Henda Salmeron is not a large woman. A slight, angular brunette, she’s the kind of woman who upsets other women when she says she needs to lose weight.

When she turned 42, Salmeron decided that’s exactly what she needed to do. A few extra pounds had stacked up thanks to stress and lack of exercise. So she left her Lakewood home and headed for White Rock Lake. During the spring of 2009, the South Africa native learned to scull. Between February and April, she lost 12 pounds.

Those 12 pounds, she says now, probably saved her life. That’s an understatement. Those 12 pounds most likely saved the lives of hundreds, if not thousands, of women. Those 12 pounds may be 12 of the most important pounds in the history of women’s health in Texas. They led to Henda’s Law.

After Salmeron lost the weight, she noticed a lump, about the size of a pea, near her right breastbone. Mammograms at age 35, 40, 41, and 42 were normal, but Salmeron couldn’t let it go.

“My mother-in-law said, ‘Henda, no lump is nothing. Don’t let them tell you it’s nothing. Go get it checked again,’ ” she says. “And you know what? It was probably the single best advice I’ve gotten in my life.”

Salmeron had another mammogram, which also showed nothing. But the BB-size bump on her chest wouldn’t let her drop it. A sonogram was the next step. The sonogram revealed a shadow, a shadow big enough to maybe mask cancer. The shadow led to a needle biopsy, which led to Sunday, June 7, 2009, at 8:35 am. Salmeron—a senior vice president at Ellen Terry Realtors—was on her way to write a contract for a $900,000 home in Preston Hollow when she got the call. Her gynecologist was on the line. They had found cancer in her right breast.

What followed was the most surreal afternoon of Salmeron’s 42 years. She helped a couple—not even her own clients—write a contract on their house, then headed to her daughter Dominique’s ballet recital at SMU. Apart from Dominique’s brief appearance on stage, Salmeron spent the entire afternoon pacing the terrace at McFarlin Auditorium, the cancer altering her world’s spin.

By Monday afternoon, Salmeron was under the care of Dr. Roshni Rao, a surgical oncologist at UT Southwestern. By Tuesday afternoon, she got the worst phone call of her life, less than two days after receiving her previous worst call.

Instead of the 1-centimeter lump found by the sonogram, Salmeron’s was 4 centimeters, invasive and advanced.

“I was like, ‘F---, what?’ You’re dazed and confused already, and now you hear, in my case, it was far more of a death sentence than I heard two days ago. I was afraid. I was afraid I would not see my kids graduate from elementary school.”

Later that day, Salmeron found herself in a waiting room at UT Southwestern, surrounded by grandmothers in Pepto-Bismol-pink hospital gowns. Ten, 20, 30 years separated her from her comrades. How did she pull this card?

Her thoughts quickly turned to her mammograms, the ones that showed clear. Looking at them, anyone would have a hard time finding a lump or tumor. They look like a photo from space of clouds passing over Earth; the whitish muscle quickly transitions into black and gray fat.

The reason the cancer wasn’t diagnosed at a smaller size, Rao says, was dense breast tissue. A condition that affects more than half of women younger than 50, and one-third of women older than 50, dense breast tissue can mask small lumps or tumors, as the tissue appears as the same color on mammograms as lumps: white. Breasts with a higher percentage of tissue than fat are considered dense.

“It’s like a snowball in a blizzard,” Salmeron says.

Women with dense breast tissue are not only at a higher risk of a hidden tumor, they are also at a higher risk for tumors in general. A 2007 New England Journal of Medicine study showed women with dense breast tissue are four to six times as likely to develop breast cancer as those with regular breast density.

“Henda was not happy, understandably,” Rao says. “And women like her are angry. They feel like they are doing all the right things, and they’re still in this position.”

For those wondering, no, you can’t feel breast density by hand. The firmest breast could be the fattiest breast. As women age, their breasts naturally become less dense, making mammograms more accurate, Rao says. There’s less tissue to mask problems.

According to the American Medical Association, mammograms may miss up to 40 percent of tumors in women with dense breast tissue, and Salmeron had never even heard of the condition. The phrase never even grazed her vernacular.

That was the most inexcusable part of the whole situation. After having years of mammograms, no single doctor had told her she had dense tissue.

She was angry. But out of that anger grew advocacy.