Oesophageal cancer originates from the cells lining the inner mucosal layer of the oesophagus. As it grows, it spreads through the muscular layers of the oesophagus before metastasizing to lymph nodes and other organs such as the lungs and the liver.
Data from the Singapore Cancer Registry in 2012 shows that oesophageal cancer is the 9th most common cause of cancer-related death in males. The two main histological types of oesophageal cancer are squamous cell carcinoma (SCC) and adenocarcinoma. The majority of oesophageal cancers in Singapore are SCC’s although the incidence of adenocarcinomas is slowly increasing.
Risk Factors and Prevention
Oesophageal cancer usually presents in patients above 60 years of age. It is more common in men and smoking is known to be a major risk factor. Alcohol intake and food preservatives are also believed to convey a higher risk of cancer. Chronic heartburn and reflux disease are associated with Barrett’s oesophagus, a pre-cancerous condition which is a major risk factor for oesophageal adenocarcinoma.
An uncommon but important risk factor is previous injury to the oesophagus with chemicals found in household cleaning agents or pesticides. Other rare conditions that lead to oesophageal cancer include swallowing disorders such as achalasia and Plummer-Vinson syndrome and hereditary tylosis.
Prevention of gastric cancer usually focuses on reduction of risk factors such as smoking and alcohol intake, and increasing the proportional intake of fresh fruit and vegetables.
Symptoms and Signs
Most patients present with difficulty swallowing which is usually painless in nature although some patients may also have pain. This difficulty will be initially limited to solids before progressing to intolerance of soft foods and liquids before absolute intolerance to oral intake and incessant vomiting or choking.
The dysphagia is invariably associated with significant weight loss and there may be a prior history of chronic heartburn and dyspepsia. Repeated regurgitation may also lead to pneumonia. Hoarseness of voice may also be present indicating either chronic inflammation or cancer spread.
The diagnostic investigation of choice is endoscopy which allows visual identification of suspicious features of the oesophagus and biopsy for histological confirmation. The typical oesophagogastroduodenoscopy (OGD) examination is performed as an outpatient procedure under sedation and local anaesthesia, taking only approximately 10 minutes. Where endoscopy is not available, barium swallow X-ray of the oesophagus is the usual screening investigation.
Other important investigations to support the diagnosis and to determine the degree of involvement include CT scans, PET scans, bronchoscopy and endoscopic ultrasound (EUS). Some patients may also require a staging laparoscopy or thoracoscopy in order to determine the degree of spread prior to embarking on a treatment regimen.
Treatment of oesophageal cancer should be tailored to each patient depending on the location of the cancer, the stage of the cancer, the patient’s general health and state of nutrition. The overall stage of the cancer is determined by the depth of invasion through the esophageal wall (T-stage), the number of involved lymph nodes (N-stage) and the presence of distant spread (M-stage).
Surgery is the traditional mainstay of curative treatment for oesophageal cancer. Provided the patient’s overall state of health and nutrition is adequate, early-stage cancers are ideally treated with oesophagectomy to remove the oesophageal cancer with its associated lymph nodes. Surgery can be performed through a combination of incisions in the abdomen, chest and the neck, depending on the location of the cancer and the involvement of surrounding anatomical structures. More recently, minimally invasive surgery using combined thoracoscopic and laparoscopic techniques has been shown to be beneficial. After surgery, patients may undergo adjuvant chemotherapy and/or radiotherapy to reduce the risk of recurrence.
Patients with advanced oesophageal cancer or those with poor general health may still be candidates for curative surgery after a period of tube feeding or intravenous feeding combined with neo-adjuvant chemotherapy and/or radiotherapy. Some patients who have significant medical conditions not compatible with major surgery, or patients with cancers in the cervical oesophagus (neck) may be treated with definitive chemoradiation therapy.
When there is evidence of distant spread or spread to vitally important organs in Stage 4, then only palliative treatment is recommended. This may involve chemotherapy or radiotherapy to improve symptoms and reduce the tumour size. Options to improve feeding include endoscopic insertion of self-expanding stents to temporarily ‘reopen’ the oesophagus or insertion of external feeding tubes.
Patients with early disease limited to the mucosa (T1) or precancerous Barrett’s oesophagus have the best chance of long-term survival after curative surgery with 5-year diseasefree survival rates approaching 80%. Otherwise, the overall 5-year survival rate for oesophageal cancer after surgical resection ranges from 5% to 30%. Early diagnosis is vital as the options and results of treatment vary greatly depending on the cancer stage.