The published study is available by clicking the above link
My concern and or contention with using imaging to screen for lung cancer in high risk groups (i.e. smokers) is complex. First, whether it be a chest x ray with minimal radiation exposure, low dose CT or a max dose diagnostic spiral CT - the screen itself can be carcinogenic, and second, it takes the focus off other smoking related lung diseases which impact a greater number and at lower dose of smoking. Both COPD and Lung Cancer are irreversible, fatal conditions. Lastly, more smokers die of heart disease than either of the above - when the death certificate is completed, anyways.
In an article regarding the recent results of the National Lung Cancer Screening Trial - a medical doctor (i.e. I am NOT a doctor) notes that lung cancer seems to be the cancer that gets the least respect. He noted that mammograms are never questioned (except that these days they are), and maybe he has a point about lung cancer not being given respect. When I read the article and the study results - which I will get to in a moment, I thought of my dearest Aunt Jay who did die of lung cancer after years of hardcore smoking. If she had been the recipient of these screenings would that have saved her life, extended her life, extended it in a productive way that was free of pain? Would it have made a difference? Surely, if it would have, then I must rethink my stance. I do not know the answer and I don’t think the scientists do either. Lung cancer, specifically the small cell lung cancer that is most related to cigarette smoking - is nearly always fatal and fatal quickly. That “quickly” is within years of diagnosis. If we now diagnose it late and a person dies within five years, does earlier detection mean anything more than one will die within ten years instead of five? Or perhaps, with an earlier diagnosis one could quit smoking and ease the suffering or intensity of what would surely come in any case? I do not know. I know this however - more persons who smoke have emphysema and chronic bronchitis and spirometry is a cheap and non invasive procedure that can detect it in order to treat it. No one seems outraged about its lack of use in high risk groups. Indeed, COPD seems to be the lung illness that gets no respect. Is it a financial thing? Certainly the spirometry industry isn’t going to make a lot of money if we make sure all smokers get THAT test.
As a public health educator/health promoter (and not a health care professional) I do not at this time have any positive thought on CT screening for lung cancer in smokers as a preventative measure. The only preventative measure that I endorse for lung cancer is quitting smoking or never starting.
From the now published results of the NLST I offer a few points that I consider important. Usually when reviewing a research article the first things review are what they did and what they found
That gives you a heads-up on the subject matter - to see if it is of interest to you. But to see if the findings are of any real value it is better to look at HOW they did what they did and WHO they did it with.
This study has some good qualities in that in took a large group of volunteers who met certain criteria and with their consent, randomly assigned them to two groups. The follow up that occurred for the next six to seven years included a once a year screen (CT or X ray) for three years. The people were followed to see who among them was diagnosed with lung cancer (who lived, who died) in that seven years and if the CT found more of those cancers sooner than the Xray. It did, but it also found a whole lot of lung cancers that were NOT lung cancers. Those false positives would have to be ruled out with additional diagnostic examinations, including more imaging. In the CT group there were more positive findings for each of the three years in which screens were conducted. However, the rate of false positives was high for BOTH the Xray and the CT - 94 to 96 % respectively.
As mentioned above, it is important to know who the study involved. In this case, there were over 53,000 persons. The persons enrolled had to be considered heavy smokers or smokers who had been heavy smokers and quit in the last 15 years or less. That is important. They chose the people that they thought were most at risk for getting lung cancer during the study period of less than ten years. To be considered a heavy smoker the person had to have a 30 pack-years history. That means that they had to smoke one pack a day for 30 years or two packs a day for 15, etc. A plurality of participants were between 55 and 59 years of age (42%) and another between 60 and 64 (30%). Six of the people were under age 55 and 4 were over age 75. A majority of the participants were male (60%), white (90%) and 48% were current smokers.
Looking over the study again - I read this sentence …“Small-cell lung cancers were, in general, not detected at early stages by either low-dose CT or radiography.” Well - that is something that is not talked about so much in the news reports of the study.
The published article also has a figure with two graphs comparing the screenings. In the top graph are the number of lung cancer cases found (y axis). There is a line for the CT and a line for the X ray. In the bottom graph is the number of lung cancer deaths and again, a line for CT and a line for X ray. The horizontal axis is the years since the participants were in the study 0 to 8. In the lung cancer cases the CT line is on top (finding more) and in the lung cancer deaths, the Xray line is on top. In other words, during the study period of less than 8 years, there were more deaths in the x ray screened lung cancer cases than the CT screened cases. This only convinces me that the CT group is living longer with a diagnosis - not that they are living longer than they would have without the CT scan.
