CHINA IS TRYING to develop the same techniques to stamp out cancer that it developed so successfully to wipe out previous epidemic diseases -- malaria, tuberculosis, hookworm.

In the remote Lin Xian valley, where the Taihang Mountains rise out of a flat plain about 600 miles southwest of Peking, a campaign has been underway for five years -- a campaign specifically against cancer of the esophagus, the pipe that takes food from the mouth to the stomach.

In the villages you will see the barefoot doctors daily, busy with propaganda, over the loudspeaker systems, putting up wall posters, visiting and giving "serious talks" to those villagers they suspect may not be taking the precautions they are so busy publicizing. This particular campaign is the first, and it is an experiment that involves 100,000 people.

The fundamental obstacle to preventing cancer is that its causes are complex. Most people who smoke do not get cancer of the lung, and not everyone with cancer of the lung have smoked. Unlike tuberculosis and malaria, where the causes are clear, the causes of cancer are not. So how is it possible to fight cancer by a public health style campaign? What can they tell the people not to do in order to be safe?

What lies behind the remedy is 20 years of research by a team of Chinese scientists. The inhabitants of the Lin Xian valley have been crucified by cancer of the esophagus for centuries (there is a reference to it in writing of 2,000 years ago) -- but just that cancer, not any other. One in 10 dies of it, 100 times more than is normal. At one end of the valley the rate rises so that, in an area only 20 miles square, one in four people dies of this cancer. Outward from the valley, in concentric belts, the incidence of the cancer steadily decreases, until at about 300 miles it approaches normal levels.

A team of scientists was created by bringing eipdemiologists, virologists, chemists, geologists from Peking and Chengchou (the capital city of Honan Province) to join the pathologists and surgeons of the local hospitals. They began their work in 1958.

The concept that they were working with was that they were not going to find a single cause of cancer. There would be a multiplicity of causes and they believed that many factors had to operate together before a cancer would begin. b

There would be causes in the environment perhaps, carcinogens or viruses. There could be causes in the peasants' lifestyle, and these would need to combine with some weaknesses in a particular person's internal defense system for the cancer to grow. The scientists believed that if they could find just some of the causes and remove them, then that might be enough.

During the first years of their experiment they could find no obvious causes. The area was free from industrial chemicals. There seemed nothing particularly special about the soil, save that it was low in a trace element, molybdenum (a metal), and the well water was slightly rich in nitrate and nitrite.

The scientists studied the peasants' livestyle in detail. The local way of life had evolved from the need to store food for the severe winter when nothing grew. The scientists became suspicious of some aspects of this lifestyle: for example, the way that the peasants preserved persimmons, a soft fruit like a tomato, was to warp them in a paste of sharp-pointed wheat husk. The fruit was dried in the sun to a rock-hard cake, which would keep it for 10 years. The peasants used to eat the whole abrasive cake, and the scientists thought the repeated scratching of the food pipe was a cause.

A way the pesant used to pickle cabbabe was suspected by the scientists. The cabbage was rotted down into a kind of sauerkraut by simply holding the leaves under water with a stone until they had turned into a strong and moldy acid pickle. It was a local delicacy.

It had long been said by the people outside Lin Xian that their special cancer was because they always ate their food too fast and too hot, that they were continually burning their esopohagus. That was one of the easiest things for the research team to investigate, and their findings showed that, although the people did bolt their food, it was no hotter there than elsewhere in China.

But the research had just gotten started when the Cultural Revolution interrupted it, in the mid-60's. The universities were closed, western books burned. The research in Lin Xian was stopped and the team dispersed into the vastness of China, to have their minds "remolded." Only in the early '70s was the work begun again.

The scientists were found and brought to Peking before being sent again to Lin Xian. Dr. Li Bing, the director of research at the Cancer Research Institute of Peking, reassembled the team.

One of the team in Lin Xian, Dr. Liu, a pathologist working on the incidence of cancer of the gullet in chickens, said:

"We feared criticism. If you were working on experiments or in research, you 'desired personal power and fame.' The effect on my research was considerable. My work on the chickens stopped. I couldn't continue. You couldn't open a book without somebody criticizing you. You couldn't look at a reference book in broad daylight! You read them on the sly at night. We did routine work every day, but no research."

Dr. Liu's work had begun when a peasant had been asked if any of his family had difficulty in swallowing. He had said, "No, but one of my chickens has." hThat chicken, when examined, was found to have cancer of the gullet. And soon Dr. Liu had established that the chicken cancer and the human cancer occurred together.

In 1970, Dr. Liu could resume his work on chickens. He organized a survey of the 15,000 chickens of the most afflicted commune and he found that the chickens had the same incidence of cancer as the humans did. He got the barefoot doctors from the counties where the human cancer was different from that of Lin Xian to go looking for chickens with cancer. Some 40,000 chickens were examined. The match between the incidence of human and chicken cancer was very close.

tThe questions this research raised were these: Was the cancer being passed from the chickens to the humans? Or from the humans to the chickens? Or were they both catching it independently from something in the environment? oA migration allowed an answer to be found.

Some 50,000 people had to move from a valley nearby because it was to be made into a reservoir. They suffered from the cancer. They were moved 300 miles to a district with little esophagal cancer. They did not take their chickens with them,but were given new chickens when they got there.

Among the migrants' new chickens were found 12 cases of cancer -- a total contrast to the surrounding countryside, were the same stock of chickens were totally free. So it seemed certain that the chickens were getting it from the people and that most likely its origin was in the scraps and leftovers the peasants fed to them. So attention was focused on the Lin Xian diet.

During the Culteral Revolution, a British scientist, Dr. P. N. Magee, had published a report which the Chinese found extremely relevant. A certain group of compounds, called the nitrosamines, caused cancer of particular organs of experimental animals. Some of these compounds specifically went for the esophasgus. These compounds all have a similar structure -- three branches forming a letter Y. One branch can be built from nitrite, and the other branches can be any amine fragments which are often the products of decaying protein. As there seemed to be no suspicious nitrosamines in the valley, the scientists wondered if a compound could be being made inside the pesants, that perhaps in a stomach digesting local food these vicious chemicals were being built up.

So an experiment was done on five pigs waiting to be butchered at the main slaughterhouse in Lin Xian. Small amounts of nitrite and amine fragments (made from local wheat) were added to the pigs' food, and they were allowed to digest their spiked meal for an hour. As a pig was butchered the stomach was given intact to a scientist, who rushed it on his bicycle to the laboratory. Analysis showed that the chemicals had linked to become nitorsamines.

So the hunt began for the fragments from which it was possible that the nitrosamines were being made. It was found that the peasants carried in their bodies much more nitrite than is normal. But why? Their vitamin C level was measured, and that turned out to be extremely low. But when 27 women were given extra vitamin C for a week their nitrite levels dropped to almost one-third. It seemed that lack of vitamin C interefered with the body's natural defense againt nitrite.

So two unrelated facts now fell into a pattern. The research team had already found that the soil was low in a trace element, molybdenum, and from reading western research they saw the significance of that; for low molybdenum was affecting the plants and, without enough molybdenum, plants concentrate nitrite in their leaves -- and they make less vitamin C.

So the people were doubly at risk from nitrite. It was concentrated in their vegetables, and without vitamin C their bodies' defense systems could not protect them from it. It became clear where one part of the ntrosamine molecule could come from. Where did the rest, the amines, come from -- the fragments that come from decaying protien?

Mold is extremely common in the valley and moldy foods were a part of the diet. The scientists examined the bread the peasants used to make from ground corn flour. They used to make enough at one time to last them for three weeks.

Although the bread started to go moldy after a few days the peasants seemed to lke that (as some people like the mold on blue cheese). When bread was allowed to go moldy in the laboratory it was found that hundreds of samples of the bread were quite harmless. A local fungi caused the levels of amine fragments to increase rapidly. One fungus, f moniliforum , was especially powerful in creating amine fragments. So they believed they had uncovered the source of the second half of the nitrosamine from the action of fungus on food.

Then they discovered something unexpected -- a result which may have significance outside the Lin Xian. Rats eating moldy bread spiked with nitrite got cancer. That proved their idea about nitrosamine formation. But the control rats who were on the moldy bread alone got cancer too! The molds could create the nitrite part of the nitrosamines themselves. The Chinese found that some molds can make nitrosamines directly and possibly are producing their own cancer-causing agents, as yet unidentified. One of the molds in the pickled vegetables, G. candidum , was particularly active.

In order to find which molds are dangerous the scientists have started growing pure strains of the local fungi. But the work will take years, for there are 10,000 local fungi, and each experiment takes two years of waiting tosee whether the rats will develop cancer.

The campaign against this cancer is mobilizing the 70,000 villagers at the worst affected end of the valley. In each village the barefoot doctor is responsible for constant propaganda, to remind residents continuously only to drink the purified piped water which hashad nitrate and nitrite removed, to eat fresh vegetables, not to make the persimmon cakes or the pickled vegetables that the locals like to make so much. And particularly not to eat moldy food.

The pace of the work has been very fast. Work could only begin on the fungus and nitrosamines in 1970, and yet by 1974 the anticancer campaign had begun.

The treatment of those who have already developed cancer is much the same as in the West: an X-ray to determine where the cancer is and an operation to remove it. The Chinese results are as good as in the West: 42 percent of the patients survive five years. The striking part of the curative work in Lin Xian has been the efforts to deterine the cancer at a much earlier stage than wehn the patient feels difficulty in swallowing, from then the cancer is approaching its final stage.

In Lin Xian they have devised a simple test which the barefoot doctors now adminster. It is painful. A small balloon covered with fine mesh is swallowed to the stomach. The balloon is inflated and pulled up the esophagus. It takes a scraping of skin on the way up, and tissue fragments are then put on slides and stained. Cancer cells show up with their large blue nuclei.

So far about 25,000 people have been balloon tested. The results of these tests contained two surprises. They found that 80 percent of the cases they were detecting were at the earlier stage -- before symptoms developed -- and so they had the best chance of being cured by surgery. They also found that the cancer was preceded by a precancerous condition called hyperplasia, a thickening of the internal covering of the esophagus.

Treatment of hyperplasia with traditional herbal drugs has been widespread. The two most common are Kongai i San (literally, "anti-tumor drug") and Don Ling Tsao . The traditional doctors of China did not know of the anti-tumor properties of these drugs; they used them "to draw out high te temperature."

There are many people lon these drugs whose hyperplasia has been cured and many whose hyperplasia has not progressed to cancer during periods of up to 16 years. Whether these patients would have stayed well without this treatment is just beginning to be assessed. The comparative clinical trials have just begun. In a one-year experiment, begun in 1977, it was found that, in a sample of 215 people who had no treatment, 30 percent returned to normal in that year, whereas 72 cases on Kongai i San , 75 percent returned to normal.

The scientists' current research continues to look for causes. One recent finding has been that fungus actually grows in the esophagus of most people in Lin Xian. A third of the people have fungus living within healthy esophagal tissue. In those with cancer, 90 percent have fungus in the cancerous tissue. tWhether this means fungus causes cancer as it lives in the tissue, or more simply that cancerous tissue is an easier "home" for fungus to grown in, is the next question.