After Frank DePaola, the general manager of the MBTA, was diagnosed with cancer right before the winter of 2015, slowing down wasn’t an option.

When record-breaking winter storms blanketed the region during that time, DePaola was in charge of making sure the highways were properly cleaned for commuters. At the time, DePaola was the state’s highway administrator and had recently stepped into the newly created role of chief operating officer of the Massachusetts Department of Transportation.

But even when Transportation Secretary Stephanie Pollack approached him months later about heading up the embattled Massachusetts Bay Transportation Authority, DePaola’s diagnosis didn’t stop him from stepping up again. He took over in March 2015 after Beverly Scott stepped down.

“It was a pretty quick decision,’’ DePaola told reporters on Wednesday. “It was an easy decision to make because I have a lot of friends at both the MBTA and the [Department of Transportation], and I wanted to make sure that they succeeded.’’

DePaola last week announced he is leaving the agency on June 30 to focus on the prostate cancer that he has been battling for more than a year. Brian Shortsleeve, the agency’s chief administrator, will take over the post temporarily after he leaves.

“I think I’ve left my stamp on this agency, and it’s time to move on,’’ DePaola said. “If my health was better, I’d love to stay on, but at this point, it’s time for me to make sure my personal health is addressed.’’

The Brockton native chose to keep his diagnosis secret from many of his colleagues for much of 2015. That’s the year he dove head-first into the controversy engulfing the T and its commuter rail system, which had earned the ire of thousands of stranded and frustrated commuters during the winter.

Among his achievements: executing a winter resiliency plan that would help the agency avoid disastrous winters.

But before snow could hit the ground and the new plan could be tested, doctors told DePaola in the fall of 2015 he would have to get surgery as a part of his treatment. Worried about being out of commission during the winter, however, he asked doctors if he could wait until the spring.

After getting his doctors’ blessing to hold off on the procedure, DePaola told Pollack and others about his cancer. Pollack was concerned he was jeopardizing his health, he said, but he assured her it wouldn’t be a problem.

“I did tell Frank if that there was any reason that he really shouldn’t wait and that he should do the surgery in the winter, that we would figure out how to run the T in the winter without him,’’ said Pollack, who sent out a memo last week praising DePaola. “I do think the fact that he chose to postpone the surgery is indicative of Frank’s commitment and loyalty to the job and the organization,’’ she said.

DePaola has also had to grapple with other controversial issues during his time at the agency: The Green Line extension was halted for nearly a year amid concerns about budget overruns, and the agency chose to hike fares and cancel late-night service on the weekends.

He says the biggest issue the T will face after he leaves is seamlessly getting new Red and Orange line cars into service.

DePaola said he plans to retire after June but knows he’ll have to find something else to do. When he was out for more than two weeks for surgery recently, he found himself bored.

“The silence was driving me crazy,’’ said DePaola, who usually works a 12-hour day and gets to the office by 6 a.m.

He won’t have to worry about that this summer. During Wednesday’s fiscal control board meeting, it was clear that he’ll have his hands full before he leaves in a little more than a month.

“And trust me,’’ Pollack joked, after officials praised him for his service. “He has a really long to-do list before he’s allowed to go.’’

Nicole Dungca can be reached at nicole.dungca@globe.com. Follow her on Twitter @ndungca.