VACCINE ASSOCIATED SARCOMAS IN CATS: AN UPDATE

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VACCINE ASSOCIATED SARCOMAS IN CATS: AN UPDATE

Postby GUEST » Fri Oct 03, 2003 6:19 pm

VACCINE ASSOCIATED SARCOMAS IN CATS: AN UPDATE

William S. Dernell, DVM, MS, Diplomate ACVS

Colorado State University, Fort Collins, Colorado

2001 ACVS Veterinary Symposium Small Animal Proceedings

Keywords:
Feline, Vaccine Associate Sarcomas, VAS



An association between soft tissue sarcoma formation and sites of vaccination was first recognized in the early 1990’s.(1) Since that time, recognition of this phenomenon has increased exponentially, exploding into a public and political disease issue. The true etiology or at least the relationship between vaccination (or other injection) and the formation of what are now called Vaccine Associated Sarcomas (VAS) remains unknown. Initial suspicions revolved around vaccine adjuvant materials, especially adjuvants containing metals (aluminum). Further investigation revealed VAS formation without adjuvant products and has raised the suspicion of metaplastic and neoplastic change secondary to an inflammatory reaction that appears to be unique to cats. Although vaccine reactions occur in dogs, they are less frequent and VAS formation has not been documented. Until the etiology and/or association can be elucidated, our attention needs to be focused on appropriate treatment, control or prevention.

The incidence of VAS is estimated to be somewhere between 1/1,000 to 1/10,000 cats vaccinated. Although feline leukemia vaccine and rabies have been most widely implicated, all feline vaccines and a number of non-vaccine injectable agents, generally repository type medications, have been associated with sarcoma formation. A suspicion of VAS is raised by the finding of any one or more of several pathologic criteria. These tumors are generally high grade (grade III if evaluated by the canine soft tissue sarcoma scheme) with substantial evidence of an inflammatory component. The inflammation most often consists of mononuclear cells, particularly macrophages. The finding of refractile material within the cytoplasm of inflammatory cells may represent metallic vaccine adjuvant and has been associated with VAS.


These tumors behave in a very aggressive manner, yet are generally confined to local tissue growth and invasion, rather than distant metastasis. The distant metastatic rate is estimated at 10-25%, and is often seen as a late event. This rate may actually increase as control of local tumor disease improves, allowing metastasis to occur. Local recurrence rates are high and are only partially related to the status of surgical margins. Although it is suspected that macroscopically or microscopically incomplete margins are associated with an increased rate of recurrence, recurrence rates seem to be higher than expected for cases in which a microscopically complete resection is obtained. Local recurrences in the face of clean margins (complete resection) are often referred to as ‘field recurrence’, ‘skip lesions’ or regional ‘metastases’. These terms refer to local re-growth that is not necessarily within the original surgical wound bed. Mechanistic theories for this include: induction of distant tissues through macrophages containing inductive material traveling through lymphatics; metaplastic induction secondary to the ‘regional’ inflammatory response; and true metastases of tumor cells through lymphatic or vascular channels. The latter theory is not as well supported owing to the fact that the distant metastatic rate is relatively low. Regardless of the mechanism, this biology requires that local therapy be aggressive or more appropriately, be regional in nature.

Cats are generally presented for a palpable mass in or near the injection site. The timing of VAS occurrence following vaccination is highly variable. The minimum time appears to be somewhere between 3 and 6 months following vaccination. The maximum time is not known, however, there have been reports of VAS occurring several years following vaccination in a particular site. Most masses evaluated prior to 3 months after vaccination are histologically consistent with granuloma. Because it appears that long-standing granulomas may be associated with VAS formation, it is recommended that any mass present for longer than 3 months undergo incisional or excisional biopsy. Care must be taken in planning the biopsy track for ease of subsequent removal at the time of definitive surgery. This is especially true for excisional biopsies since it is unlikely that this procedure will result in complete margins if the mass is diagnosed as a VAS. Although the metastatic potential of VAS is low (10-25%), staging with 3-view thoracic radiographs is still recommended. The finding of metastases is a negative prognostic indicator, yet it is possible that these lesions may progress slowly and local site treatment may still be warranted. Repeating the thoracic radiographs in 3-4 weeks will help to identify metastases with a slow doubling time which would be indicative of slow growth. Further staging involves evaluation of regional lymph nodes through palpation or imaging (ultrasound) followed by fine needle aspiration cytology of enlarged lymph nodes. Lymph node spread, however, is rare.1

The assessment of local disease extent and thus the surgical dose required for resection of larger, longer-standing lesions can be greatly aided by advanced imaging. The use of contrast-enhanced computed tomography (CT) has been shown to improve assessment of tissue plane invasion beyond what can be discerned by palpation, ultrasound or non-contrast CT. Due to the large inflammatory component to these tumors, CT may overestimate tissue involvement due to inflammatory changes within surrounding tissues. The use of CT images for radiation therapy computerized planning is very helpful in cases of VAS, especially larger, deeper masses, as involvement with multiple tissue planes within the radiation field is likely.2 Fields will often include dose-limiting tissues such as spinal cord. If radiation therapy is planned to follow surgery, computerized planning of radiation from CT images obtained after surgery is recommended, rather than from preoperative images, in order to better assess the position of tissue planes involved. Magnetic resonance (MR) imaging may be a very useful tool, in assessment of the degree of local disease, but it has yet to be evaluated for VAS.

Early local failure following treatment of VAS resulted in the institution of more aggressive surgical resections. The accepted standard for soft tissue sarcomas of 2-3 cm lateral margins and one additional tissue plane deep to what the tumor touches (Figure 1) will generally result in microscopically clean margins, yet an unacceptably high recurrence rate. The present recommendations are 3-5 cm laterally and 2 additional tissue planes deep to the discernible mass. Obtaining these resection margins may require partial scapulectomy, thoracic or abdominal wall resection or extremity amputation. In these cases, the decision to attempt surgical cure needs to be balanced against the potential for patient compromise. The overall (national) recurrence rate is estimated to be 50% at 1 year following surgery alone. This includes a wide array of margin distances. In one study, the institution of 5 cm lateral and 2 tissue plane deep margins has resulted in an improved local recurrence rate of less than 5% after a median of 6 months follow-up.3 Although this study is somewhat immature, it does hold promise of surgical cures with aggressive resection.


Figure 1. Schematic diagram of three-dimensional planning surrounding a malignant neoplasm. [From: Dernell WS, Withrow SJ. Preoperative patient planning and margin evaluation. Clin Techniques in Small Anim Pract. 1998;13(1):20.]



Due to lack of local tumor control early in the treatment of VAS, radiation has been implemented either as a primary treatment or in the adjuvant setting. Until the true efficacy of surgery alone (including radical resection) can be elucidated, the use of adjuvant radiation for the treatment of VAS is recommended. The advantage of radiation is that it allows regional therapy without compromise. Early reports of local disease control following radiation ranged from 50% with radiation alone to 75% with a combination of radiation and surgery. Earlier radiation protocols ranged from as low as 45 Gy to as high as 64 Gy in daily or every-other-day schemes. With experience, it has been shown that cats appear very tolerant to higher doses of radiation, especially in truncal areas where skin is the acutely responding tissue. Dogs show severe moist desquamation and often go through a period of intense pruritus. Cats, on the other hand, tend to show a dry desquamation that is associated with few clinical signs. This has allowed for protocols with increased total radiation dose, improving tumor control. Presently recommended protocols administer total doses in the low 60 Gy range. The use of electron therapy (as opposed to photon therapy) can be beneficial in that electrons are more superficially penetrating and will often spare deeper tissues from appreciable radiation doses. This is especially true for masses over the thorax, so that lung and heart can be spared, and over the spine to allow increased dose yet spare the spinal cord. Electron therapy requires a linear accelerator for administration. Increasing fractionation schemes (hyperfractionation) may also allow increased dose delivery with better sparing of normal tissues than coarse fractionation schemes.

Many institutions and practices advocate radiation therapy prior to surgery for VAS. The advantages of preoperative radiation are based on two main premises. The first is that surgery disturbs tissue planes through dissection as well as postoperative edema and hemorrhage, potentially increasing the field size, depth, and margins needed for effective treatment. Part of this concern stems from the radiation therapist being unaware of the boundaries of the surgical resection. Close association and communication between the surgeon and radiation therapist can decrease this concern. In addition, the placement of metallic clips (Hemoclips) at the boundaries (lateral as well as deep) of the dissection can aid in the treatment planning. The second concern is the induction of hypoxic regions within the surgical site. Hypoxic tissues and cells are resistant to radiation. This is a normal change following tissue disturbances, but can be decreased by gentle tissue handling, appropriate hemostasis and tension-free closure. If surgery is performed prior to radiation, preplanning the surgical excision is important, keeping these concerns in mind. In addition, less aggressive surgery may be indicated, to avoid detrimental changes, if radiation is planned postoperatively.

The primary disadvantage of performing surgery following radiation therapy is related to the tissue changes encountered. Irradiated tissues are compromised, especially in vascular supply. These tissues are slow to heal and less resistant to infection and tension. With this in mind, the surgeon also needs to have gentle tissue handling, appropriate hemostasis and strive for a tension-free closure. If it is possible to excise all the irradiated tissue and repair the defect with a vascularized graft, this may be preferred. The use of vascularized omental grafts may also greatly aid healing. Another concern regarding post-radiation surgery is the lack of discernable margins. If the tumor has decreased in size from the radiation, margin measurement becomes difficult. The recommendation at this point is to plan the margins based on the original tumor size and tissue involvement. This will require some method of documentation of the original tumor, either with skin markings, photographs or CT/MR images.

Although the rate of distant metastasis is low for VAS, combination treatment protocols including chemotherapy have been suggested and trials are being conducted using adjuvant chemotherapy. The reasons for chemotherapy are based on the theoretical increase in metastasis secondary to improved local disease control as well as the potential benefit in local disease control. In studies conducted thus far, improvement in survival has been small, yet present using doxorubicin either at the same time as radiation therapy or beginning after recovery (approximately one month following radiation therapy). The impact of chemotherapy may be diluted due to case selection bias in choosing chemotherapy for more advanced disease or high-risk patients. Further studies may help to elucidate the true efficacy of adjuvant chemotherapy.4


Follow-up for VAS cases must focus on local disease control. Most failures are within the treatment site and most will occur within 6-9 months of the completion of therapy. Diligent palpation by the owner is the cornerstone, with further evaluation of suspicious changes by the veterinarian. Masses which show progressive growth should undergo biopsy. The need for periodic staging measures is unknown, but they are likely indicated prior to further major interventions for recurrent disease. The options for recurrent disease are dependent on prior treatment. Re-irradiation has not been evaluated, but is likely to result in unacceptable normal tissue complications due to the high doses used in primary therapy. Radiation could be considered for new growth outside of the original treatment field. Surgical removal may be an option for recurrence, the surgical dose being dependent on prior surgery, local tissue involvement and the impact of irradiated tissues. Following aggressive first-line therapy, options for recurrent disease may be limited to palliative surgical resection of the mass.

Due to the many concerns surrounding VAS, the AVMA formed the Vaccine Associated Sarcoma Task Force (VASTF). This task force is charged with assessing the impact of this disease, the responsibilities of owners, veterinarians and vaccine manufacturers, establishing research directions and funding as well as making recommendations for treatment and prevention. A number of clinical and bench research projects have been sponsored by the VASTF, through funding from vaccine manufacturers and veterinary associations, in the areas of incidence and impact, etiology, prevention and treatment. Recommendations of disease prevention and treatment have also been made through the American Association of Feline Practitioners and pamphlets are available. In summary, these organizations recommend avoiding overvaccination and aggressive diagnostics for injection site reactions as well as aggressive treatment strategies. Vaccine site recommendations have been variable, but attempts been made to improve treatment options, especially surgical control. The details of all of these recommendations are evolving as more is learned about the disease and treatment response. In addition, adverse reactions to injectable agents should be reported through the Veterinary Practitioners Reporting Program of the US Pharmacopeia.

References

Hendrick MJ: Feline vaccine associated sarcomas. Cancer Invest 1999;17:273-277.
McEntee MC, Samii VF, Madewell BR: Contrast-enhanced computed tomography for treatment planning of feline vaccine-associated sarcomas; preliminary findings. Proc Vet Cancer Soc 1999;62 (abstract).
Kuntz CA, Powers BE. Modified wide local excision for vaccine associated sarcomas in cats. Vet Surg 2000;29:481 (abstract).
Poirier VJ, Kurzmann ID, Vail DM. The role of chemotherapy in vaccine associated sarcoma: Doxil versus doxorubicin. Proc Vet Cancer Soc 2000;43 (abstract).
GUEST
 

vas 2004 update

Postby guest » Thu Mar 11, 2004 10:56 am

Update on Feline Fibrosarcoma
Patrick Devauchelle, DVM


The GREFFI (Groupe d'Etudes des Fibrosarcomes Félins) was founded following the controversy relating to the development of feline vaccine-associated fibrosarcomas, in order to provide rational aetiological information. GREFFI activities, within a wider perspective, have been oriented towards pathogenesis, diagnosis improvement, and design of suitable therapeutic protocols. Faced with such a complex issue, the GREFFI has adopted a multidisciplinary and global approach, involving veterinary practitioners in targeted investigations. They have also established collaborative relationships with the North American VAFSF (Vaccine Associated Feline Sarcoma Task Force) dealing with the same topic.

Origin of "Feline Fibrosarcoma Complex"

Before the 1990s, sarcomas with fusiform cells with cutaneous or subcutaneous locations were known to be rare in cats. They now form part of the most common, if not the most frequent tumors in cats both in France and abroad since, according to investigations, they amount to 12-41% of all feline cutaneous tumors. Frequency estimations in Northern America have reported 20 cases out of 100,000 cats. In Europe, a retrospective investigation covering a period of 5 years reported 0.4 pharmacovigilance cases out of 100,000 cats under care. In France, the mean age of cats developing a fibrosarcoma is 9.6 years within a large interval of 3.2-16 years (95% confidence interval), which is little typical of spontaneous tumors. Distribution seems to have evolved from a single peak at 10-12 years towards bimodal distribution with a first peak at 6-7 years and a second at 10-11 years. Moreover, tumors are significantly more often located at classical injections sites on cats.

In Northern America, epidemiological data have served as a basis for the assumption made by Hendrik and then by other authors, according to which vaccine injections would increase the relative risk of fibrosarcoma development. Other elements support this assumption:

Clinical findings: presence of focal granulomatous panniculitis of post-vaccinal type,

Anatomopathological findings: morphological differences between fibrosarcomas at the site of injection and presence of aluminium hydroxide (constituent of numerous oil-adjuvanted vaccines) in the macrophages infiltrating fibrosarcomas.

In addition, carcinogenesis related to chronic inflammatory phenomena has already been described in another context i.e., chemo- or radio-induced tumors, oesophageal osteosarcoma caused by Spirocerca lupi infestation, appendicular osteosarcoma in the presence of osteosynthesis material, and spinocellular epithelioma of the white cat.

The assumption of vaccine injection-associated tumors is likely; however, it is impossible to determine whether they are attributable to the injection of irritating or allergenic substances all the less so since therapeutic injections of slow release products have also been incriminated. More precisely, the iatrogenic cause appears quite likely but it is not currently possible to define the original substance.

The determination of carcinogenesis is complex and it has not yet been possible to establish a pathogenic pattern. Pathogenesis is even more complex since, in this particular case, the simplest assumptions of FeLV, FeSV, papillomavirus and polyomavirus induction have been excluded. In such a context, further investigations dealing with protooncogens (e.g., c-myc, c-jun) and measurement of free radicals in the microenvironment would be necessary.

Clinical presentation

Classically, feline fibrosarcoma develops in the form of firm, nodular or multinodular cutaneous lesions, which are neither painful nor ulcerated. Tumors are preferentially located at the injection site:

Interscapular area, dorsal side of the neck: 40-49.5%,

Thorax, flanks: 25-29%,

Loins and back: 13-14%.

Tumors at limb extremities, as they used to be described, have now become rare. FeSV-induced fibrosarcomas, systematically multicentric, are quite rare, too, and mainly affect young kittens.

Feline fibrosarcomas are located subcutaneously and therefore rarely ulcerated, except during the terminal stage. They are rarely painful except when they are very large or infiltrated with deep structures.

The speed of evolution of fibrosarcomas is greatly variable. Small-size nodules may persist as such for quite a long time; inversely, other nodules may double in size within a very short period, which would show that tumoral growth accelerates alongside consecutive excisions.

Microscopic data

Although lesions have the same appearance from a macroscopic viewpoint, conventional microscopic examinations show that feline fibrosarcomas are heterogeneous. Their common characteristic is the presence of neoplasic fusiform cells, hence providing evidence of their mesenchymatous origin, but whose differentiation may vary (fibroblasts, osteoblasts, chondroblasts, etc.).

Up until lately, the know classification of feline fibrosarcomas was based on three major histological types:

Purely tumoral type, including sensu stricto fibrosarcomas that represent 30% of the tumors observed. They contain dense so called 'fishbone-shaped" fusiform cells within a collagenic stroma. Mitoses are numerous, and necrotic or haemorrhagic foci are not unusual.

Malignant fibrohistiocytomas, representing 60% of the tumors observed. These tumors are polymorphous and behave like tumoral cells of mesenchymatous appearance, associated with other tumoral cells of histiocytic appearance, all of which contained in a fairly abundant collagenic stroma. Osseous metaplasias, giant multinucleated cells, or myxoid stroma form part of their polymorphism.

Sarcomas (osteosarcomas, chondrosarcomas, hemangiosarcomas, rhabdomysosarcomas, neurofibrosarcomas, etc.) are sometimes associated with the feline fibrosarcoma complex.

Fibromastoses, whose incidence is much lower. They are characterized by a highly differentiated fibroblastic tumoral proliferation, associated with dense collagenic stroma.

The mitotic index is low. Examination of fasciae located close to the lesion often reveals the presence of infraclinical tumoral foci, which may explain post-surgical relapses observed with this type of tumors.

Granulomatous panniculitis are a specific entity since they are not tumoral but inflammatory with the infiltrated necrotic central area surrounded with mononucleated cells often associated with polynucleated neutrophils and eosinophils. This phenomenon could correspond to the materialization of a specific sensitivity of the subcutaneous tissue of cats in which it develops. It could therefore be the source of a future fibrosarcoma. However, the correlation between this inflammatory lesion and fibrosarcoma tumoral lesions has not been established yet.

Data recently obtained by the GREFFI and based on immunohistochemical procedures however question the above classification. More precisely, two elements of observation disturb the differentiation between fibrosarcoma and malignant fibrohistiosarcoma:

According to conventional histology, sensu stricto fibrosarcomas are tumors with fusiform cells that do not contain any other type of cells. In fact, all fibrosarcomas prove to contain a variable quantity of macrophagic cells when the latter are labelled with suitable antibodies.

According to conventional histology, both malignant fibrohistiosarcomas and fibrosarcomas contain enough macrophagic cells to be visible. These macrophages are not tumoral but merely consist of reactional stromal cells.

Overall, the nature of both types of lesions mentioned above is identical, except for the quantity of cells of stromal macrophagic origin which is the only way to differentiate them.

Biological behaviour

There are two major types of tumoral behaviour:

Tumors with local (relapse) and systemic (metastasis) aggressivity.
They consist of fibrosarcomas (sensu stricto fibrosarcoma and malignant fibrohistiocytoma) and related sarcomas with significant local aggressivity and presenting a serious risk of post-surgical relapses. Metastasic capacity is low (10-15% approximately). Metastases are located in lymph nodes and the lungs, and usually develop quite a long time following onset of the initial tumor.

Lesions with local aggressivity (relapse) only.
They consist of fibromatoses which do not metastize but frequently relapse or develop at another site. Relapses are related to peripheral and infraclinical tumoral foci which are difficult to remove, even during wide surgical excision.

Granulomatous panniculitis develops within a few weeks following an inflammatory stimulus, whichever it is (e.g., injection of vaccine, slow release antibiotics, or injectable antiflea preparations, etc.). However, the detection of panniculitis presents a double advantage:

Revealing the sensitivity of subcutaneous connective tissue in some cats during a chemical or physical aggression,

Their specific evolution would explain the evolution of granulomatous panniculitis to fibrosarcoma.

Treatment of feline fibrosarcoma

For most the above tumors, the therapeutic procedure to be implemented to treat feline fibrosarcomas is complex. The presumed biological behaviour of each tumor and of each individual must be taken into account.

The therapeutic strategy is based on wide surgical excision, whether associated or not with other local (radiotherapy) or general (chemotherapy) treatments. The surgery of tumors with serious local aggressivity must be associated with a complementary treatment so as to reduce local relapses, which is the role of radiotherapy. Chemotherapy aims at limiting the development of distant metastases. Immonogenotherapy is currently used experimentally, but the preliminary results obtained lead us to believe that it will develop rapidly.

Surgery

Like most tumors, surgery remains the main treatment for feline fibrosarcomas. Both the precocity and the extent of excision are conditions for the success of surgery. In effect, if the operation is carried out when the tumor has already reach quite a large size, excision is difficult to perform and, therefore, probably incomplete. The best results are obtained with tumors smaller than 1cm3: any subcutaneous neoformation must be excised and analysed in the shortest possible time.

In addition, aggressive surgery is largely responsible for the frequency of local relapses since fibrosarcomas are conjunctival tumors and, therefore, encapsulated and frequently infiltrated in muscles and adjacent fascia. It is advisable to remove the whole muscle of fascia in whose contact the tumor has developed (external oblique muscle and fascia in case of abdominal localization, cutaneous muscle in the case of thoracic localization, etc.) and even remove all adjacent muscles, where possible. In the event of interscapular fibrosarcoma, it is sometimes necessary to perform a scapulectomy together with the excision of spinous processes which often are the seat of local relapses.

With a view to reducing the risk of carcinogenesis induced by post-surgical inflammation, reconstruction will be minimal and non-inflammatory stitching material shall be used (in particular, catgut must not be used).

Radiotherapy

Complementary radiotherapy to surgery is particularly suited for tumors with a potentially high risk of local relapses. Sensu stricto fibrosarcomas, malignant fibrohistiocytomas, and all soft tissue sarcomas with a high mitotic index are good indications for adjuvant radiotherapy. On the other hand, radiotherapy is not a good indication for fibromatoses and sarcomas.

Interstitial radiotherapy or curietherapy allow addressing many of the problems posed by the feline fibrosarcoma.

There are so many parameters involved in the objective evaluation of adjuvant curietherapy that they are difficult to control. Practically speaking, we have observed that the efficiency of adjuvant curietherapy on feline fibrosarcomas depends on several factors:

Tumor size before excision. The tumor size conditions the quality of excision, which is the reason why the curietherapy of large-sized tumors achieves poorer results;

Histological nature of the tumor. Fibrohistiocytomas, sensu stricto fibrosarcomas, and sarcomas with high mitotic index are more radiosensitive than fibromatoses or low-grade fibrosarcomas.

Number of previous excisions. Radiotherapy following a first excision is much more efficient than if the tumor has already relapsed several times.

Extent and quality of surgical excision. The lesser tumoral cells on the excision site, the greater the efficiency of adjuvant radiotherapy.

Early radiotherapy following surgery. The surgical excision region must be radiated as soon as skin cicatrisation is sufficient (usually 1-2 weeks following surgery) and not when the tumor has started relapsing.

Precise localization of the area to be radiated. The radiotherapist must accurately locate the initial tumor in order to determine the area to be radiated. This requires the surgeon to draw precise diagrams or even use pictures.

As a conclusion, the best long-term results can be obtained during adjuvant curietherapy of small-sized tumors (less than 1 cm in diameter) with high mitotic index removed for the first time. Excision must be wide and curietherapy carried out within three weeks following excision.

Chemotherapy

Feline fibrosarcoma tumors do not metastize greatly (less than 15%), usually quite late and often when satisfactory local examination has been obtained with adjuvant radiotherapy. Moreover, soft tissue sarcomas are considered chemosensitive in both human and veterinary medicine. The advantage of chemotherapy therefore is disputable for such tumors.

Immunotherapy

Non-specific immunomodulators, which were widely used twenty years ago, have been abandoned in veterinary medicine due to their low efficiency and little specificity. In the United States, only Acenaman® - an Aloe vera extract with immunomodulating properties-has been authorized for marketing for the treatment of numerous solid tumors. The benefit of its use however remains debatable.

In human medicine, the use of cytokines, such as interleukine2 or gamma interferon, are particularly promising but their systemic toxicity makes them delicate to use. This toxicity problem has been solved thanks to the use of genetically modified cytokine producing cells.

Clinical trials were carried out on cats having developed a fibrosarcoma. VERO cells (monkey kidney cell line) that were genetically modified in order to produce interleukine2 (hIL2), were used. When injected into the surgical excision site, the VERO-hIL2 cells behaved as "micropumps" producing human interleukine2. The interleukine2 released is active and stimulates the multiplication of immunocompetent cells on the tumoral site. A number of these cells are specifically directed against the tumoral antigens carried by the operated tumor. This investigation gave evidence of a statistically significant improvement of relapse-free survival and even global survival of the cats subjected to surgery, curietherapy and VERO-hIL2 cells, as opposed to those cats that were only subjected to surgery and curietherapy. This treatment is therefore a promising procedure for the treatment of tumors in both man and the animal. Several protocols are currently implemented with a view to further improving the results obtained.

CONCLUSION

The prognosis of such tumors continues to be poor although the therapeutic arsenal available allows intervening relatively efficiently. Early and wide excision completed with an adjuvant treatment (curietherapy or immunotherapy) improves the prognosis. Lastly, diagnostic improvement using immunochemical procedures would allow intervening in the best suited manner therapeutically.

Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker)
Patrick Devauchelle, DVM
France


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