Scattered Clouds88° WeatherScattered Clouds88° Weather

Researchers hunt for reliable early-detection test for lung cancer

A digital chest X-ray of a woman shows a large tumor in the left lung. Below, these charts show the top five cancer killers, and the number of deaths per 100,000 Americans, according to the American Cancer Society.

iStockphoto.com

A digital chest X-ray of a woman shows a large tumor in the left lung. Below, these charts show the top five cancer killers, and the number of deaths per 100,000 Americans, according to the American Cancer Society.

It takes more lives in a year than colon, breast, liver, kidney, melanoma and prostate cancers combined. Yet there is still no definitive screening test to detect lung cancer early, when tumors are at their smallest and before the cancer has spread.

Scientists already know that chest X-rays and sputum tests don't work well for early detection. Doctors are awaiting results from a huge National Cancer Institute study to find out whether the answer might be spiral CT scans, in which images are made all around the patient's body, allowing a 3-D model of the lungs to be constructed.

But, so far, nothing has been proven to find lung cancer early enough to save a significant number of lives, the measure by which most medical screening tests are judged to be effective. Cigarette smoking dramatically increases the risk of lung cancer, but a significant number of people who have never smoked do get the disease.

Plus, about one-fourth of people with early lung cancer don't have symptoms. For many, the disease is diagnosed when they get a chest X-ray for some other reason, but by then the disease may be well advanced.

Lung cancer deaths have declined along with smoking rates. But even so, the American Cancer Society says the disease will kill more than 157,000 Americans this year.

A blood test

The overall survival rate for the most common type of lung cancer is 15 percent, five years after diagnosis, according to the Centers for Disease Control and Prevention. If found early, when the tumor is about an inch in size and has not spread outside the lung, survival is 60 to 80 percent.

But most lung cancer is found after it has spread. So the announcement of EarlyCDT-Lung, a $475 blood test to detect lung cancer early, was exciting to many. It was launched last year through more than 400 physicians' offices in the Midwest and Southeast, but patients can buy it online from the manufacturer, Oncimmune, and ask their doctor to draw blood and send the whole thing back to the company's laboratory in De Soto, Kan. It hasn't received FDA approval, Oncimmune says, because as a laboratory-developed test, it doesn't need it. (An FDA spokesman said this week that the agency is still considering whether such tests should fall under its purview.)

Oncimmune says it can find lung cancer before it is evident on a CT scan. But not always.

Tested in hundreds of people already known to have lung cancer, EarlyCDT-Lung detected cancer in only 40 percent. But given the lack of alternatives, some physicians are still offering the test.

Inconclusive results

The doctor closest to the Tampa Bay area that the company could offer for an interview is Dr. Lee Collier (PDF), an internal medicine specialist in Dublin, Ga. He offers it to his high-risk patients — those who smoke or have smoked — for a simple reason. "Maybe it will save some lives," he said.

But in his two patients with positive test results, cancer hasn't been diagnosed. In one, an abnormal growth was found, but it was too small to biopsy, so the patient must be retested in six months or a year. The second patient whose blood test was positive had a negative CT scan. Collier said, "He's a heavy smoker, so we checked other possible things that could give us a positive result, such as prostate cancer, and they were all negative. So we'll follow him and screen him every six months."

Letting down your guard

Tampa's Moffitt Cancer Center, however, isn't recommending the Oncimmune test. "It's an interesting development and merits further study, but it isn't something I would call promising," says Dr. Mary Pinder-Schenck, a lung cancer specialist at Moffitt.

She thinks it has been made available to consumers prematurely, with potentially devastating consequences.

"It went really fast from 'It's in the lab' to 'We're marketing it to patients,' '' she said. "We prefer to see something really tested."

As controversial as mammography has been for breast cancer screening, that test picks up the disease 75 to 90 percent of the time, she noted.

What's the possible harm in a simple blood test for lung cancer? Pinder-Schenck worries that smokers and former smokers may have a negative test result and think they are safe from lung cancer, then ignore a chronic cough, shortness of breath or some other warning sign that develops a month or a year later.

"What (Oncimmune) haven't shown is, can they actually save lives?''

Testing the CT option

The large study on CT scans for early detection of lung cancer is ongoing. The National Cancer Institute website says some results from that study, which recruited more than 50,000 patients, may be available this year or next. In the meantime, experts don't recommend that smokers and other high-risk individuals demand a CT scan from their doctor or go for routine lung screening at one of the many full-body scan centers where no prescription is required and patients pay the full cost (generally $300 to $1,000). Only those enrolled in a clinical trial should have the spiral CT screening, according to Pinder-Schenck.

"It's a substantial amount of radiation," she says. "If we have a healthy person without cancer and we subject them to radiation, it's problematic." Plus, as with Oncimmune, the test is far from pinpoint accurate. According to the NCI, spiral CT scans of smokers and former smokers show abnormalities that are not cancer 25 to 60 percent of the time.

Irene Maher can be reached at imaher@sptimes.com.

Researchers hunt for reliable early-detection test for lung cancer 07/28/10 [Last modified: Monday, August 2, 2010 5:29pm]

© 2014 Tampa Bay Times

    

Join the discussion: Click to view comments, add yours

Loading...