Chiara D'Agostino was scheduled to have an infusion of immunotherapy today, her fourth round in a fight against an aggressive form of breast cancer.

Instead, she asked her doctors to move up her appointment so she could make it to a special occasion: The last public speech by the woman who is leading the charge to keep Obamacare.

Health and Human Services Secretary Sylvia Burwell will be making a last-minute sales pitch for retaining Obamacare - the landmark law that faces evisceration under the new administration.

The speech is at the National Press Club in Washington D.C., and at her side will be D'Agostino and two other women whose life stories reflect the law's impact.

D'Agostino met Burwell at the Tops Diner in East Newark last month, part of a whistle-stop campaign by Burwell to encourage people to enroll in the government-sponsored health insurance marketplace.

D'Agostino had posted about her gratitude for the Affordable Care Act on Facebook, saying that without the Medicaid coverage it brought, she'd probably be dead. That post came to the attention of Burwell staffers, who extended the invite.

The Tops Diner meeting came just days after D'Agostino's double mastectomy, undertaken after her cancer reappeared. She's now receiving immunotherapy at the Rutgers Cancer Institute of New Jersey.

D'Agostino enrolled in Medicaid in September of 2014, at the very start of the Affordable Care Act's first year. The 45-year-old Montclair resident, a former high school Italian teacher, had just returned from studying abroad and needed insurance coverage while she looked for a job.

She found a lump in her breast the very next month.

With Obamacare now on the chopping block of the new Congress, D'Agostino felt the issue was important enough to alter her treatment schedule to tell her story.

"I thought, 'I've been having a hard time with holidays, and just having those recent surgeries and having metastatic cancer, this would be a fun opportunity to let my voice be heard and help others," she said. "It's something that I'm passionate about anyway. It's an honor."

The speech will be live-streamed here.

Reporter: Kathleen O'Brien