Dr. Lois Irene Platt, 70, professor emeritus of the George Washington University Medical School where she was in charge of the cytology laboratory in the pathology department, died of cancer Dec. 24 at Northern Virginia Doctors Hospital.

She was with the pathology department from 1954 until retiring in 1974. In addition to her laboratory work, she taught in the school of cytotechnology for deaf students and took part in postgradulate education for area physicians.

She joined the Warwick Memorial Clinic for Cancer at George Washington University in 1949 as a cytologist and clinical instructor in surgery. For two years before that she had been with the National Cancer Institute. In 1948, She founded the Cytology Society of Washington.

Dr. Platt was born in Oil City, Pa. She graduated from Goucher College in Baltimore in 19.1 and for the next 11 years margin biology in Baltimore County high schools. During part of that period, she served during the summer as a research assistant in cytology at the Carnegie Institution at Cold Spring Harbor, Long Island, N.Y.

Dr. Platt went back to school to earn a degree from the University of Maryland Medical School in 1946. She served her internship at the old Garfield Hospital in Washington.

In addition to her work at George Washington University, she was a consultant to the Veterans Administration, the Ladson Cytologic Clinic and the C&P Telephone Co. medical department. She published numerous articles in medical journals.

Dr. Platt received a number of awards, including the St George Medal of the American Cancer Society. She was a fellow of the U.S. Public Health Cancer Association. She also had been honored by the Friendship and Potomac Lions clubs and the D.C. Optimist Club.

Since her retirement, Dr. Platt, who lived in Fairfax, spent several days a week adressing various groups in the Washington area on cancer, particularly breast cancer. At the time of her death, she was vice president of the D.C. Division of tthe American Medical Association, the D.C. Medical Society, the Southern Medical Association, the American Society of Cytology, the New York Academy of Sciences, the American Association for the Advancement of Science, the American Medical Womens' Association, the American Association for the Study of Neoplastic Diseases, the Public Health Cancer Association and the Soroptimist Club of Arlington.

There are no immediate survivors.

It is suggested that expressions of sympathy may be in the form of contributions to the American Cancer Society. CAPTION: Picture, DR. LOIS IRENE PLATT