Medical News: ASCO: False Positives Common in Lung Cancer CT Screening – in Meeting Coverage, ASCO from MedPage Today

A positive screen was defined as any noncalcified nodule at least four millimeters in size or other radiographic finding deemed suspicious for cancer.

A false positive was defined as a positive screen with either a completed negative work-up or at least 12 months follow-up with no cancer diagnosis, the researchers said.

Analysis showed:

* An individual’s cumulative probability of at least one false-positive CT scan was 21% after one screen and 33% after two.
* For chest X-rays, the cumulative probabilities were 9% and 15% after one and two screens, respectively.
* In a multivariate analysis, people over 64 years of age had a 34% increased risk of a false-positive CT scan.
* Of those getting a CT false positive, 6.6% had an invasive diagnostic procedure and 1.6% had major surgery, compared with 4.2% and 1.9%, respectively, for chest X-ray false positives.

There are no screening methods for lung cancer that have been shown to reduce death and illness from the disease, which is often only detected in its late stages.

According to the American Cancer Society, the five-year survival rate for localized lung cancer is 49.5%, but that falls to 20.6% for disease that has spread outside the lung and 2.8% if there are distant metastases.