Early Imaging with PET Does Not Reduce Number of Diagnostic Tests for cancer

Early Imaging with PET Does Not Reduce Number of Diagnostic Tests for Non-Small Cell Lung Cancer

A randomized clinical trial from The Netherlands has reported that use of positron-emission tomography (PET) as soon as lung cancer is suspected does not reduce the overall number of diagnostic tests performed for non-small cell lung cancer. These results were published in the Journal of Clinical Oncology.

Lung cancer remains the leading cause of cancer death in the U.S. Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for 75%-80% of all lung cancers. When a diagnosis of lung cancer is confirmed, determining the stage or extent of spread of the cancer is essential to making treatment decisions.

Imaging techniques such as PET and computed tomography (CT) can be used to stage NSCLC before surgery. A CT scan uses computer-controlled x-rays to create a three-dimensional image and show the extent of the disease. A CT scan is more sensitive and precise than a standard chest x-ray.

PET scans are often used to improve the detection of cancer in lymph nodes. Prior to a PET scan, a substance containing a type of sugar attached to a radioactive isotope (a molecule that spontaneously emits radiation) is injected into the patient’s vein. The cancer cells “take up” the sugar and attached isotope. The low energy radiation emitted by these cells helps physicians locate cancer.

A more recent option for imaging is the integrated (combined) PET-CT system. This system was developed to overcome the limitations of CT or PET used alone.

In order to evaluate whether early use of PET (use as soon as lung cancer is suspected) reduces the overall number of diagnostic tests required to accurately stage NSCLC, researchers in The Netherlands conducted a randomized clinical trial among 465 patients.

Patients were randomly assigned to receive either usual care (which did not include immediate PET) or imaging with PET as soon as lung cancer was suspected. Suspicion of lung cancer was based on history, physical examination, and chest x-ray.

  • The number of diagnostic tests required to finalize staging was similar in the two groups.
  • The frequency of invasive tests was lower among patients in the early PET group than in the usual care group.
  • Both approaches (traditional vs. early PET) provided accurate information about lung cancer stage.

The researchers conclude that early use of PET does not simplify the staging of NSCLC, although it does provide accurate information with the use of less invasive surgery. Because of the promising results of other studies with the integrated PET-CT system, the researchers suggest further evaluation of that approach.

An accompanying editorial agrees that integrated PET-CT systems appear to provide the most precise available staging information, and that once these systems become more widely available they will likely become the preferred approach for determining NSCLC stage in selected patients.

Reference: Herder GJM, Kramer H, Hoekstra OS et al. Traditional Versus Up-Front [18F] Fluorodeoxyglucose-Positron Emission Tomography Staging of Non-Small-Cell Lung Cancer: A Dutch Cooperative Randomized Study. Journal of Clinical Oncology. 2006;24:1800-1806.

Accompanying Editorial: Lardinois D. New Horizons in Staging for Non-Small-Cell Lung Cancer. Journal of Clinical Oncology. 2006;24:1785-1786.

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