Physicians have lamented for decades the absence of a reliable screening test for lung cancer, and they’re going to have to hum that tune awhile longer since the latest study of chest CT confirms previous findings: the test has an unacceptably high false positive rate.

The disappointing findings were reported by the NIH’s Jennifer Croswell at the recently completed meeting of the American Society of Clinical Oncology.

“False-positive results may create increased psychological stress in patients and an increased burden on the healthcare system,” Croswell told MedPageToday.

In Croswell’s blandly named Lung Screening Study, 1,610 participants received a baseline CT and 1,580 got a chest X-ray. Both groups received a repeat imaging study a year hence and were followed for another year.

The scientists defined a positive test as one revealing a noncalcified nodule at least four millimeters in diameter, or any other finding that was suspicious for cancer.

They defined false positives as positive screens that prompted a negative work-up or that resulted in no cancer diagnosis 12 months later.

The false positive rate for participants receiving CT scans was 21% after the first image and 33% after the second.  It was 9% and 15% for those receiving chest x-rays.

In the CT group, false positives tests prompted invasive diagnostic procedures and major surgeries in 6.6% and 1.6% of the participants, respectively. Those numbers were 4.2% and 1.9% for false positives resulting from a chest X-ray.

According to Peter Bach of the Memorial Sloan-Kettering Cancer Center in New York, “nothing really changes here,” as a result of the new study. “There is no organization in the world that recommends screening for lung cancer with CT,” or any other technique, Bach told MedPageToday.

The glycated hemoglobin, or HbA1c blood test has been approved as a legit means to diagnose diabetes.

An international committee of experts made the announcement at the recently concluded meeting of the American Diabetes Association.

The test is fit for use, it concluded, in people of all ages but not for pregnant women.

“This is a major departure from the way diabetes has been diagnosed in the past,” David Nathan told USAToday.

Nathan, the director of the Diabetes Center at Massachusetts General Hospital, chaired the august body which included investigators from the ADA, the International Diabetes Federation (IDF), and the European Association for the Study of Diabetes (EASD).

The committee based its conclusion on a review of scientific literature on the matter.

Prior to the announcement, diabetes had been diagnosed using either a fasting blood glucose or an oral glucose tolerance test. Both tests are sensitive but prone to false positive results caused by eating prior to the test and intercurrent illnesses.

In contrast, the HbA1c test assesses glucose levels over the 2-3 months prior to the stick. It is not nearly as likely to produce a false positive result, does not require that one fast prior to the test, and can be done at any time of the day.

The thing that had been preventing the test from being used as a diagnostic tool before the announcement was that influential diabetes groups had not agreed on the result that constitutes a positive diagnosis.

Nathan’s group more or less settled the matter, saying that anyone with a level of 6.5% or higher had diabetes.

The ADA itself has yet to sign off of these recommendations, however. It’ll begin its own investigation in the near future.