DENVER -- It was only a few years ago, that doctors found out screening and early detection made a difference in treating breast cancer patients. Now the University of Colorado Cancer Center is conducting a trial to see if that's the case for prostate, lung, colorectal, and ovarian (PLCO) cancer patients.

"It sounds like that if you find a cancer early and treat it, that you'll impact somebody's outcome, but that may not be the case in all cancers," said UCCC's Dr. David Crawford.

The PLCO Screening trial randomly follows volunteers, usually between the ages of 55-74, to see if screening will reduce the number of those who die from these specific cancers.

Frank Meogrossi is one of the thousands of volunteers in the trial.

"My mother died of cancer when she was about 62 and my brother approximately five years ago had prostate cancer," said Meogrossi.

Meogrossi enrolled in the PLCO screening trial in 1997. He was 57 years old at the time. Ironically, during the trial, he was diagnosed with prostate cancer.

"You always hope it won't happen, but you have it at the back of your mind," said Meogrossi.

For Meogrossi, he said the screening and early detection made a difference. He has since had surgery and doctors said he should be cleared. But that might not be the case for other cancer patients.

"For instance in lung cancer, years ago, it was thought chest x-rays would be helpful. In fact, it wasn't. Now we're doing a study with CT scans to see if that matters. Again we don't know," said Dr. Crawford.

That's what reseachers with the PLCO trial hope to find out. Already, doctors are using the information they've collected from the trials so far. PLCO is expected to wrap up in September 2011.

"The downside may be that you have a lot of people who are subjected to invasive tests and biopsies that may do more harm than good and really not alter the outcome in cancer in the long run," said Crawford.

Crawford added that in order to move forward in the fight against cancer, researchers have to compare one treatment to another to see what works best and will help patients in the long run.

For more information on the PLCO screening trial, go to parplco.org.