Oesophageal cancer-early detection can save lives

Oesophageal Cancer- early detection can save lives

At least half a million of South Africa's current black male population could die of oesophageal cancer (OC) if secondary prevention strategies are not implemented.

South Africa, Iran, Japan and China all have a very high occurrence of OC. Radiation, chemotherapy and surgery offer little help as clinical symptoms appear when it is too late for treatment. By this time, the patient cannot swallow, the tumour is large and the cancer has spread to surrounding tissues. Prognosis is poor. Early detection can save lives and South African scientists have developed a method for its early detection.

Oesophageal cancer is the cancer of the tube connecting the mouth to the stomach. There is more than one type of cancer that affects this tube, but the most important and most commonly diagnosed oesophageal cancer is squamous carcinoma of the oesophagus. Why are only certain groups susceptible? At this stage, diet, cultural practices and genetic predisposition are suspected to be responsible. Scientist, Dr Vikash Sewram is investigating possible culprits in plants commonly eaten for both medicinal and dietary purposes. His team is currently investigating the carcinogenic potential of Pteridium aquilinum. In Japan, this plant causes stomach ulcers in rats and its consumption is linked to a high incidence of OC. Typically, the young fronds and rhizomes are cooked and consumed either as a dietary supplement or medicinally for stomach-ache and vermifuge. As chemical composition of plants differ with geographical region, Sewram's group are conducting their own research in the Transkei (Eastern Cape of South Africa) and are establishing the extent to which local communities in the Transkei are exposed to the plant.

Left, the polyurethane foam sphere on a string and right, the sphere as it appears compressed inside a gelatine capsule While researchers seek the causes, early detection methods become an important strategy in the battle against OC. Using very simple and very cheap technology, Francois Venter has developed a method that makes early detection of OC possible. The technique detects changes in the cell lining or luminal surface of the oesophagus. These changes may be an early indication of a precancerous state. How does it work? A small polyurethane foam sphere (brush) with a diameter of about 26mm and attached to a thin string is compressed inside a size 00 gelatine capsule. The subject swallows the capsule, the gelatine dissolves, releasing the brush which expands to its full size. As the brush is withdrawn by pulling on the string, it collects a sample of the cells lining the oesophagus. Glass slides are prepared of these cells and then under a microscope, Venter is able to identify abnormal cell growth.

After collecting a cell sample, slides are prepared and viewed under a microscope Venter tested his method on 152 volunteers who showed no symptoms of OC. The volunteers were from Qolora in the Transkei where a high incidence of OC occurs. Venter identified that only 23% of these volunteers had a normal cytology (cell populations on the slide), while the rest of the group displayed various degrees of abnormal cell growth. Detection and confirmation of precursor lesions and abnormalities does not necessarily indicate that an individual will develop OC, but is a signal that the person is at a high risk of developing OC. This affords the opportunity to have the patient's condition surveyed so that early treatment can be possible if necessary.

In Venter's test, the group showing high-grade squamous epithelial lesions (and this was 27% of his group), receive immediate further monitoring by brushing and endoscopic examinations to determine the exact position of the abnormality. Tissue samples are taken and examined microscopically to confirm the cytological findings. One such person out of Venter's test group has been identified and further treatment can take place.

This technique is now being employed by scientists and health care professionals at the Umtata General Hospital. Says Venter: "I sincerely hope that this method will be used for routine testing by clinics, hospitals and health workers, as similar methods are used with great success in the Eastern countries like China and Japan." Venter will be continuing with further tests in the Transkei region of the Eastern Cape Province of South Africa. With the support of the Medical Research Council of South Africa as well as, the Cancer Association of South Africa (CANSA) he will extend this research to the Western Cape Province of South Africa for at least the next three years starting this year.

Mr Francois Venter and Dr Vikash Sewram are Medical Research Council (MRC) Scientists with the PROMEC Unit. This article has been adapted from the MRC News publication.

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