A 29-year-old woman felt a lump in her breast, but her ultrasound was clear. She now has stage 4 cancer.

• Kristine Stone found a breast lump at age 29. She was given ultrasounds, but denied mammograms.
• Six months later, she was diagnosed with stage 4 breast cancer.

By age 29, Kristine Stone had earned her MBA and worked her way up to a senior business analyst position at a nonprofit in Seattle. "I was doing my dream work, my end-goal stuff," Stone, now 38, told Insider.

Then, she felt a lump in her right breast. Her grandmother had just undergone chemotherapy for breast cancer, so getting it checked out promptly was top of mind.

But Stone said clinicians at the local hospital said she'd need to get an ultrasound first, and that test didn't detect any problems. "There's nothing to worry about," Stone said the doctor told her, and then denied her second request for a mammogram.

Stone sought a second opinion. The response was the same. "No one would refer me to a mammogram," she said.

Clinicians were, in fact, following guidelines: According to the American College of Radiology Appropriateness Criteria, it's "usually not appropriate" to conduct a mammogram on a woman under 30 with a breast mass if ultrasound findings are benign.

But Stone is now challenging such policies: Six months after her initial ultrasounds, she was diagnosed with stage 4 breast cancer that spread to her lymph nodes and bones. By then, her lump was more noticeable, her right arm and hand had gone numb, and her armpit was "super sore," Stone said.

When clinicians told her it was cancer, Stone said she thought, "No shit. I told you that six months ago. Now how do we get it out of here?"

Stone is now a full-time patient

Stone underwent about nine months of chemotherapy. Then, more imaging revealed the cancer had spread to her brain. Doctors were able to cut it out, but the procedure has left her with short-term memory loss.

These days, she undergoes immunotherapy treatments every three weeks that leave her exhausted. She also has arthritis from the cancer and treatments. Stone can no longer work or drive, struggles to read, and hasn't had a vacation "in years and years." She lives in an apartment beneath her dad and stepmom in Renton, Washington.

Stone tries to find comfort in sewing port pillows for cancer patients, oil painting, and advocating for more thorough testing in young women who notice a change in their breast tissue.

"I hope younger people will be more alert and aware, but more than anything, I hope the policies and the doctors will change," she said. "No one should have to go through this, and had they done a mammogram at 29, then I believe they would have seen the cancer."

Stone said her current doctor said she may be able to stop treatments this fall if testing reveals no evidence of disease. If that's the case, Stone — a former hair stylist — thinks she might want to volunteer to cut hair for others going through or recovering from cancer.

"I would love to be able to help other cancer patients," she said. "But at the same time, I'm also sick and tired of cancer."

Ultrasounds tend to be more accurate than mammograms in younger women

Breast cancer is most common in women over 50, but about 9% of all new cases in the US are found in women under 45, according to the Centers for Disease Control and Prevention.

Dr. Laurie Margolies, chief of Mount Sinai Health System's breast imaging center, told Insider that ultrasounds are the go-to test for most women under 30 in part because younger women tend to have denser breast tissue, and ultrasounds tend to be better at detecting a lump's cause in such tissue.

With ultrasound in young patients, "most often, a benign cause can be readily found, and no further workup is needed," she added. "Very often, the pain or the lump goes away and everything is fine."

Mammography also isn't recommended as the first test for young women with a higher risk of breast cancer due something like family history or a genetic mutation, Margolies said. Rather, most of them should get a breast MRI, which also tends to be more accurate in dense breasts.

"Mammography is wonderful and finds many cancers and has been proven to reduce morbidity and mortality from breast cancer by 40% in multiple studies, and is clearly the right first test for the majority of women over age 40 that are at normal risk," Margolies said. "But for many women, it's not enough."

Seek a clinician with expertise in breast ultrasound

In the cases of women under 30 wishing they'd gotten mammograms earlier, Margolies said, "it's very likely that the mammogram would not have added anything" to the ultrasounds' results.

What can make a difference, though, is how your ultrasound is interpreted. The scans don't come back with clear "cancer" or "no cancer" signals, and different clinicians can have different takes on what the image means.

"Breast ultrasound is extremely nuanced and extremely operator-dependent," Margolies said. "It's not always so easy to determine if something is a simple cyst versus, for example, a triple-negative breast cancer. It can be extremely difficult to make that distinction."

She encourages young women who are concerned about a change in their breast tissue go to a facility that the American College of Radiology has accredited for breast ultrasound. And, ask questions: Does this center do a lot of breast ultrasounds? Are the radiologists who read the ultrasounds breast imaging specialists?

"And then listen to your body," Margolies said. "If it's persistent or if it feels very hard or if it's growing, go back. Don't be embarrassed about going back and asking more questions."