GENERAL CONSIDERATIONS
Biologic Behavior
- Esophageal tumors are very rare in both cats and dogs accounting for < 0.5% of all cancers
- Female cats are predisposed, but no known breed or sex predisposition in dogs
- Malignant tumors are more common and include SCC, leiomyosarcoma, FSA, and OSA
- SCC is common in cats with the middle 3rd of the esophagus cranial to the thoracic inlet most commonly affected
- Neuroendocrine carcinoma and adenosquamous carcinoma reported in cats
- Sarcomas have been reported secondary to Spirocerca lupi infestation in indigenous areas such as Israel and SE USA
- Spirocerca lupi-induced esophageal sarcomas include FSA, OSA, and undifferentiated sarcomas
- Locally invasive with metastasis to regional lymph node via direct extension or lymphatic or hematogenous routes
- Benign tumors include leiomyoma and solitary extramedullary plasmacytoma
- Solitary extramedullary plasmacytoma have a predilection for the terminal esophagus and cardia
- Paraesophageal (i.e., thymic, heart base, or thyroid) tumors can invade the esophagus
- Pulmonary and mammary carcinoma can metastasize to the esophagus
- Esophageal ADC is possibly associated with cholecystectomy in humans due to bile reflux
CLINICAL FEATURES
+ Clinical Signs
- Non-specific and include debilitation, regurgitation, hematemesis, weight loss, dysphagia, pain during swallowing, and aspiration pneumonia
- Regurgitation may be sporadic due to distensibility of esophagus and slowly progressive disease
- Hypertrophic osteopathy has been reported especially with Spirocerca lupi-induced esophageal sarcomas
- Spirocerca lupi-induced esophageal sarcomas are also associated with esophageal granulomas, aortic scarring and mineralization, and spondylitis of the caudal thoracic vertebrae (T6-T12)
- Esophageal tumors < 2 cm rarely cause clinical signs
Diagnosis
+ Survey Radiographs
- Survey radiograph findings include:
- Gas retention within esophageal lumen
- Esophageal dilation proximal to the mass
- Soft tissue mass displacing the esophagus or extending into the lumen
- Displacement of mediastinal structures
- Lumen irregularities
+ Contrast Esophagram
- Contrast esophagram can be performed ± fluoroscopy
- Esophagram findings include filling defect, stricture, or intraluminal mass
+ Esophagoscopy
- Esophagoscopy provides direct visualization of the mass and ability to collect biopsy samples
- Malignant tumors are usually ulcerated
- Leiomyoma appears as circumscribed submucosal mass movable beneath the mucosal layer
- Several biopsies should be taken due to prominent inflammation and necrosis, but representative samples are difficult to collect
- Iatrogenic perforation is rare with endoscopic biopsy
+ Other Diagnostic Techniques
- Plasma cell tumors may cause hyperproteinemia, hypercalcemia, and monoclonal gammopathy
- Fecal flotation test and examination for Spirocerca lupi ova
- Open surgical biopsy via either exploratory thoracotomy or cervical exploration
TREATMENT
+ General Considerations
Treatment is complicated as the majority of cases are advanced at the time of diagnosis
+ Surgery
- Intrathoracic resection is difficult due to poor healing, large resection, anastomotic tension, and poor exposure
- Distal esophagus can be reconstructed with gastric advancement through the diaphragm
- Esophageal reconstruction has been reported with muscle flaps or microvascular transfer of colon or small intestine
- Results of esophageal reconstruction are variable
- En bloc esophageal resection is associated with excellent local control and > 50% long-term survival
- Partial esophagectomy with primary esophageal closure has been reported in the management of 6 dogs with Spirocerca lupi-induced esophageal sarcomas with good postoperative recovery and function, and survival times ranging from 2 to > 20 months
- Palliation with enteral nutrition (via E- or G-tubes) or self-expanding intraluminal stent
+ Radiation Therapy
- Indications: tumors of the cervical esophagus
- Intrathoracic esophageal tumors should not be irradiated due to poor radiation tolerance of the lungs and heart
+ Chemotherapy
- Unknown
- Doramectin (200 µg/kg q 2 weeks SC for 3 treatments) used successfully in dogs with Spirocerca lupi esophageal granulomas
+ Photodynamic Therapy
Photodynamic therapy using photofrin as a photosensitizer has been described in the management of 1 dog with esophageal SCC with PR and 9-month survival time
+ Prognosis
- Prognosis is poor for malignant esophageal tumors due to difficult surgical resection and high metastatic rate
- Prognosis is good for benign lesions following complete resection
- 5-year survival rate is < 20% in humans using a combination of surgery, radiation therapy, and chemotherapy