those tumors greater than 5 cm and even greater than 10 cm are much more likely to recur and have a worse prognosis. The primary site becomes important. Distal tumors usually do better than proximal tumors, they are picked up earlier, usually easier to resect. Those tumors that are subcutaneous usually do better than deep. Those tumors that are intra-compartmental usually do better than extra-compartmental. Those tumors that are in the extremities usually do better than the trunk, and head and neck usually do better than the retroperitoneum. Retroperitoneum tumors are usually picked up late because they are usually very big, the patient doesn’t have any symptoms, then once they are picked up they are usually very near vital structures and it’s very hard to do an adequate full resection to remove all the tumor. In fact, for most patients who are at major centers getting surgery for retroperitoneal tumor, approximately 75% of the time a vital organ or part of a vital organ has to be removed in addition to the sarcoma.

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