By July, Steinbeck had been diagnosed with stage 2 breast cancer, two days before her 30th birthday.
About 27,000 women age 45 and younger are diagnosed with invasive breast cancer annually, making up about 12 percent of the total women diagnosed, according to the American Cancer Society. Approximately half those women are postpartum, defined as having given birth within the past five years.
Virginia Borges, Steinbeck's oncologist, wants to know why.
Borges is overseeing a unique, ongoing study of healthy mothers at the Young Women's Breast Cancer Translational Program, which she directs at the University of Colorado Cancer Center.
Looking for risk factors, "we've asked young women who recently gave birth, after they're done nursing or if they decided not to nurse, to come in for a one-time breast biopsy," Borges says. "These are women who have never been affected by breast cancer, so that we can see what normally goes on in breast tissue."
The center has been overwhelmed by the response.
"The idea of asking a young, healthy woman to come in and give a breast biopsy was a little out there, but I can tell you, these women came out in droves," Borges says. "We've had 90 women already in a six-month period. Women have understood what their peers have been going through."
'Terrible ramifications' • Borges says her goal is "better outcomes" for young women who are at a higher risk for what are often more aggressive tumors.
In addition, postpartum women are three times more likely to experience a recurrence than those who are outside that five-year window.
"Losing anyone to cancer is a terrible thing," Borges says. "Losing a young mom to breast cancer has terrible ramifications on that family."
The Young Women's program, founded in 2005 by Borges and co-director Pepper Schedin, specializes in the treatment and prevention of breast cancer in women under age 45, with an emphasis on pregnancy-related breast cancer.
"Obviously, women can't stop giving birth," Borges says. "Having children is a part of life. But millions of women give birth every year, and a percentage of them are getting breast cancer, so why? How can we better identify who will be those women?"
Some risk factors for young women already are known, including a family history of breast cancer (having a first-degree relative, such as mother, sister or daughter) or carrying the gene mutations BRCA1 and BRCA2. Undergoing the $3,000 test for those mutations is usually recommended only if a woman has a family history.
Citing recent research that points to a link between 20 percent of cancers and obesity and excess weight, Borges also counsels her patients to drop extra pounds.
"I harass my patients to exercise, actually," she says. "If we all had ideal body masses in the normal range, a significant amount of breast cancer would go away."
'Angel baby' • The first time Steinbeck felt the pain in her breast, "it was sort of like mastitis, a cyclical or burning pain," she remembers. "This time, I thought it was a clogged duct. I got some cream, put it on it, and the doc said, 'I'll see you back in a couple of months.'
"With no family history, and I'm so young, it just wasn't alarming to anyone," Steinbeck says.
She found Borges during her search for a second opinion. Without the pain returning after her third pregnancy, "I don't know what would have happened, when I would have realized."
She calls her third child "angel baby." She adds: "One of my doctors has even said, 'That baby probably saved your life.' "
Steinbeck started her first of six rounds of chemotherapy Sept. 16. She grew up playing competitive sports and has never had weight issues, but she has found the center's "Fighting Cancer with a Fork" nutrition program helpful.
"I was never a big fish-eater," she says. "I've been working hard at making sure the whole family doesn't eat things with carcinogens in them and increasing the antioxidant foods, and eating tons of things like broccoli and red peppers, grapefruit, a cup of something red a day."
Steinbeck also is participating in several studies at the center.
"I would do just about anything I can do that doesn't hurt me to help make sure other women don't have to go through this," Steinbeck says. "Imagine if my baby girl didn't have to deal with any of it."