A Harvard-affiliated hospital this weekend received a $5 million grant to help finance a cancer research building that has been under construction since January.

The Dana-Farber Cancer Institute will use the grant from the Louis B. Mayer Foundation to help offset the $28 million building costs.

The building, which hospital officials said will be completed by the spring of 1988, will be used for scientific and medical research. It will house a laboratory named for the late Louis B. Mayer, co-founder and former chairman of the Metro-Goldwyn-Mayer motion picture company.

Dr. Sidney Farber, who founded the cancer institute in 1942, treated Mayer during his battle with leukemia, until Mayer's death in 1947. Farber, a Harvard pathologist and physician, was the first doctor to use chemotherapy successfully against childhood leukemia.

The foundation "wanted to honor the relationship between Louis B. Mayer and Dr. Farber," said Lori Krupnick, Assistant Director of Public Affairs for the hospital. She said the grant is the largest amount given to the center since 1982.

Since its establishment in 1947, the Mayer Foundation has sponsored research and patient care at facilities that include the Farber Institute and the Motion Picture Country Home, California, a non-profit hospital and residential community affiliated with MGM studios.

Foundation officials could not be reached for comment yesterday.

"It was Dr. Farber's compassion as much as his brilliance that made him the single most important human being my father had ever known," Irene Mayer Selznick, Mayer's daughter and president of the foundation, said on Saturday during a ceremony held by the hospital to acknowledge the donation.

Emil Frei, Smith Professor of Medicine and Director and Physician-in-chief of the Institute, also spoke and expressed hope for cancer research opportunities.

"We're as committed as ever to attempting to understand how the cell works and what causes it to become malignant," said Frei. "Based on that understanding, we will be able to develop new and improved treatment programs for children and adults with cancer."