Palliation of Oesophageal Cancer
There are a minority of patients that cannot undergo some type of surgery either because of weakened physical state or advancement of disease. In cases like these, radiation can offer a significant amount of relief. Dysphagia is satisfactorily relieved in approximately 80% of the patients that undergo radiation therapy. However, the relief achieved from radiotherapy is many times short lived. In half of patients, tumour regrowth may occur 6 months after radiation therapy has been completed.
Radiation therapy should not necessarily be divided into strict definitions of palliative treatment and curative treatment. Although in some instances this may be the case, it is always true that palliation can be achieved while still attempting to cure. Therefore, treatment schedules and dosages of external beam radiation (discussed in more detail later) are adjusted to the patient's tolerance. An approximate curative effort may be a total dose of 6000-6400 cGy in 180-200 cGy daily fractions, 5 days a week, for 6-7 weeks. On the other hand, pain relief may be more rapidly attained by increasing the daily dose to a total dosage of 4000-4500 cGy in 220-259 cGy daily fractions, 5 days a week.
Intracavitary radiation has been shown to be an effective tool in the palliation of dysphagia. Intracavitary radiation (described in more detail later) involves placing a radioactive source in or around the tumour. This radiation technique doesn't affect the radiosensitive adjacent structures such as the lungs and spinal cord that may be affected with external beam therapy. This therapy is extremely desirable for debilitated patients that cannot undergo even non-invasive yet somewhat further debilitating procedures such as external beam radiotherapy or in patients who have had the maximum tolerable safe dose of external beam radiation.
Many nonrandomised studies have reported various dosages and designs. Most report single fraction by intraluminal brachytherapy. Dosages ranging from 10-20 Gy with length of relief of dysphagia increasing as the dosage increases. Doses of greater than 20 Gy will cause severe damage to the esophagus and this level should not be exceeded.
However, fractionating the dose may increase the tolerance and effectiveness.
Obviously, the patients who undergo this type of treatment alone are in an advanced stage of this disease, but with this type of palliation, dysphagia-free survival can last up to 12 months in 25-40% of patients. Complications are low and include most likely fibrotic strictures that can be effectively managed with dilation.
Laser therapy is another option for relief of dysphagia. This therapy is indicated when obstruction of the oesophagus occurs and patients are unresectable. A neodymium:yttrium-aluminum-garnet (ND:YAG) laser is used for small obstructive tumours of the middle to lower thirds of the oesophagus. The goal of this procedure is to degrade the tumour with high power (80-120 watts) and short power durations of approximately one second (range from <1-2) without general anaesthesia. Energy of the Nd-YAG laser applied through quartz fibers which is directed through the operating channel of the fiberoptic endoscope. The tip should be approximately 5-8 mm from the tissue. It is directed in a retrograde fashion when possible to avoid an obstructive accumulation of necrotic tissue and to reduce the likelihood of oesophageal perforation. However, because of the completely obstructive tumour in many cases, therapy is administered in an antegrade fashion. Treatments may be repeated and many times are repeated anywhere from 1-6 times (average 2-3) to provide luminal patency. The treatments to reestablish luminal patency are required on average every 4 weeks (range 3-10 weeks). Mortality risks with laser therapy are relatively insignificant and morbidity risks are also low (<5%). Complications that have arisen include oesophageal perforation, bacterial infection, abdominal distention, and either massive or acute haemorrhage.
Photodynamic therapy (PDT) is a fairly new technique used in the treatment of early stage oesophageal cancers and the palliation of dysphagia. The procedure is based on the principles that malignant tumour cells have a unique vascular and lymphatic system and that the photosensitiser used will absorb light and produce oxygen radicals. A photosensitiser such as, dihematoporphyrin ether, is given intravenously. After 2 or 3 days it is retained in the malignancies in a much higher concentration than in normal tissue of the body. Then, a low power laser system that produces red light, is delivered to the tumour by a flexible endoscope. The photosensitiser absorbs the red light and produces oxygen radicals which destroys the tumour. A red laser light wavelength of 620-630 nm is used. The power is in the range of 400-500 mW per centimeter of diffusing fiber and light doses of 300 joules per centimeter of diffuser tip is applied.83
Two to three days after PDT, esophagoscopy is repeated and the necrotic tumour tissue is removed. PDT is usually repeated one month after the initial treatment and indefinitely if indicated.
Complications can include development of fistulas and pulmonary complications. Edema of hands and face and sensitivity to sunlight after PDT is a common complaint.
Photodynamic therapy has a very high 5-year survival rates, 62%, of patients with stage I tumours. In addition, patients with stage I tumours have also experienced clinical complete responses. It is a treatment that can be used in conjunction with chemotherapy and be repeated indefinitely.
The purpose of a stent is to bridge the obstruction in the oesophagus with a rigid device that will allow for a re-establishment of luminal patency. The evolution of the stent has gone from decalcified ivory, to plastic, to the modern and widely accepted silicon coated wallstentŪ. This flexible self-expanding stent is made up of two layers of superalloy monofilament wire with a layer of silicon in between. The addition of the polymer in between the layers of mesh wire is a relatively new addition that extends the time the stent can be beneficial to the patient by preventing tumor overgrowth through the holes in the wire mesh.
The 4, 6, or 9 cm length stent comes in a system of tubes that allows for safe insertion. The insertion system is approximately 13 mm (38F) in diameter. Patients are placed under local or general anesthesia and the stricture is dilated to 42-45F using a flexible gastroscope and Savary bougies. The lesion is marked and insertion of the WallstentŪ is carried out under fluoroscopic control. The physician must wait between 5 to 10 minutes before removing the introducer so as not to dislodge the implanted stent. Once the stent is in place, it cannot be moved or repositioned. Once inserted and fully expanded, the inner diameter of the WallstentŪ is about 18 mm and outer diameter is 20 mm. Its ends flange out and measure up to 28 mm to allow the prosthesis to anchor to the wall of the oesophagus. After placement, a chest roentgenogram or barium oesophagography is performed to reconfirm stent position.
The procedure is very often successful, >90% and patients can begin the routine of eating normal foods. Patients complain of chest pain in almost 100% of the cases because of the stretching of the stricture. Also haematemesis and nausea are possible complications.
The insertion of self-expanding metal stents does not preclude further with chemotherapy or radiation. Although the tumour shrinks during these treatments, it has been found that the ability of the WallstentŪ to expand and its flanged ends allow it to stay anchored and migration does not occur.