Positron emission tomography (PET) can save hospitals tens of thousands of dollars in the evaluation of patients with suspected lung cancer and provide more accurate disease staging than conventional imaging tests, according to a report presented at the recent meeting of the Society of Nuclear Medicine. A multicenter clinical trial shows that PET scanning can provide crucial information that helps determine whether solitary pulmonary nodules need to be surgically removed. By scanning the lung with fluorine-18 [18F]-fluorodeoxyglucose (FDG), a radiotracer analog of sugar that visualizes metabolic function, imaging specialists can identify which lesions are malignant and which are benign.
To measure the accuracy of PET in these circumstances, 89 patients whose chest x-rays and CT scans showed lung nodules underwent PET-FDG scanning. Results showed that PET lung scanning with 18F-FDG has an accuracy of 85% to 90% in differentiating malignant from benign nodules. Malignant tumors show more radiotracer uptake of 18F-FDG than benign tumors.
"A negative PET-FDG study can justify a decision not to surgically remove the nodule in the lung," said
R. Edward Coleman, MD, director of radiology and nuclear medicine at Duke University. "With the increased accuracy provided by PET scanning, about 10,000 patients per year in this country can avoid unnecessary lung surgery." Thoracotomy, according to the investigators, costs approximately $30,000.
Thus, say the researchers, this clinical trial should convince more third-party payors and managed care organizations to cover the costs of PET scanning. In the long run, the health-care system would save a great deal of money if PET results were used to help determine which patients should undergo surgery.
Another Study, From UCLA
Cost savings with PET lung studies are also reported by physicians at the University of California in Los Angeles School of Medicine. When hospitals add a whole-body PET-FDG scan to the diagnostic workup of patients with non-small-cell lung cancer, they can save an average of $204 per patient without reducing overall life expectancy. The cost savings come primarily from avoiding surgery in patients whose disease is too far advanced to be successfully removed. PET can show metastatic spread of lung carcinoma that is missed by CT and other diagnostic imaging tests, according to the UCLA group.
"When you multiply that $204 by the estimated 120,000 people diagnosed in the US each year with non-small-cell lung cancer, you can see that PET scanning could save about $24.5 million in nationwide healthcare costs,"said Sanjiv S. Gambhir, MD, PhD, assistant professor, of molecular and medical pharmacology at UCLA. In fact, Dr. Gambhir said, further analysis of their data showed that their assumptions of the accuracy of CT in these patients were overestimated. "Our revised data indicate that hospitals can actually save $1,114 per patient when they include whole-body PET in the diagnostic workup of patients with non-small-cell lung cancer. By using PET, the annual cost reduction to the US health-care system could total $133.7 million," Dr. Gambhir said.
"This estimated savings is based on a clinical decision tree that shows the probability of a patient having lung cancer based on results of various diagnostic tests," said Dr. Gambhir. The decision-tree analysis assumes the following costs for diagnostic tests:
- CT, $700;
- PET, $1,200;
- Mediastinoscopy, $3,000; and
- Thoracotomy, $30,000.
In a study of 20 patients with non-small-cell lung cancer, whole-body PET scanning with 18F-FDG provided additional information that changed the stage of disease in 7, or 35%, of patients. Disease staging was originally based on conventional imaging methods, such as CT, MRI, and radionuclide bone scanning. In general, physiologic imaging with PET detects malignancies that are missed by anatomic imaging methods, such as CT and MRI.
"Cancer is a multiorgan disease," noted I. Madar, PhD, of UCLA. "Whole-body PET imaging can detect malignancies throughout the whole body--in both soft tissues and bone--with one scan that takes about an hour. In current practice, patients with cancer typically undergo three CT scans (chest, abdomen, and pelvis), an MRI brain scan, and a radionuclide bone scan to get the same whole-body information. Besides the extra time and cost of so many scans, parts of the body can be missed because often there are anatomic gaps between the chest, abdominal, and pelvic CT scans."
The total cost of disease staging by PET for all 20 patients was $25,000, far less than the $42,406 total for conventional imaging methods. "Including PET as a supplement to CT provides information that helps oncologists plan the most effective strategies for surgery, radiation therapy, and/or chemotherapy for individual patients," said Dr. Madar.
In general, lung cancer that has spread to the media- stinum is considered inoperable. CT has a tendency to show lesions in the mediastinum that are false-positive. Traditionally, physicians need to do exploratory surgery to see if the lung cancer has really spread this far. "However, if the patient has a PET scan that shows malignancy in the mediastinum, thoracotomy can be avoided," said Dr. Madar. "If the PET scan shows no radiotracer uptake in the mediastinum, there is more hope that the lung cancer can be surgicaaly removed."
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