Lecture 15 3/24/25 Flashcards
What are the most common GI tumors in dogs?
-primary GI lymphoma
-adenocarcinoma
-leiomyosarcoma and GIST
What are the general characteristics of primary GI lymphoma in dogs?
-treated with CHOP chemo protocol
-poor prognosis
What are the general characteristics of adenocarcinoma in dogs?
-most common in the large intestine and rectum
-high metastatic potential
-metastasizes to LNs, lungs, and peritoneum
Why are leiomyosarcoma and GIST grouped together?
the histopathology of these two diseases looks identical and they can only be differentiated via immunohistochemistry
Which tissue is affected by leiomyosarcoma?
smooth muscle
What are the characteristics of GIST?
-affects interstitial cells of Cajal
-most commonly found in cecum
-commonly misclassified as leiomyosarcoma
-C-kit mutation present in nearly all cases
Why is it important to differentiate leiomyosarcoma from GIST?
there are treatment options that vary based on the tumor type
Where do leiomyosarcoma and GIST metastasize to?
-LNs
-liver
-mesentery
What are the most common GI tumors in cats?
-lymphoma
-adenocarcinoma
-mast cell tumor
What are the general characteristics of adenocarcinoma in cats?
-more common in small intestine than colon
-high metastatic potential
What are the general characteristics of mast cell tumors in cats?
-GI tract is the most aggressive location for MCT
-high metastatic potential
How are GI cancers diagnosed and staged?
-abdominal ultrasound plus FNA cytology
-exploratory laparotomy with histopath.
-minimum database
-thoracic rads
When is surgery used as a treatment for GI cancer?
-cancers other than LSA
-no evidence of metastatic disease on staging
When is chemotherapy used as a treatment for GI cancer?
GIST with metastasis
What are the characteristics of GI cancer prognosis?
-prognosis is variable
-best prognosis for canine leiomyosarcoma/GIST with no metastasis and feline small cell GI LSA
What are the four types of hepatobiliary tumors?
-hepatocellular (adenoma and carcinoma)
-bile duct (adenoma and carcinoma)
-mesenchymal (leiomyosarcoma, hemangiosarcoma, fibrosarcoma)
-neuroendocrine
Which hepatobiliary tumor is most common in dogs?
hepatocellular carcinoma
What are the possible distributions of hepatocellular carcinoma in dogs?
-massive
-nodular
-diffuse
Which hepatobiliary tumor most common in cats?
biliary cystadenoma (benign)
What are the clinical signs of hepatobiliary tumors?
-may be asymptomatic
-lethargy
-anorexia
-weight loss
-vomiting
-icterus
-palpable mass(es)
How are hepatobiliary tumors diagnosed?
-abdominal ultrasound
-guided FNA
-biopsy and histopath.
-check clotting times prior to surgery
Why is guided FNA not typically diagnostic for hepatocellular carcinoma?
HCC is often well-differentiated and difficult to distinguish from adenoma
What finding is seen on CBC in hepatobiliary tumors?
anemia
What findings are seen on chem/lytes in hepatobiliary tumors?
-increased liver enzymes
-abnormal liver function parameters/GUAC
-paraneoplastic hypoglycemia
Which imaging modalities are used to stage hepatobiliary tumors?
-thoracic rads
-CT of abdomen +/- thorax
What are the characteristics of surgery as a treatment of hepatobiliary tumors?
-best if tumor is confined to 1 or 2 liver lobes
-good prognosis for dogs
-excellent prognosis for cats; curative for benign tumors
-hemorrhage is most common complication
What are the characteristics of non-resectable hepatobiliary tumors?
-approx. 9 month survival
-no effective chemotherapy
-palladia sometimes has some success
What are the characteristics of AGASACA in dogs?
-malignant tumor of the sweat glands in the anal sac
-seen in middle to older aged dogs
-can be unilateral of bilateral
-moderate to high metastatic potential; goes to LNs and lungs
-causes PTHrP-mediated hypercalcemia in 25% of patients
What are the clinical signs of AGASACA?
-swelling, bruising, and bleeding in the area
-scooting
-tenesmus/constipation
-PU/PD if concurrent hypercalcemia
-firm mass in area of anal sacs
-enlarged sublumbar LNs
How is AGASACA diagnosed?
-FNA cytology
-rule out infection
How is AGASACA staged?
-minimum database
-thoracic rads
-abdominal ultrasound
-possible abdominal CT
What are the characteristics of surgery as a treatment for AGASACA?
-good option if there is no metastasis
-want to remove primary tumor with clean margins
-must leave > 50% of sphincter intact to preserve continence
-dogs with larger tumors benefit from referral
What are the characteristics of surgical AGASACA treatment when the sublumbar LNs are involved?
-lymphadenectomy has been shown to benefit survival
-may be associated with major complications
-not all surgeons will remove sublumbar LNs; varies based on training and experience
What are the characteristics of definitive radiation as an AGASACA treatment?
-adjuvant to surgery if margins are incomplete
-kills microscopic disease on the margins
-4 week course
-expensive
-can lead to mucositis, proctitis, colitis, and diarrhea
-improves survival by preventing local tumor regrowth
What are the characteristics of chemotherapy as an AGASACA treatment?
-adjuvant after surgery or surgery/RT
-done when there is metastatic dz
-no definitive survival benefit
-some studies suggest improvement in survival
-can use carboplatin, mitoxantrone, and melphalan
What are the options for AGASACA treatment if surgery is not an option?
-palliative radiation, esp. if patient is clinical
-IV chemo/palladia
-stool softeners
-pain medication
What are the characteristics of AGASACA prognosis?
-good for small tumors treated with definitive surgery
-early detection is key
-guarded to poor prognosis for non-resectable and metastatic disease
What are the negative prognostic indicators for AGASACA?
-large primary tumor size
-metastasis
-no surgery for smaller masses
-palliative chemo only
What are the characteristics of perianal tumors in dogs?
-adenomas are more common than adenocarcinomas
-arise from sebaceous perianal glands
-adenomas are testosterone driven and most common in male intact dogs
-female and male neutered dogs should be checked for adrenal tumors
What are the characteristics of perianal adenocarcinomas?
-hormone-independent
-more invasive
-rapidly growing
-moderate metastatic potential to LNs and lungs
What are the clinical signs of perianal tumors?
-one or multiple hairless perianal masses that may be ulcerated
-possibility for pain
-tenesmus possible
How are perianal tumors diagnosed?
-FNA cytology looking for “hepatoid” tumors
-may need biopsy/histopath. for well differentiated adenocarcinomas
How are perianal adenocarcinomas staged?
-regional LN evaluation
-thoracic rads
-abdominal ultrasound
What are the treatment options for perianal adenomas?
-castration for male intact dogs
-surgery
-monitoring if slow-growing and/or significant co-morbidities
What are the treatment options for perianal adenocarcinomas?
-surgery with wide margins
-possible radiation therapy
-possible chemotherapy
-NOT responsive to castration
What is the prognosis for perianal tumors?
-excellent with surgical removal for adenomas
-variable for adenocarcinomas based on tumor size, presence of metastasis, and success of surgery
