A few weeks after Nancy G. Brinker completed chemotherapy for breast cancer, she got back on her horse and rode in a polo tournament with a pink helmet on her bald head and pink socks on her pony.

Though a small bruise caused her arm to swell up with lymphedema “like an elephant’s leg,” Brinker, who was then 37, says she “stayed true to the woman I was before I had cancer. If it comes down to a choice between risking and settling, I’ll take the risk.”

That personal victory, fueled by ramrod determination, defines Brinker, 64, founder and chief executive officer of Susan G. Komen for the Cure. Established in 1982 with $200 in a shoebox and a list of friends, the foundation has not only raised $1.5 billion for breast cancer awareness and research, but has all but erased the silence surrounding the illness. In Brinker’s words, it has “turned a charity into a movement.”

The story behind the organization’s founding is almost legendary. Just before Brinker’s sister, Susan G. Komen, died at age 36, she extracted a promise from her sister. Brinker recalls the exchange in her new book, Promise Me: How a Sister’s Love Launched the Global Movement to End Breast Cancer (Broadway). “Breast cancer—we have to talk about it,” she recalls Suzy saying, her voice barely above a whisper. “It has to change…so women know…so they don’t die…. Promise me, Nanny [Brinker’s nickname]. Promise…you’ll make it change.”

“I promise, Suzy,” Brinker replied. “I swear. Even if it takes the rest of my life….”

“In the months after making that promise, Nancy lay awake at night wondering if one person can really make a difference,” explained President Obama when he honored Brinker last year with the Presidential Medal of Freedom, the highest civilian honor in the United States. “Nancy’s life is the answer.”

During the past three decades, Brinker has worked tirelessly for early detection, hope, research and survival. “People thought there was something inherently salacious about the word breast,” she writes. Early on, some husbands forbade their wives to return her phone calls because they didn’t want their names associated with breast cancer, she recalls. Today, a savvy combination of grass-roots activism and corporate support has “democratized” the disease.

The comparative figures from 1982 and 2010 reveal the startling progress the foundation has spurred: Then, less than 30 percent of women received regular mammograms; now, nearly 75 percent do; then, the five-year survival rate when the cancer is caught early was 74 percent; now, it’s 98 percent, with 2.5 million survivors; then, the federal government devoted $30 million annually to breast cancer research, treatment and prevention; now, the number exceeds $900 million.

But for Brinker, the strides are not enough. She points out that 1.3 million people will be diagnosed with breast cancer this year, and 500,000 will die from it. Her ultimate goal is to learn how to prevent the disease (even prenatally), though she realizes she might only get to her “B-level” aim: for breast cancer to become manageable, like diabetes or chronic heart disease. “I was raised in the era of polio,” she says. “The country marshaled all its resources and all but eradicated polio. Maybe breast cancer will have the same chance.”

SGK’s newest international partnership, the Israel Breast Cancer Collaborative, was launched last October in Jerusalem with Hadassah and other partner organizations. It will work to enhance advocacy, awareness, screening and treatment in Israel, which has one of the highest rates of breast cancer worldwide. The walls of the Old City were bathed in pink light as thousands of runners gathered for the Susan G. Komen Israel Race for the Cure on October 28. “The Middle East is the seat of so much tension, yet here’s an issue that cuts across all institutions, races, religions and people,” Brinker says. (She has also “pinked” the Pyramids, the White House and Budapest’s Chain Bridge, reaching 50 countries across the world.)

Race for the Cure generates more than $55 million annually for SGK. Its success has caused Brinker to be known as a pioneer in the field of cause-related marketing. She points out that the phrase was actually coined by American Express in 1983, when the company donated a penny per transaction and a dollar for each new card to the Statue of Liberty restoration project. “I never claimed to have invented [cause-related marketing],” she writes in Promise Me, “but I sure as heck put some gas in its tank and drove it like a roadster.”

Susan Carter Johns, SGK’s strategic relationships vice president, remembers meeting Brinker in 1982, when Johns was a journalist covering Brinker’s first event. “I had to sit down with my editor and figure out how to write the story without using the words breast cancer,” she recalls. She describes Brinker as a “power to be reckoned with…fighting until she gets what’s in the best interest of the people she serves.” Johns quotes Bob Crandall, the former chief executive officer of American Airlines and one of the organization’s founding corporate partners. When asked why he got involved, Crandall replied, “I just got tired of Nancy Brinker coming to my door and asking.”

Johns adds that the scope of Brinker’s contributions reaches far beyond breast cancer. “She has empowered women to have a voice and to be considered important.” Three decades ago, for instance, clinical trials were conducted almost exclusively on diseases that affected men. Breast cancer is often the conduit to beginning a dialogue among women, she says, “but the outcome is much greater.”

Hadassah Lieberman, wife of United States Senator Joseph Lieberman, longtime friend and SGK global ambassador, notes that Brinker “took a very personal feeling and made it into a life’s goal. What’s most striking is how forthright and straight on she’s been in honoring her promise and how constantly dedicated and ambitious she is toward reaching her goals.”

SGK’s symbolic pink ribbon reminds Brinker of her sister’s soft femininity. “She was the ultimate girl’s girl,” says Brinker, who in contrast was bookish, serious and athletic as a teenager. If Suzy’s color was pink, Brinker’s is red. A picture of the two sisters in high school sits on a side table in Brinker’s Georgetown residence, which is decorated in ivory and red. (She also has a house in Palm Beach, bought to be near her parents.) “My father wanted a boy and raised me like one. He involved me in business decisions. Suzy taught me all the feminine stuff. We were really good friends. I still hear her voice and feel her presence.”

Sparks of Brinker’s tomboy spirit merge with her tailored elegance. She wears a copper-hued blouse, black skirt, heavy gold necklace and bracelets—but no stockings. Her perfectly coiffed hair is actually pulled back into a ponytail with well-placed wisps framing her face. She still exercises every day but back problems have made riding impossible. She enjoys reading on her Kindle, especially historical biographies like Mrs. Adams in Winter: A Journey in the Last Days of Napoleon, about Louisa Adams’s solitary 40-day journey from St. Petersburg to Paris in 1815 when husband John Quincy was a diplomat in Prussia.

Brinker identifies with the challenges of being the voice and face of America overseas. She left her post at SGK to serve as United States ambassador to Hungary from 2001 to 2003. Previous visits to Eastern Europe had drawn her to the newborn democracy and carved a deep-felt connection to the “sharp-chiseled men and bold, alto women.” She also hoped to advance the cause of women’s health care there. The date of her departure for Budapest was scheduled: 9/11. She did not leave until a few days later. “It was a lonely first year,” she recalls. “No one came to visit. It became very military, with lots of security.” Her health care agenda simmered on the back burner, but she eventually created the Bridge of Health Alliance Against Breast Cancer in Hungary.

And she fell in love with Hungarian art and began collecting “obsessively…. It’s now a not-so-secret addiction,” she says. Her residence houses her extensive catalogued collection, which has been featured in seven major exhibitions and in partnerships with Art for the Cure, blending art appreciation with breast cancer awareness and fund-raising. The works greet visitors immediately, spill over into the hallways and even the bathroom. In the living room, Bela Czobel’s Reclining Girlcelebrates a woman’s body; Mihaly Munkacsy’s smiling Tin Drum boy depicts the “innocence of youth interrupted by tragic circumstances that change everything,” Brinker notes.

Brinker has come a long way from her hometown of Peoria, Illinois. But one thread remains strongly in place: “The overarching theme of my upbringing was ‘Do the right thing!’” she says. She grew up in a Reform community grounded in the principles of tzedaka and tikkun olam. From her father, Marvin Goodman, a “driven and principled businessman,” she learned “the empowering nature of purpose.” (He died in 2007.) Her mother, Eleanor, now 90, bundled her daughters into the family station wagon every weekend on “various missions,” from organized charity work to “little personal mercies…,” Brinker writes, describing her mother as the “standard bearer, doer of good, righter of wrongs, mitzvah maven.”

After receiving her B.A. from the University of Illinois at Urbana-Champaign, she moved to Dallas. She worked her way up through the marketing and executive development training program at Neiman Marcus; studied broadcast journalism for a year at Southern Methodist University; began her own company offering health products and information; and married and divorced Robert Leitstein, a Neiman Marcus vice president. Their son, Eric, 35, runs the Goodman family real estate business in Peoria and commutes between Illinois and New York. Her second husband, Texas entrepreneur Norman Brinker, whom she married in 1981, encouraged the vision that became SGK.

Though the Brinkers divorced in 2000, their lives remained intertwined; her book testifies eloquently to his impact on her life: “Norman Brinker didn’t create me,” she writes, “but he planted me like a tree.” Norman Brinker passed away in 2009.

Brinker indulged her pragmatic and perfectionist streak as United States chief of protocol (2007 to 2009), planning, hosting and arranging ceremonial events and logistics for visiting heads of state and dignitaries from the Pope to the Dalai Lama. She developed “Experience America” for diplomats to travel the country and meet with business, civic, scientific and technology leaders. She is now back at the helm of SGK—and if she weren’t advocating for that cause, she says, she would have found another. “All I ever wanted was to lead a life of meaning,” she acknowledges.

Though Brinker recognizes her achievements, her life and work continue to revolve around her sister. “Our story is like that of Ruth and Naomi,” she says. “I won’t ever leave her or forget what I have to do.”