The discovery of 16 cancer cases in and around the small community (20,000) of Rutherford, N.J., has triggered the biggest medical manhunt since Legionnaire's disease struck the guests of a Philadelphia hotel three years ago.

It's a manhunt that's reached into the offices of more than 50 physicians and combed the halls of 11 hospitals in two counties.

It also has gone across the Hudson River to New York City's Sloan-Kettering Memorial Hospital and Columbia-Presbyterian Hospital to see if there are undetected cancer cases among the people living in the environs of Rutherford.

"We're in a case-finding operation right now," said Dr. Ronald Altman, chief epidermiologist for the state of New Jersey. "We're looking for a common thread, if there is one."

The manhunt involves the health officers of six towns, two counties, the state of New Jersey, the National Cancer Institute in Bethesda and the Communicable Disease Center in Atlanta.

Medical sleuths are combing morgues, hospitals, schools and doctors' offices in a 10-mile radius of Rutherford to see if the 16 cancers are linked.

Doctors already figure that 10 of the 16 cancers are unrelated. At least four of the persons were identified as living in Rutherford when they lived at least 10 miles away. Three are victims of Hodgkin's disease, a form of lymph cancer that occurs in the general population in approximately the numbers striken in Rutherford. Three others are leukemias in older people who may have had the disease for some time but have had it diagnosed only in the last month.

"Let's face it," said Dr. Glenn Cladwell of the Communicable Disease Center. "One in four of us is going to get cancer. We have to remember that in looking at the statistics in Rutherford."

What worries doctors about the Rutherford experience are six leukemias found among the pupils in Pierrepont Elementary School in Rutherford. Two of the six died.

A 17-year-old girl who baby-sat for the two dead children became the most recent victim of leukemia in the town. Curiously, she went to the same school as a youngster.

State epidemiologist Altman said he thinks the amount of cancer around Rutherford in general will not be found to exceed that of the normal population. "But there may be an excess at the school," he added ominously.

On Tuesday night there will be a meeting at the home of Kay Wills, who runs an organization called Mothers Matter, to discuss what has happened at the school. The meeting has been called to head off the panic that has built up among some of the parents and pupils in the school, which houses 776 students.

"We've got to help those people who read the papers and think there's cancer in the school," she said.

The mothers of the two Pierrepont pupils who died of leukemia wihtin five months of each other a little more than a year ago where the people who called attention tow what was happening in Rutherford.

One of the two mothers, Vivian Cleffi, went to school superintendent Luke Sarsfield less than a month ago with the names of more than 10 cancer victims she said she had known in Rutherford.

Sarsfield took the names to Health Officer Henry McCafferty, who took to his car and telephone to verify Mrs. Cleffi's chilling news. McCafferty needed almost two weeks to check out Cleffi's suspicions, which unreeled like a horror movie.

The cancers in Rutherford aren't the first cancer clusters to be witnessed in the United States. There are at least a dozen well-known and well-documented cases of cancer-cluster in the last 20 years, starting with the leukemias of six school children in Niles, Ill., 20 years ago.

"and we find two deaths, one a 92-year-old man who smoked four packs.

"We still average one call a week about cancer clustering," said Dr. Caldwell at the Center for Disease Control. "Usually, it's an old woman calling to tell us that everybody in her church is dying of cancer.

"We investigate," Dr. Caldwell said, a day and the other a 62-year-old woman with a history of breast cancer."

nonethless, Dr. Caldwell has dispatched two epidemiologists familiar with cancer clustering to New Jersey to look into the Rutherford case. One reason the CDC is investigating Rutherford is to allay the fears of the town. The other reason is the hope that they may find something that links the 16 cancers.

No common clue has turned up in any of the other clusters investigated by the CDC in the last 10 years. There have been leukemia outbreaks in Buffalo, Albany, Green Bay, Los Angeles and Atlanta. No evidence was ever gathered in any of these outbreaks to fix blame for any of the cancers.

In the search for a cause of the cancers, one of the first things doctors have done is test for chemicals in the air - especially benezene. Benzene is one of the few chemicals implicated as an invironmental cause of leukemia.

Doctors found no traces of benzene in the air around Rutherford, even though there are at least 10 chemical plants in Bergen and Passaic counties that use benzene.

One report suggested "something" in the air was killing the trees around Rutherford, which reminded doctors of at least two past cases of cancer clusters where rumors about the disease spread faster than the cancers.

A cluster of leukemias in North Dakota took place at the same time the willow trees died. Another happened in Kansas City when the oleanders pollutants were causing the cancers proved as unfounded in both cases as they did for the deaths of the trees and shrubs.

"We have to approach this case carefully, to make sure we do a thorough job," Dr. Caldwell said. "One thing we have to remember . . . we still don't know what causes cancer."