DALLAS (AP) — As her sister was dying from breast cancer, Nancy G. Brinker made a promise to her: She would do everything she could to end the disease.

Brinker fulfilled that solemn commitment by founding a breast cancer charity in 1982 that grew into the world’s largest — a national fundraising powerhouse that has invested $780 million in research and $1.3 billion in services such as screening and education over the last three decades.

Now Brinker, the public face of Susan G. Komen for the Cure, is stepping down as CEO, about six months after the organization’s hotly debated decision to end funding for breast screenings through Planned Parenthood. The move was quickly reversed after an onslaught of criticism but ended up stirring anger on both sides of the abortion debate.

Brinker, 65, will move to a new role focusing on fundraising and strategic planning.

‘‘She’s wanting now to kind of get away from the day-to-day operation as CEO,’’ said Komen spokeswoman Andrea Rader. She said Brinker will concentrate on ‘‘growing the global work, working on the strategy and of course raising the funds,’’ and she will still have ‘‘a major role in the organization.’’

On Wednesday, the group also announced that Komen President Liz Thompson will step down next month, and two board members are leaving as well.

They are just the latest departures. After the Planned Parenthood episode, at least a half-dozen other high-ranking executives resigned, and organizers of many Race for the Cure events — the group’s signature fundraiser — have seen participation decline.

Rader said neither Thompson nor Brinker was available to answer questions Thursday. But she insisted their moves were not the result of the Planned Parenthood decision, noting that Brinker has only served as CEO since 2009 and wanted a different focus.

Thompson, she said, had been thinking of making a change for a while but had agreed to stay on until the controversy died down.

Among those who publicly opposed cutting off Planned Parenthood were some Komen affiliates, including the one for Oregon and southwest Washington, which saw its chief executive resign in the aftermath. The group issued a statement saying it views this week’s leadership changes as ‘‘part of the process of moving past the distraction of earlier this year.’’

Since February, ‘‘supporters have expressed disappointment but also tremendous resolve and a renewed determination,’’ said Devon Downeysmith, an assistant manager for the affiliate. ‘‘The silver lining is that we've really been able to reinforce what our mission is, how we save lives and how we provide critical care.’’

Downeysmith said the organization was grateful for all that Brinker had done and ‘‘how she’s turned the promise to her sister into a global movement.’’

Komen has said the decision to pull Planned Parenthood funding for breast screenings came from newly adopted criteria barring grants to organizations under investigation. At the time, Planned Parenthood was the focus of an inquiry by a Republican congressman acting with encouragement from anti-abortion activists.

After Komen’s decision was made public, much of the anger focused on Komen policy chief Karen Handel, who had opposed abortion as a Republican candidate for Georgia governor. After Komen decided to restore the funding, Handel resigned and said she stood by the decision to pull funding.

In a statement accepting Handel’s resignation, Brinker said the organization had ‘‘made mistakes in how we have handled recent decisions and take full accountability for what has resulted.’’

Handel said the discussion had started before she arrived there last year because the charity was concerned that some Roman Catholic dioceses had encouraged believers not to give to Komen because it supported Planned Parenthood.

The Komen organization started as a small gathering in Brinker’s living room. Brinker herself was diagnosed with breast cancer in 1984 and helped change breast cancer from a taboo subject to a public cause that drew women into the streets to raise money, many of them dressed in the group’s signature pink.

Brinker and her sister grew up in Peoria, Ill. By the late 1970s, Brinker was living in Dallas, part of the executive training program at luxury retailer Neiman Marcus. Komen, who was three years older, was raising her family in Peoria, working as a part-time model.

After her sister’s death in 1980, Brinker knew she had work to do.