After losing her right leg in 1972 to osteosarcoma, a type of bone cancer, Connie Mielich had years of cancer-free living. But she had a recurrence of the disease several years ago, this time in her chest.

When the cancer appeared for a third time last year, she turned to an option that relatively few cancer patients pursue: She enrolled in a clinical trial, a study to test new drugs or procedures.

Mrs. Mielich, 57, of Tylersport, Montgomery County, was in Pittsburgh this week on behalf of the American Association for Cancer Research to promote participation in clinical trials.

The association is a scientific adviser to "Stand Up to Cancer," a nationally televised fund-raising event that will air simultaneously on ABC, CBS and NBC tonight at 8 p.m.

While more funds for research are needed, progress also requires more participation in clinical trials, said Gwen Darien, the association's director for survivor and patient advocacy.

Testing new drugs or other therapies often takes years. The biggest barrier to completing the studies is that not enough people participate, according to the American Cancer Society. Nationally, fewer than 5 percent of adults with cancer will take part in clinical trials.

The main reason people give for not participating is that they didn't know the studies were an option for them, the society said.

While most cancer patients are not treated at academic medical centers, access to clinical trials has become much more available, said Dr. Barry Lembersky, an associate professor at the University of Pittsburgh Cancer Institute.

Still, some patients are reluctant to participate, he said. They may not be comfortable, for example, with being a subject in a study. Others may not be eligible, or may not need to consider the option because the standard therapy is so good, Dr. Lembersky said.

But cancer patients should at least consider the option "at all decision points in their care," he said.

There are several types of trials. Phase II trials, for example, generally test the effectiveness of new treatments, while Phase III trials compare the treatment to standard therapy.

Patients who participate in the trials may or may not get the treatment being tested. But they will at least get the standard therapy. Dr. Lembersky said.

Phase I trials, an earlier stage of testing, assess the safety of those drugs. They are generally used with patients who have exhausted standard treatment options, he said.

Both doctors said that participating in a trial may provide patients with better treatment and will help researchers develop better ways of diagnosing and treating cancer.

Patients should ask their oncologists about clinical trial options, Dr. Lembersky said. They also can seek second opinions or consult other sources. For example, information is available from the American Cancer Society at 1-800-ACS-2345 or www.cancer.org.

Though Mrs. Mielich also had endometrial cancer in 1994, she said she never expected her original cancer to return so long after her initial diagnosis. But doctors had told her that if it returned, it would likely do so in her lungs. After doctors found in 2005 that the cancer had recurred in her right lung, the lung was removed. Last year, the cancer returned again in the same area of the chest.

Mrs. Mielich said the medication she received as part of the clinical trial helped shrink two tumors by about 50 percent. But they eventually began growing, making her recently ineligible for that trial. She hopes to participate in another trial and have good results.

She said her faith in God has helped her live with the disease, as well as "living each day as if it's your last."