The arms race over the future of cancer care in Boston intensified on Wednesday when Dana-Farber Cancer Institute announced the largest single gift in its 79-year-history, for its planned $1.68 billion, 300-bed cancer hospital.

Dana-Farber, which wants to build the hospital on the site of Joslin Diabetes Center in the Longwood Medical Area as part of a partnership with Beth Israel Deaconess Medical Center, didn’t disclose the size of the gift. The donors, Josh and Anita Bekenstein and the Jonathan and Jeannie Lavine family, want to keep the amount private.

Last year, the Pan-Mass Challenge fund-raising bike-a-thon gave Dana-Farber a $78 million gift that the institute said shattered the previous record for a single donation. The latest gift surpasses that and will give the Bekensteins and Lavines naming rights to the new freestanding cancer hospital, which is scheduled to open in 2031.

Josh Bekenstein, the current chair of the Dana-Farber Board of Trustees, was a founding partner of Bain Capital. Jonathan Lavine is the founder of Bain Capital Credit.

Also on Wednesday, Mass General Brigham announced a $35 million gift from Irving Oil, which is based in New Brunswick, Canada, to fight cancer in honor of its late president and chairman, Arthur L. Irving. MGB is the parent corporation of Brigham and Women’s Hospital and Massachusetts General Hospital.

The corporate offices of Mass General Brigham in Assembly Square in Somerville. (Lane Turner/Globe Staff)Lane Turner/Globe Staff

For about 30 years, Brigham and Women’s had collaborated with Dana-Farber on cancer care before their acrimonious breakup in 2023, when Dana-Farber formed a new partnership with Beth Israel instead. Now, MGB is undertaking its own project to build a new cancer care institute anchored at its two flagship hospitals.

MGB plans to invest $400 million in the institute before Brigham ends its partnership with Dana-Farber in 2028. The project includes renovations at Brigham and complements ongoing construction of the $1.9 billion, 2-million-square-foot Phillip and Susan Ragon Building, which is expected to open in two phases in 2027 and 2030 on MGH’s main campus.

Irving Oil’s gift will establish two major spaces within that building. Both will be named for Irving Oil — one providing urgent cancer care, the other a “healing garden.”

Executives at Dana-Farber and Mass General Brigham applauded the gifts.

“We are deeply grateful for this exceptional, shared commitment from two families who have been profoundly devoted to Dana-Farber,” Dr. Benjamin L. Ebert, president and chief executive of Dana-Farber, said of the joint gift from the Bekensteins and Lavines.

Dr. David P. Ryan, president of the Mass General Brigham Cancer Institute, said Arthur Irving “believed deeply in the power of groundbreaking patient-centered clinical care, and this extraordinary gift in his honor will help us meet patients at moments of greatest need.”

Alan Sager, a professor of health policy and management at Boston University School of Public Health, took a decidedly dimmer view.

While it’s not uncommon for philanthropists to direct their largesse to esteemed teaching hospitals, he said, he would prefer to see major gifts that lead to more equitable health care in the state, address the shortage of primary care doctors, and help community hospitals, from the Berkshires to Cape Cod.

“How much cancer care should be given at major teaching hospitals and how much can and should be delivered closer to where people live, at community hospitals and other hospitals?” Sager said.

The donations come at a time of fierce rivalry between MGB, the state’s largest hospital system, and Beth Israel Lahey Health, the second-largest.

In two years, Dana-Farber will end its long and nationally acclaimed adult oncology partnership with Brigham and team up with Beth Israel to open a new freestanding cancer hospital.

Dana-Farber’s announcement of the divorce in September 2023 stunned executives at Brigham and rocked the hyper-competitive hospital industry. MGB is fighting back with its cancer institute, which the health system is trumpeting in an intensive marketing campaign.

As the latest gifts show, there’s no shortage of prominent benefactors who want to be associated with the hospital expansions.

At MGH, for example, the east tower of the new Ragon building will be named the Herb Chambers Tower, for the auto dealer and philanthropist, who has made a $100 million donation. The west tower will be named the New Balance Foundation Tower, for the running shoe company’s foundation, which also pledged $100 million.

Jonathan Saltzman can be reached at jonathan.saltzman@globe.com.