Identical mirror twins get nearly identical breast cancer diagnoses within weeks of each other

SAN FRANCISCO -- Like so many twins, Hanna Thompson and Metta Siebert grew up doing everything together.

In 2008, when Thompson won a silver medal for fencing at the Beijing Olympics, her sister was the loudest person there cheering her on.

"We were more or less attached at the hip," Thompson told ABC7 from her apartment in San Francisco. "We even went to the same college together."

Now, at 35-years-old, Thompson lives in San Francisco and Siebert in Kansas City. Despite the 2,000 mile difference, they're more connected than ever.

The sisters were both recently diagnosed with breast cancer. Their dual-diagnoses came within just three weeks of each other.

"To say it was a one-two-punch was an understatement," Siebert said over Facetime.

"We're like the super special identical twins and we're clearly taking that way too far," Thompson added.

Siebert and Thompson are identical mirror twins, which means one is left-handed and the other right-handed; one has a stronger left eye, the other a stronger right eye.

Their cancer is a mirror image, too.

"For masses, she actually has the mass on her left side. I have it on the right side," Thompson said.

Both sisters learned that they have the BRCA2 gene mutation, which gives them a 70-percent chance of getting breast cancer in their lifetime.

"This is very young, but this is what we see with a BRCA mutation," Dr. Pamela Munster, who is a leading oncologist at UCSF specializing in breast cancer and the co-leader of the Center for BRCA Research, told ABC7 News.

Dr. Munster said it's not uncommon for identical twins to get similar breast cancer diagnoses. The timing, however, is unique.

"Maybe this has all been an opportunity because one of the twins that was diagnosed can now tell the other one to get tested, and hopefully we can detect the tumor much sooner," Dr. Munster said. "I think one twin was lucky to have another twin and I think most twins would think they're lucky to have another twin anyway."

Thompson, who is a patient at UCSF, and Siebert said they wish they had been tested for BRCA earlier.

"I just wish I knew a little bit more about that because it could have changed our treatment a little bit," Siebert explained.

Over the past two months, the sisters have seen an outpouring of support for friends, family and their fencing community. Nearly $25,000 has been raised on their GoFundMe to help with medical costs - something for which they said they are incredibly grateful.

But more than anything-- like always-- they have each other.

"Not that I would wish it upon her," Siebert said, "But it maybe makes it a teeny bit easier."

Thompson agrees.

"There's no other person I'd rather be going through it with than my twin sister," she said.