The first successful chemical treatments are being reported in some forms of lung cancer, the deadliest and most treatment-resistant of all major cancers.

The good news is qualified, because it still affects only small numbers of people, and much more testing is needed.

But it is "exciting" because it involves some "firsts" and "offers some hope where there was very little," cancer doctors said yesterday, summing up the latest results from several medical centers.

In three separate developments:

A preparation of antigen (disease-fighting material) from lung cancer tissue -- developed by Dr. Ariel Hollinshead of George Washington University here -- has achieved a five-year survival rate of 80 percent in 52 patients treated after lung surgery at the University of Ottawa in Canada.

National Cancer Institute doctors here reported that 108 patients with small or oat-cell cancer -- the form of lung cancer whose cells grow the fastest -- have remained alive for two to seven years after diagnosis because of hospital treatment with combinations of anti-cancer chemicals. The 108 represent only 7 to 10 percent of all patients treated, but all were diagnosed too late for surgery to help, and virtually all, it is certain, would have been dead by now without the chemotherapy.

Dr. Gerald Vosika of the University of Minnesota said in the current Journal of the American Medical Association that he cured a patient with still another deadly form of lung cancer -- so-called large-cell cancer -- by use of a chemical called lomustine.

The Minnesota patient died of pneumonia some months ago, after nearly five years of disease-free life. One case does not prove anything in medical science, but the editors of the medical journal nonetheless felt obliged to print this report on what Vosika called "to our knowledge the first patient with lung carcinoma of a type other than oat cell who was cured by a chemotherapeutic regimen."

In all types of lung cancer -- large-cell, small or oat cell, adenocarcinoma, epidermoid or squamous cell tumors, mixed cell cancers -- long-term survivals have been few. There is sometimes success with surgery. There are the occasional John Wayne, successfully operated on in 1964 (though he developed another form of cancer this year), and Arthur Godfrey, who had part of a lung removed in 1959.

Far too few cases are found early enough for surgery, however. And, for all lung cancer patients, early and late, overall five-year survival between 1967 and 1974 was only 9 percent among whites and only 6 percent among blacks. Only the far less common cancer of the pancreas was deadlier.

But "increasingly," Vosika wrote, there are "reports of effective multi-drug chemotherapy programs for small-cell carcinoma of the lung," with "prolonged survival and possible cure."

Building on a chemotherapy-radiation combination tried by Dr. Ralph Johnson at the National Cancer Institute, Drs. John Minna and Martin Cohen of the institute's Washington Veterans Hospital cancer research unit began using various anti-cancer drugs in sequence.

Adding up reports from many hospitals, Minna said yesterday that "of all comers" among patients diagnosed too late for surgery, "probably 10 percent now have survived two years or more." Of 100 such patients at the VA hospital, said Cohen, "we have seven now disease-free for three to seven years. Equally good results are being reported with chemotherapy-radiotherapy combinations."

These treatments have not worked in most other lung cancers. But Dr. Hollinshead had made her anti-tumor material from lung cancer of all forms, and it has been tried in all forms in Ottawa. Another trial in 80 patients, under way for two years at Roswell Park Memorial Institute in Buffalo, N.Y., is producing rusults much like Ottawa's at the same stage.