ANN ARBOR, Mich. -

Becky Dykes just turned 29.  It's a birthday she feared she might not live to see. 

The single mom from White Lake, Mich. is fighting a very rare cancer. 

"If the cancer takes me, what's going to happen for my daughter?  That's really the first thing that popped into my head," said Dykes.

It's a question no parent wants to consider, but it's one Dykes and her young daughter Vanessa can't avoid.

"She had her little fingers crossed, and my mom asked her why she was crossing her fingers and she said, 'I'm just hoping that Mommy doesn't die,'" said Dykes.  "Of course, you want to tell her everything is going to be okay, but at the same time, I don't want to give her false hope."

But hope is something Dykes has a little more of lately, thanks to her doctors at the University of Michigan.

Her strange symptoms first started three years ago, shortly after she moved to Georgia.

"An insane amount of itching.  I'd just be itchy all the time," said Dykes.

Doctors initially thought the itchy patches on her face and scalp were due to an allergy, but while visiting her family in Michigan this past Christmas, Dykes started to get much worse.

"Very lethargic, sleeping all day.  I couldn't stay up for more than three hours at a time," said Dykes.

A chest X-ray revealed the stunning truth.

"All my lymph nodes were enlarged, and from that point we went forward, and they found the cancer," said Dykes.

She was diagnosed with stage 4 histiocytic sarcoma.  It's an extremely rare cancer that involves a specific type of white blood cell called a histiocyte.

"It is something that we see very, very rarely even in a major cancer center like the University of Michigan.  I had never seen one before," said Dr. Ivan Maillard, a hematologist and researcher at the University of Michigan's Life Sciences Institute.

Only about 200 people in the world have been diagnosed with the type of cancer Dykes has.  That doesn't give doctors much guidance when it comes to treatment, but from the start, Dykes' team was determined to find a way to help her fight.

"We started with conventional potent chemotherapy, and she had really no response to that whatsoever," said Maillard.

By then, the cancer had spread to Dykes' spleen, liver and chest.

"There was two weeks that she was on her death bed.  We didn't expect her to make it through the night," said Judy Trahey, Dykes' mother.  "She was literally suffocating."

That's when her doctors made a big discovery.

"We noticed that her cancer cells were expressing an unusual protein for which we have a drug that can target it very very specifically," said Maillard.  "We reasoned that even if it had never been tried before, if the target was there, the drug that we had against that target might be effective."

Dykes is the first patient with her cancer to be treated with the drug called brentuximab.

"It was a little bit of a miracle," said Maillard.  "Virtually within 48 hours after we gave her the drug, everything turned around.  She felt subjectively better, and all of the parameters that we could measure in her blood and otherwise were starting to improve.  We could see her spleen shrinking from week to week, and all her blood counts became normal."

"Just the knowledge that the doctors have that they'd even try this is awesome, it really is," said Dykes.

Doctors have also worked with the manufacturer to make sure the cost of the treatments is covered.  It's around $25,000 a treatment, every three weeks.

What doctors have learned from Dykes could help other patients battling this cancer and others.