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Ovarian, breast cancers: New, targeted therapy

A clinical trial of a drug treating advanced stages of breast and ovarian cancer, is showing great promise. It's targeted therapy for women who are genetically predisposed to the disease -- women who carry the BRCA gene mutations (also known as "bracca" gene mutations). The drug aims at only the cancerous cells, without the toxic effects of chemotherapy.

One woman who's experiencing a startling turnaround, Tina Roark, recently spoke to CBS News correspondent Bill Whitaker.

Roark now describes herself as a cancer survivor.

"This time last year, I wouldn't have ever thought I'd be sitting here today," Roark said.

Roark has been battling breast cancer since 1999. She was just 37 when she was diagnosed.

"My son was in the first grade and he graduated this year," Roark said. "And I did not think I was going to get to see it."

Surgery and grueling chemotherapy led to remission, but five years later, the cancer came back -- with a vengeance.

"I had a lot on my spine, in my bones and my back," Roark said.

Roark is one of the five-to-10 percent of women with breast or ovarian cancers who carry mutations of the BRCA gene. The BRCA 1 and BRCA 2 genes are actually tumor suppressors. So a damaged gene puts women at high risk for the disease. Not only did Roark test positive for the mutation, so did nearly every woman in her family. Cancer struck nine relatives over four generations.

Roark says she was prepared to die. "My life was not worth living, because it was just constant pain and agony and doctors," she said.

When chemotherapy was no longer working, Roark's doctor learned about a drug trial at Cedars-Sinai Medical Center in Los Angeles for end-stage cancer patients genetically predisposed to the disease.

She joined the study in March, under the direction of Dr. William Audeh.

Roark takes 16 pills of Olaparib a day. Here's how the drug works: Throughout the body, cells are constantly replicating and repairing themselves. Cancer cells replicate so fast that mistakes occur, causing DNA damage. Olaparib targets only the cancer cells and blocks the enzyme they need to repair their DNA. The result: the cancer cells die.

In this international trial of around 300 patients, 30 to 40 percent are responding.

"It's very difficult to say 'cure' with anybody who has advanced cancer," Audeh said.

But remarkably, in the past nine months, Roark's tumors have shrunk 64 percent.

"It's always amazing to see a drug that really doesn't have a lot of side effects produce responses in people who have very advanced cancers," Audeh said.

Roark travels from Arkansas every month, and nervously awaits test results.

When examining her, Audeh told Roark "everything's stable." He added, "It's very hard to find any cancer on your scans or any sign of it in your blood."

"Wow," Roark said.

"So we will just keep going," Audeh said.

"All right, that sounds good," Roark said. "... It's amazing, every day is wonderful, it's a Godsend; it's a blessing."

And now, Roark is looking forward to her son's next milestone.

When asked what it was like to see her son graduate, Roark said, "It was a beautiful day. Now I'm going wait and see him graduate college. I'm going to see him walk across that stage."

And some time next year, about 100 more patients will be accepted into the trial.

In the battle against cancer, "Early Show" co-anchor Erica Hill noted, the future lies in targeted therapy -- identifying and understanding which genetic mutation has occurred and finding a drug that disables the cancer cells while leaving healthy cells alone. While these results are encouraging, the study is still trying to ascertain just how long this drug will continue to be effective against the disease.