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Oesophageal neoplasia is very rare accounting for less than 0.5% of all cancer, except where Spirocerca lupi is endemic (Africa and South-eastern USA). The most frequently reported types of neoplasm are:
- Squamous cell carcinoma - usually appears as an annualar thickening in the middle third of the oesophagus, anterior to the heart.
- Leiomyosarcoma
- Fibrosarcoma
- Osteosarcoma
- (Plasmacytoma)
- (Local invasion of paraoesophageal tumours e.g. thryoid)
- (Leiomyoma - benign, most frequently in the caudal oesophagus and cardia)
Signalment
- Most are older in age
- No sex predilection
- No breed predilection
Description
In Africa and South-eastern USA the parasitic worm Spirocerca lupi can cause oesophageal fibrosarcomas and osteoasarcomas. This is most likely due to the parasite secreting a carcinogen. The aetiology of carcinomas in other areas is idiopathic though potentially ingestion of carcinogens may be involved.
Diagnosis
History and Clinical Signs
Indicative of partial or complete upper gastrointestinal obstruction
- Signalment as above
- Non-specific signs of general poor condition and weight loss
- Dysphagia/Pain on swallowing
- Regurgitation
- Aspiration pneumonia (secondary to regurgitation)
- Hypertrophic osteopathy as a paraneoplastic syndrome - particulary those with sarcomas with Spirocerca lupi aetiology
Plain Radiography
A mass, intra-luminal gas retention or oesophageal stricture with a cranial dilation are not always visible. Contrast studies may be required to define mucosal irregularities and strictures. Swallowing defects and regurgitation can be assessed via fluoroscopy.
Advanced Imaging Techniques
CT and MRI can be useful in defining the full extent of the lesion.
Endoscopy and Biopsy
Endoscopy can allow visualisation of the mass. Several biopsies should be taken.
Surgery and Biopsy
Samples can also be taken via thoracotomy or cervical exploration.
Faecal Analysis
Ova of Spirocerca lupi can be found in the faeces.
Treatment
Surgery
Complete tumour excision with oesophageal anastomosis is frequently problematic due to difficulties obtaining complete margins and complications of reconstruction. There can also be complications in the healing of particularly the thoracic oesophagus. One study of 6 dogs who underwent partial oesophagectomy due to Spirocerca-related oeophageal sarcomas reported a median survival of 267 days. 5 of the 6 cases also received doxorubcin. Another study of 4 dogs with oesophageal leiomyosarcoma reported potential long term resolution of clinical signs following marginal surgical resection despite incomplete margins if the tumour was low grade (all were grade 1). Oesophageal bouginage can reduce signs such as regurgitation. Oesophagotomy and gastrostomy tubes can also be used for short term palliation.
Chemotherapy
Rarely reported.
Radiotherpy
Limited in the thoracic oesophagus due to poor tolerance of the heart, lungs and other surrounding tissues.
Prognosis
Often poor as usually in advanced stages on time of diagnosis therefore limiting resection options. In addition, metastatic rate is high: malignant tumours are locally invasive and metastasis occurs via draining lymph nodes (Cervical and Prescapular lymph nodes in the cervical oesophagus and Mediastinal in the thoracic oesophagus) and haematogenous spread to distant areas.
References
- Morris J, Dobson J (2001) Gastrointestinal Tract, in Small Animal Oncology, Blackwell Science, pp 125-127
- Ranen E, Sharmier M. H, Shahar R, et al, (2004), Partial Esophagectomy with Single Layer Closure for Treatment of Oesophageal Sarcomas in 6 Dogs, Vet Surg 33:428-434
- Withrow S. J, Vail D. M (2007), Cancer of the Gastrointestinal Tract, in Withrow and MacEwen's Small Animal Clinical Oncology, fourth edition, Missouri, Saunders Elsevier, pp 477-478