Lung Cancer Screening: Excellent for Lung Cancer Detection, Still Questionable for Incidental Malignancies

The recently released National Lung Screening Trial has shown very promising results in CT screening for lung cancer.  Screening trials may be hampered by various biases; however the NLST answered the bottom line.  Is mortality in screened patients better than in those that aren’t screened?  The NLST showed a 20% reduction in lung cancer related deaths in screened patients.

In the wake of these findings, UCSF Radiology and Biomedical Imaging and UCSF Pulmonary have paired up to establish the UCSF Lung Cancer Screening Program.  The program, which is currently running, includes a low- dose CT scan and a consultation with a UCSF pulmonologist. Appropriate candidates for the LCSP are patients between the age of 55 and 74 years old who currently smoke, or have quit smoking within the last 15 years. In order to make this potentially life saving program available to as many patients as possible, the LCSP is being offered at a discounted price.

In addition to these promising results from the NLST, there will be many ancillary studies to emerge from the NLST and other lung cancer screening trials. Many of these should be interpreted with a greater level of skepticism, as they may not be as reputable as the initial findings that prove the benefit of lung cancer screening. One of these studies, entitled “Extrapulmonary malignancies detected at lung cancer screening,” appeared in a recent issue of Radiology.  This study examined the number of cancers outside of the lungs that were incidentally discovered as part of low dose CT lung cancer imaging from the COSMOS trial.  The authors discovered 27 unsuspected cancers outside of the lungs out of a total of 5201 patients who were screened.  The tumors included cancers of the kidneys, lymphatic systemic, thymus, pancreas and liver amongst others.

Upon initial review, this information seems like an unexpected benefit of CT lung cancer screening.  It is able to find unsuspected cancers and these patients can undergo treatment for these tumors.  However, this data should be viewed with a critical eye.  A total of 436 “potentially significant incidental findings” were found.  Each of these required some additional evaluation including more imaging, biopsies, surgeries, etc.  From this group of 436 patients with potentially significant incidental findings, only 27 cancers were diagnosed.  This means that 94% of the patients with potentially significant incidental findings did not have a cancer.  All of these patients were subjected to additional studies that could have complications of their own, not to mention the emotional stress of having a possible life-threatening diagnosis.

In summary, the discovery of incidental cancers using low dose CT screening is encouraging; however this finding must be interpreted with a healthy dose of skepticism.  While lung cancer screening is proven to be very promising in lowering the mortality rate of patients with lung cancer, the benefits of discovering unsuspected cancers outside the lungs should be viewed critically.

The Lung Cancer Screening Program is being offered to patients for a discounted self-pay price. For more information, please click here.  To schedule an appointment, please call (415) 514-8787.