The Truth About Lung Cancer Screening and Prevention
Lung cancer is the #1 cancer killer in the US, accounting for more death than the next 3 most common cancers combined (colorectal, breast and prostate cancers).
Since survival for lung cancer is very much related to being able to catch it early, early detection, meaning state I or II lung cancer, or before lung cancer becomes more advanced and spreads to distant lymph nodes and tissues, will result in improved survival in this devastating disease. However, only limited progress has been made in the area of early detection; previously, chest x-rays had been routinely used for early screening, resulting in methods with sub-optimal, low likelihood of early detection.
Recently, implementation of low-dose CT of the chest has been shown to significantly improve early lung cancer detection, and reducing mortality from lung cancer by as much as 40%.
However screening criteria to qualify for low-dose CT of the chest are quite stringent, and are a function of one's extent of smoking, age and functional status. In fact, these criteria are so stringent that two-thirds of patients who are ultimately diagnosed with lung cancer do not meet the stringency criteria to qualify for a screening CAT scan. Put another way, because screening guidelines demand such stringent criteria in order to qualify patients for screening CAT scans, only about 30% of patients who are ultimately diagnosed with lung cancer can actually get these types of screenings.
While we do know that about 85% of lung cancers are smoking related, a relationship with smoking is certainly complex and multi-factorial, such that additional other risk factors including genetic, environmental, occupational, and even dietary do play significant roles.
Hence if a person does not necessarily meet the stringent smoking criteria, to qualify for a screening CAT scan of the chest, this individual may still have a significant risk of contracting cancer because of the combination of other inhalation, environmental or family related risk factors. All of these risk-factor contributors would need to be taken into account to come up with each person’s individualized lung cancer risk, and, by so doing, will hopefully expand the screening pool such that majority of patients who are at risk will in fact get appropriate screening.
With regards to the more exciting, cutting-edge screening technology, additional screening with blood testing in trying to detect early circulating tumor DNA components have been shown to augment our ability to detect early lung cancer with 80+% accuracy. This type of testing is part of what’s called a liquid biopsy, which aims to look at a patient’s serum to detect any concerning tumor DNA signature.
There’s a lot of excitement about incorporating a tumor DNA liquid biopsy’s signature to augment our ability to detect aggressive cancers early, with lung cancer being in the forefront of this effort.