WASHINGTON, April 17--Fidel Castro spoke out strongly today against dictators and in favor of a free press.

Cuba's strongman and prime minister also said he doesn't want any handouts from the United States--just better trade relations and U.S. tourists seeking "a good time."

Castro lectured his hosts on Cuban economic problems and said his country needs a "just treaty of commerce" with the United States to get money for building factories and reforming agriculture.

He also said one of his major goals is to ward off Communism by wiping out poverty and hunger. The heavy-bearded revolutionist spoke to the American Society of Newspaper Editors while friends and foes of his regime demonstated, in an atmosphere of some tension, outside the hotel.

Cancer Discovery Made

ATLANTIC CITY, N.J., April 17--Tritium, an ingredient of the fearsome H-bomb, offers new humanitarian aid as a sleuth in the quest for the cause of cancer.

This was reported today by researchers of the Sloan-Kettering Institute of New York to the closing of the 43rd annual meeting of the Federation of American Societies for Experimental Biology.

Drs. Ellen Borenfreund, Herbert S. Rosenkranz and Aaron Bendich said tritium now offers a new and improved method for the radioactive "tagging" or labelling of the genetic material of cells and viruses so scientists can trace its activity, sight unseen.