Amanda Petersen, 39, stood outside the Capitol in a dark blazer and bright red lipstick, khaki pants tucked into her black sneakers. It was still early enough in the morning that only a few tour buses were idling outside. The West Virginia native was wide-awake as joggers and dog walkers zoomed by. Were it not for her bald head, it would be difficult to tell that she has stage IV breast cancer."In my brain, I feel like a young person. But my body feels like an old person’s," Petersen said. "It’s hard for me when people tell me, 'You’ll be fine, you’ll be fine.' It’s hard for me to say, 'But I won’t.'"On Thursday, Petersen and about 200 other survivors and family members marched from the Washington Monument to Capitol Hill as part of nonprofit organization METAvivor's Stage IV Stampede . Lying on the grass in front of the Capitol, they staged a "die-in," ringing a bell 113 times to symbolize the number of people who die from metastatic breast cancer — the kind Petersen has — every day in the United States.An estimated 40,450 people are expected to die of breast cancer in 2016, according to the American Cancer Association. And although it's often left out of the pink-ribbon-filled awareness campaigns, stage IV (known as metastatic) breast cancer is what causes nearly all breast cancer deaths . Around 30% of women and men who get breast cancer will have it metastasize to other parts of their body, according to METAvivor After being diagnosed with stage II breast cancer when she was 34, Petersen underwent two mastectomies, chemotherapy, and another year of targeted treatment. "I was quote-unquote cancer free," she said. She was excited to get on with her life, and she and her husband applied to become foster parents."Just as we were about to finish that process, I landed in the hospital with a fractured vertebrae. I found out through the MRI that the cancer had spread to my bones, to my liver, and to one of my lungs," she said. "It was like I went from a 38-year-old person to a 78-year-old person overnight."Now, with the cancer also in her brain, Petersen said she has accepted that she is going to die. But she wants to do everything she can to make sure others don't have to go through what she has.Ahead, Petersen and other survivors share their stories of living with stage IV, losing loved ones, and their fight for research funding with Refinery29.