SUNDAY, Sept. 9, 2001 (HealthDayNews) -- A new kind of "imaging agent" can improve the detection of lung cancer that has spread beyond the lungs, leading to better care and fewer unnecessary or inappropriate surgeries, contends new research.
The imaging agent, Tc-99m Depreotide, was 30 percent more effective than a CT scan alone in detecting cancer that had spread from the lungs to the lymph nodes in the central area of the chest, called the pulmonary hilum and mediastinum, the study says.
"We are finding it is more sensitive in detecting tumors than CT by far and even slightly more sensitive than the PET scan, which has been shown in the literature to be much more sensitive than CT," says lead author Dr. Alan Waxman, director of nuclear medicine and co-chairman of imaging at Cedars-Sinai Medical Center in Los Angeles.
Depreotide was approved by the U.S. Food and Drug Administration about a year ago.
In Waxman's study, 45 people with lung cancer were injected with Depreotide, and a nuclear medicine camera was used to take images of their chest and lungs. The scans were compared with biopsy samples collected four weeks earlier.
Depreotide's sensitivity to detect cancer and its ability -- or "specificity" -- to rule out cancer were measured by looking for lung cancer that had spread to the lymph nodes in the central chest, and by the agent's ability to find single pulmonary nodules, which are abnormal collections of cells in the lungs that may or may not be cancerous.
The study found Depreotide's sensitivity to detect these nodules was 94 percent, while its specificity to rule out cancer was 78 percent. For the lymph nodes in the central chest, Depreotide's sensitivity was 100 percent and its specificity 80 percent.
By contrast, CT scans were 60 percent sensitive for detecting cancer in the central chest nodes and 70 percent specific in ruling out cancer.
Depreotide's ability to provide a better picture of what's happening in the lungs and chest will help doctors make better decisions about patient care, the researchers say.
CT scans often fail to detect smaller tumors that may have spread beyond the lungs, experts say, and the scans may not be able to distinguish between cancerous and benign tumors. That means relying on CT scans alone could lead to unnecessary or inappropriate surgery, say the researchers. Findings were presented at a recent meeting of the Society of Nuclear Medicine.
Waxman says six study participants who underwent Depreotide treatments had strong positive results for cancer in the central chest nodes, but they did not show signs of cancer during initial analyses of biopsy samples. After the positive Depreotide results, he says, the pathologist re-examined the biopsy samples and found that two of the six people did indeed have cancer in their central chest lymph nodes.
"So it seems like this is a very sensitive agent in detecting some part of the cancer that has reached the lymph nodes," Waxman says. "This may be an agent that can predict where the cancer is going before it gets there."
He and his team are doing new research to determine if seemingly "false-positive" Depreotide results are a predictor of cancer that wasn't seen during initial biopsy tests.
What To Do
The American Cancer Society says lung cancer kills almost 160,000 Americans each year and is the leading cause of death from cancer for both men and women in the United States. It kills more people than colon, breast and prostate cancers combined. More than 169,500 new cases of lung cancer are expected to be diagnosed this year. Experts maintain that early detection and accurate diagnosis are critical to managing a patient's treatment and improving long-term survival rates.
For more information about lung cancer, visit the National Cancer Institute or the American Lung Association online.
