Giving Smokers a False Sense of Security: New Lung Cancer Screening Guidelines

   In December the United States Preventative Task Force completed its review of the available science on whether using a  low dose CT scan could reduce the number of lung cancer deaths.  Lung cancer is the most lethal cancer, likely due to its late detection.  Treatment in late stage lung cancer is seldom successful, and is invasive (i.e., surgery, radiation, chemotherapy).
    The task force members reviewed 6 effectiveness studies and 20 studies that explored adverse effects from low dose CT - including exposure to radiation, the rate of false positives and the associated stress and unnecessary procedures that follow false positives.  You can read the summary and full report from the task force here. 
   It appears that only one of the studies that found a protective effect from low dose CT  was of high quality.  That study showed reduced lung cancer death as well as reduced death from any cause (all cause mortality) in the smokers who received the CT. The evidence from this study and several moderate quality studies was convincing enough to some to recommend the screening change.
    I am addressing the issue in my blog for two reasons, 1) I have worked in the smoking cessation field and 2) I often post about medical radiation and my grave concern over excessive use of imaging.  Almost four years ago, I wrote this post which was an over view of chapter 4 in the President's Cancer Panel report on Reducing Environmental Cancer Risk.  Chapter 4 is Exposure to Hazards from Medical Sources.  From that chapter we learned that CT scans are over used, that they expose the patient to high levels of radiation (higher levels than are necessary for the scans to be effective) and that the radiation dose from a CT scan can increase a person's risk for cancer.
   The new recommendations are for physicians to offer the low dose CT (LDCT) to persons who are between the ages of 55 and 74 who have smoked 1 pack of cigarettes per day for 30 years or 2 packs per day for 15 years, or any other combination that would equal 30 pack years.  If a person has this smoking history, but has quit smoking, they should still have the screens if they have been smoke free for less than 15 years.  [Notice the significant screening criteria - SMOKERS only.  To me this is as strong a declaration on the lethal consequences of smoking as one will ever hear.]
   According to the task force, 20% more lung cancer deaths could be prevented if these heavy smokers were screened with LDCT instead of a chest x-ray.  I do not know what this means in actual numbers, i.e., 20% of how many - how many do X rays find?  
   What I did spend time looking for was the amount of radiation a low dose CT provided.  Recall from chapter 4, not all imaging machines deliver the same amount per test .. so a rough estimate is the best we can do. The estimate is that low dose CT delivers the radiation equivalent of about 15 xrays.  Fifteen!  Radiation in this case is measured as millisieverts, or mSv.  A regular chest CT has 5 to 20 mSv and the low dose CT has 1 to 4 mSv.  Better - still a heck of a lot and more than I would routinely expose myself to.  (To be fair, some estimates of  the radiation in regular chest CT suggest the equivalence of 350 Xrays... yes that is three hundred - so to answer my question; indeed, the low dose CT is a lower dose of radiation)
   In the summary from the report, it is clearly stated that most lung cancer is caused by smoking and that the most important thing we can do to reduce death and disease from lung cancer is to reduce smoking.
    I am really concerned that smokers will keep smoking because they believe that this screening will find a tumor in time to remove it.  That is a HUGE risk.  Click here to learn more about quitting.. I did it, so can you.

Living Longer - but still terminal

NLST 

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.

Tumor Analysis

This morning I read a brief news statement about a lung cancer clinical trial referred to as BATTLE that is underway at the M.D. Anderson Cancer Center in Texas. I have since contacted the reporter, reviewed the study website, read the study particulars on the US Institute of Health website for clinical trials, skimmed over several scholarly articles and then, read an article by another reporter which HAD the piece of information I needed in order to proceed with this post.

The study is a promising one which is addressing the treatment of the deadliest cancer - cancer of the lung. In the Anderson study, persons who have late or end stage non small cell lung cancer (nsclc) and who meet certain inclusion criteria - including having been through one course of first line treatment - (FDA approved medication for lung cancer treatment) - which did not slow or stop the progression of their cancer are entered into part one of the study, or the umbrella phase.

All of the persons have tumors ( small cell lung cancer, the most common one for smokers, tends to be diffuse) and these tumors are biopsied. Each tumor has characteristics and based on those characteristics, the volunteers are placed into one of four groups for part two of the study. This is a Phase II drug trial. They are put on a study medication for 8 weeks and then the tumor characteristics are reviewed again. A successful outcome is when the disease does not progress and people do not die. If progression has occurred, the person is taken out of the study and allowed to go on to receive standard treatment through their own provider.

I understand that tumors can have different fuels and expression - we often hear a distinction between estrogen receptor positive or negative breast cancer. That is what I was trying to find out with regard to this study.

So yes, lung cancer tumors can be fueled by different proteins, can be a result of expressions of certain genes, or be caused by a mutation on a certain gene. It is this distinction that the scientists make before putting the patient on one of the study drugs. Some success has been noted already with certain medications and tumor types. The study is not complete and full disclosure is pending.

I wonder if the tumor histories are used to tell what type of nsclc a person has. I also wonder if tobacco use is allowed during the study and if the patients were tobacco users. I did not see tobacco use as an exclusion for the study, but I did see this statement: Any condition that is unstable or could jeopardize the safety of the patient and its compliance in the study, in the investigator's judgment. I would consider smoking during treatment of lung cancer something that could jeopardize safety - wouldn't you?

This is a promising study - but to be clear, most persons with advanced stages of lung cancer do not live past a year. In the second article I read, it was noted that of the people in the study receiving this personalized approach to care, 38% survived to one year. I read that as 58% died. And nsclc is supposed to have a better survival rate that small cell lung cancer.

I would like to know if the type of nsclc was determined, as there are three - adenocarcinoma, squamous cell carcinoma and large cell carcinoma. Do the proteins, mutations,or expressions determine that categorization or are their various biomarkers within disease type as well? Perhaps this will be answered when the study is published - if not - I will seek answers from a cancer organization.

Over 80% of lung cancer is caused by tobacco smoke - the most common nonsmoker lung cancer is the nsclc described here - however, even that type is most often caused by smoking.