A week after conducting a second round of layoffs , Mass General Brigham announced a four-year, $400 million investment Tuesday into MGB Cancer as the health care giant braces for its split from Dana-Farber Cancer Institute.

Dr. Anne Klibanski, the system’s CEO, acknowledged the layoffs as she announced the new investment, which involves renovations at Brigham and Women’s Hospital and Faulkner Hospital to create new outpatient spaces.

“As we navigate a period of challenging but pivotal change, I appreciate your continued dedication to our patients and to each other,” Klibanski wrote to employees in a Tuesday message, which was shared with the News Service. “Our reorganization and financial stewardship will strengthen our foundation and enable us to make strategic investment in our patients, our care teams and our mission – preparing us for the ongoing headwinds facing our industry.”

MGB did not specify how many total workers lost their jobs, though The Boston Globe pegged it at around 1,500 positions across the layoffs in March and February.

The system said the layoffs affected mostly management and administrative positions, as MGB contended with a $250 million budget gap over the next two years. MGB argued the layoffs were needed to follow through with planned investments, including for workforce support, new clinical spaces and modernizing facilities.

Klibanski said the $400 million commitment will “advance medical oncology, radiation oncology, cancer surgery, digital pathology, technology upgrades, support staffing, and patient navigation across MGB.” It will also be used to “recruit top oncologists, implement digital pathology and enhance clinical support staffing,” MGB said.

“We begin this work now with the goal of ensuring that MGB Cancer is fully operational using our own resources, ready to serve patients before the conclusion of our current agreement with Dana-Farber in Fall 2028,” Klibanski wrote.

The state Public Health Council on Thursday is slated to vote on a determination of need request from Dana-Farber, which is looking to build its own cancer hospital with Beth Israel Deaconess Medical Center.

MGB Cancer plans to “extensively” renovate three floors at the Brigham’s Hale Building for Transformative Medicine in the Longwood area to support outpatient clinical space, plus one floor at Faulkner Hospital in Jamaica Plain, Klibanski said. MGB is also looking to relocate clinical, office and research space in the Longwood area, which the system said is “currently housed mainly at the Dana-Farber Cancer Institute.”

In other efforts to bulk up oncology services, work is underway at Massachusetts General Hospital, where a new tower is expected to provide “large-scale new resources for MGB Cancer patients,” Klibanski said. The system is also working on a new exam room and infusion capacity at MGH-Waltham.

“Our goal is to immediately begin to execute on our cancer strategy and provide space for both our existing and new cancer teams to work, perform research and care for patients,” Kevin Giordano, MGB’s senior vice president of operations, said in an internal article shared with the News Service.