Dr. Gottfried K. Duschak, 84, a retired Washington physician and a specialist in cancer detection, died of cancer Monday at George Washington University Hospital.

A native of Austria, Dr. Duschak earned a medical degree from the University of Vienna in 1920. He came to this country in 1940 and lived in New York City and Minneapolis before coming here.

Dr. Duschak began practicing medicine in Washington in about 1942 and retired in 1977 for health reasons.

He was a specialist in x-rays and lung disease as well as cancer detection, and taught in the medical departments at George Washington and Georgetown universities.

From the early 1850s until 1965, he was director of the D.C. Cancer Detection Clinic. He also was physician to the Austrian and German embassies here, where his patients included Austrian President Theodore Koerner and West German Chancellor Konard Adenuaeur. He received the Golden Medal of Honor from Austria.

He was a member of the D.C. Medical Society.

Dr. Duschak also was a graduate of the Vienna State Academy of Music, where he had studied voice.

His wife, Alice, is professor of voice and vocal literature at Johns Hopkins University's Peabody Institute. CAPTION: Picture, DR. GOTTFRIED K. DUSCHAK