CT Screening Finds Lung Cancers Early
85% of Cancers Found in Study Were More Survivable Stage 1 Type
Cautious Optimism continued...
According to the National Cancer Institute (NCI), studies indicate that between a quarter to more than half of CT scans among smokers and former smokers show abnormalities, and in most cases these do not turn out to be lung cancer.
The problem is that malignant tumors and benign lesions often look the same on a CT scan, and decisions about how to proceed once a lesion is found are not clear-cut.
Potentially risky invasive procedures such as needle biopsy or even surgery are usually needed to confirm a diagnosis of lung cancer.
In the I-ELCAP study, patients with small but suspicious lesions were either tested again using a different screening method or had a repeat CT scan three months later.
When a lung infection was suspected of causing a lesion, a two-week course of antibiotics was prescribed and a repeat CT was performed a month later.
If the second image showed that the lesion or lesions had grown, a needle biopsy was usually performed.
Another concern about CT scanning is that it could result in the diagnosis and treatment of tumors that would never become life-threatening.
Overdiagnosis is impossible to document in living patients, but autopsy studies have shown undetected lung cancers in many people who died of other causes.
The I-ELCAP results appear to address this concern. Eight of the study participants whose stage I cancers were first identified through CT scanning were not treated, and all eight died within five years of diagnosis.
The NCI is conducting its own study to compare CT scanning to traditional chest X-ray for the early detection of lung cancerlung cancer.
The aim of the study, which includes 52,000 current smokers or former smokers, is to determine if regular screening with either test reduces deaths from the disease.
Results from the trial are expected by 2009, but Gary Kelloff, MD, of the NCI, tells WebMD they could come sooner if clear trends are seen before then.
"We still don't know if we are reducing lung cancercancer mortality in a screened population," he says. "The I-ELCAP trial was well done and it certainly adds to what we know. But we still have a lot to learn."
Kelloff is special advisor to the NCI's Cancer Imaging Program, in the Division of Cancer Treatment and Diagnosis.