Good Old X-Rays For Spotting Lung Cancer

Chest Xrays for lung cancer screening may not be an ineffective tool for high risk individuals

(RxWiki News) Chest X-rays are cheaper than CT scans, but are not routinely used to screen people who are at risk for lung cancer.

In a recently published review, the authors examined results from other studies to show that screening with chest X-rays may be an effective method to detect lung cancer early.

Previous studies had suggested that CT screening reduces lung cancer mortality when compared to chest X-ray screening, which was considered ineffective. 

The authors of this study concluded that evidence from previous studies indicates that chest x-ray screening is still better than no screening, and the amount overdiagnosis in the context of chest x-ray screening is small.

"Ask your doctor about early detection of lung cancer."

This review was conducted by Gary M. Strauss, MD, MPH, from the Department of Medicine at Tufts University School of Medicine in Boston, Massachusetts, and Lorenzo Dominioni, MD, from the Center for Thoracic Surgery at the University of Insubria in Varese, Italy.

The primary aim of the review was to analyze and evaluate existing studies that looked at chest X-ray as a screening tool for lung cancer.

Chest X-rays have not been considered an effective method for lung cancer screening. In a large clinical study known as the NLST trial, screening for lung cancer with X-rays was shown to have a lower effect on reducing the number of deaths in the population as compared to screening using CT scans.

Also, previous studies have suggested that screening with X-rays leads to overdiagnosis of lung cancer and subjects the patients to unnecessary tests and more radiation that may in turn increase cancer risk.

Overdiagnosis means that the patient is incorrectly diagnosed as having lung cancer or that the cancer is so slow-growing that it will not affect the patient during his or her lifetime. Overdiagnosis also occurs when other conditions may kill the patient or cause symptoms before the lung cancer can. 

According to an editorial related to this review, this aspect of screening using X-rays has been responsible for delays in implementing screening programs for lung cancer.

For the review, the researchers looked at many previously conducted studies that examined the effectiveness of lung cancer screening using X-rays.

All the studies the researchers analyzed were initiated in the 1970s. The studies included a total of 37,724 male smokers.

The review highlighted certain results from previous studies.

For example, in a study conducted by Memorial-Sloan Kettering, five-year survival for lung cancer was 35 percent as compared to 10 percent for the general population.

In another study called the PREDICA trial, screening using chest X-rays was shown to be associated with an 18 percent reduction in lung cancer-related deaths as compared to no screening.

An example highlighted to examine the possibility of overdiagnosis was a Czech study. During its initial phase, the study demonstrated a 50 percent greater number of deaths from lung cancer in patients screened using X-rays, as compared to patients who were not screened.

But during the second phase of the study, it was shown that the difference in the number of lung cancer deaths could have been due to inherent differences in lung cancer risk between the screened group and the group that was not screened.

The researchers suggested that there were similar discrepancies in the results of the Mayo Lung Project, which showed that chest X-rays led to overdiagnosis and were not associated with lower lung cancer death rates.

Overall, the authors of this review argued that previous studies demonstrating ineffectiveness of lung cancer screening using X-rays could be interpreted differently. Also, overdiagnosis occurred mainly in certain types of lung cancer and could be avoided by taking certain clinical measures.

“We do not agree with the widespread and long-held belief that chest X-ray screening is ineffective,” the review authors wrote.

“While NLST shows that CT screening is superior to chest X-ray screening, chest X-ray is a widely accessible and relatively inexpensive screening tool that can still have a substantial role in reducing lung cancer mortality,” they wrote.

It must be noted that no independent research was conducted for this review, which examined many different previous studies. Also, data can be interpreted differently by different researchers, so the results of the review may be open to interpretation as well.

According to Professor of Medicine and Pathology at the University of Colorado Cancer Center, Dr. Fred Hirsch, "The authors conclude that conventional chest X-ray also reduce lung cancer mortality and is better than 'no screening' for lung cancer. The results and conclusions are interesting and the authors have a valid point, but probably not so relevant today with more modern technology."

"The NLST results showed clearly significant reduction in lung cancer deaths with low-dose CT when comparing low-dose CT with conventional chest X-ray so I don't believe an analysis of the old screening studies performed decades ago will change the future perspective of screening high-risk individuals with low-dose CT scan."

"I believe that low-dose CT will be the platform to build upon- and not conventional chest X-ray- when implementation of lung cancer screening occurs," said Dr. Hirsch, who was not associated with the study.

This review was published August in the Journal of Surgical Oncology.

No conflicts of interest were disclosed by the authors. Funding information was not provided.

Review Date: 
August 31, 2013