Veterinary Society of
Surgical Oncology

GENERAL CONSIDERATIONS

Biologic Behaviour

General Considerations

  • uncommon and accounts for 4%-9% of all feline cancers
  • intestinal tumors (small and large) account for 68%-94% of all non-oral GI tumors
  • small intestinal tumors are more common
  • Lymphosarcoma

  • intestinal LSA is most common intestinal tumor in cats
  • mean age 10-12 years (range, 1-18 years)
  • breed predisposition: none
  • role of FeLV and FIV uncertain as majority of cats with alimentary LSA are FeLV negative using serology and immunoflourescence assay, but many are positive using polymerase chain reaction
  • replication defective, latent or low level or intermittent shedding are not detectable using traditional detection methods and may be involved in the etiopathogenesis of feline alimentary LSA
  • proportion of T and B cell LSA varies with some reporting predominance of B cell immunophenotype, T cell immunophenotype, and equal distribution
  • feline alimentary LSA is usually either:
  • stage II: 32%, single resectable site ± mesenteric lymph node involvement
  • stage III: 43%, single non-resectable site or extranodal secondary site
  • Adenocarcinoma

  • intestinal ADC accounts for 20%-35% of all feline GI tumors
  • mean age 11 years (range, 2-17 years)
  • breed predisposition: Siamese
  • intestinal ADC has no association with FeLV or FIV
  • sites: small intestine and particularly jejunum or ileum
  • histologic subtypes: tubular, undifferentiated, and mucinous
  • tubular ADC may have a better survival rate than undifferentiated and mucinous ADC
  • majority of feline intestinal ADC are advanced with 72% metastatic rate at diagnosis
  • metastatic sites: peritoneum and regional lymph node are common, but others include liver, bone, and lungs
  • Duodenal Adenomatous Polyp

  • mean age 12 years (range, 6-18 years)
  • sex predilection: 83% male castrated
  • Globule Leukocyte Tumor

  • characterized by large mononuclear cells with prominent azurophilic granules (= large, homogenous, peroxidase-positive granules of progranulocytes and early myelocytes that stain blue due to acid mucopolysaccharide content)
  • diffuse metastasis at diagnosis is common
  • Mast Cell Tumor

  • intestinal MCT is the 3rd most common feline GI tumor (after LSA and ADC)
  • mean age 13 years
  • histology: less differentiated with less prominent cytoplasmic granules
  • more commonly involves small intestine with equal distribution between duodenum, jejunum, and ileum
  • < 15% colonic involvement
  • peritoneal effusion is relatively common but peripheral mastocytosis and eosinophilia is rare
  • intestinal MCT is not associated with mucosal ulceration
  • metastasis is common and sites include mesenteric lymph nodes and liver ± spleen, lung, and bone marrow
  • Other Intestinal Tumors

  • leiomyoma and leiomyosarcoma are rare
  • intestinal HSA has been reported in 4 cats, including 1 involving the small intestine
  • carcinoids are rare
  • Clinical Signs

  • anorexia, weight loss, and intermittent vomiting
  • acute and chronic vomiting with hematemesis in cats with duodenal adenomatous polyps
  • Diagnosis

    Physical Examination

  • palpable abdominal mass and cachexia are common
  • other findings include dehydration and abdominal pain
  • Laboratory Tests

  • mild to moderate anemia common with intestinal LSA (43%) and ADC
  • leukocytosis and neutrophilia ± lymphopenia
  • paraneoplastic leukocytosis may be caused by production by either G-CSF or GM-CSF
  • 50% cats with intestinal tumors (mostly ADC) have hyperglycemia and 85% have elevated ALP
  • other biochemistry abnormalities include mild hypokalemia, azotemia, and hypoproteinemia
  • hypercalcemia reported in 1 cat with intestinal LSA
  • moderate to marked anemia, azotemia, and elevated liver enzymes reported in cats with duodenal polyps
  • Abdominal Radiography

  • abdominal mass frequently identified with feline intestinal LSA
  • abdominal mass, bowel obstruction ± ascites identified in 21%-50% of cats with intestinal ADC
  • Contrast Radiography

  • non-lymphoid intestinal mass and duodenal polyps are identified in 75% and 83% of cats, respectively
  • survey radiographs may be sufficient to proceed with exploratory surgery without contrast studies
  • contrast radiographs: mural lesions include luminal filling defect, intestinal wall thickening, mucosal ulceration, abnormal positioning of intestinal loops, and constricting annular lesions
  • From: Slatter DH (ed): Textbook of Small Animal Surgery (3rd ed).

    Ultrasonography

  • transmural thickening, loss of normal intestinal layering, localized masses, mesenteric lymphadenopathy, and peritoneal effusion are common findings with intestinal LSA ± hepatomegaly
  • circumferential transmural thickening with loss of normal intestinal layering has been reported in 5 cats with intestinal ADC
  • Endoscopy

  • endoscopy has been used successfully to identify duodenal polyps
  • Exploratory Celiotomy

  • definitive diagnosis with exploratory celiotomy and biopsy
  • feline ADC has gross appearance of annular scar-like constriction with variable degree of post-stenotic dilatation
  • duodenal polyps are palpable and usually within 1 cm of the pylorus
  • leiomyomas and sarcomas are usually large solitary masses growing through the intestinal serosa
  • Treatment

    Surgery

  • debilitation and hypoproteinemia may complicate treatment
  • exploratory celiotomy with resection and end-to-end anastomosis with 4-8 cm margins and serosal patching of anastomosis
  • mesenteric and regional lymph nodes should be assessed ± aspirated
  • Chemotherapy

  • multiagent protocols recommended for LSA as either adjuvant therapy or sole treatment for diffuse disease
  • chemotherapy is also recommended for cats with intestinal plasmacytoma and MCT
  • no effective chemotherapy for ADC
  • multiagent chemotherapy (L-asparaginase, prednisone, cyclophosphamide and vincristine) used in a cat with unresectable and diffuse globule leukocyte tumor with PR
  • Prognosis

    Lymphosarcoma

  • MST 201-280 days with a variety of different chemotherapy protocols
  • 60%-87% overall response rate with median response duration 120 days
  • MST 11 months for cats with epitheliotropic intestinal LSA
  • survival times were dependent on response to chemotherapy:
  • survival times in cats refractory to chemotherapy were < 3.5 months
  • survival times in cats responsive to chemotherapy were > 11 months
  • Adenocarcinoma

  • 50% local tumor recurrence rate in long-term survivors
  • MST 5-15 months for surgery alone surgery
  • survival time may be influenced by metastatic disease and histologic subtype
  • mean survival time in cats with lymph node metastasis is 12 months v 15 months overall
  • furthermore, 2 cats with omental carcinomatosis lived 4.5 months and 28 months after surgery
  • mean survival time in cats with tubular ADC is 11 months v 4 months undifferentiated and mucinous ADC
  • Mast Cell Tumor

  • poor prognosis as most cats die or euthanased soon after diagnosis
  • solitary intestinal MCT without metastasis may have prolonged survival following end-to-end anastomosis
  • Duodenal Polyp

  • surgical resection and end-to-end anastomosis can be curative
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    SMALL INTESTINAL TUMORS

       
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