Every year lung cancer extracts a terrible toll in this country.
Here are some of the numbers:
- Lung cancer is the leading cause of cancer death in the United States in 2006
- In 2006, 174,470 people will be diagnosed with lung cancer, and 167,050 will die from this disease
- 15 years of life are lost by the average person who dies from lung cancer
- 2,3643,900 years of life were lost in this country in 2002 from lung cancer
It is obvious that anything we can do to decrease the rate of deaths from lung cancer will have a huge impact on the health and length of life of this country.
As hard as many have tried, we still have around 20% of the adult population who smoke, and there is a continuing tobacco addiction crisis among young people in the United States.
For those who are smokers, and those who are former smokers who have quit using tobacco (who are now in the majority relative to those who have ever used tobacco), there has been little we can offer to prevent this disease.
And, up until recently, there has been no screening test that we can recommend to everyone who has been a smoker or exposed extensively to second hand smoke that might find lung cancer early and offer the benefit of saving their lives.
An article reported in today’s New England Journal of Medicine may go a long way to changing our perceptions regarding the benefits of screening for lung cancer in an effort to catch the disease early.
First, a bit of background.
About 30 years ago a series of studies were reported that indicated the best available screening with chest x-rays and sputum cytology (examining sputum samples of smokers for evidence of cancer, somewhat like a pap smear for the lungs) provided no survival benefit for smokers.
I can recall the papers—although interestingly they are not cited in the current report or an accompanying editorial—and the lectures from those years. The study researchers went out of their way to point out that even finding early lung cancers didn’t mean that the patients survived longer.
This finding was different from what we have seen in other cancers, namely that discovering a lung cancer earlier meant meaningfully longer survival for most patients, such as is the case for breast and colorectal cancer.
The result of those studies was that many organizations—including the American Cancer Society—came out against any form of routine screening for lung cancer, which at that time was predominantly done by chest x-ray.
As time has moved on, so has technology.
CT scans were not widely available until the mid-1970’s, and those CT scanners--although revolutionary at the time--were nowhere near as quick or technologically advanced as what we have available today.
There have also been some researchers in the medical community who have argued that the data interpretations from the original studies were flawed, and that there was in fact a benefit seen from screening in the earlier studies.
In the midst of this controversy, a group of researchers led by doctors from Cornell University in New York began a study of smokers and former smokers using more advanced CT scan technology which was able to clearly see small lesions in the lungs.
For several years they have been presenting their data, showing that they have been able to find lung cancers early, and that survival was considerably improved.
Along the way they have refined their study protocol to improve the accuracy of their procedures, trying to winnow down the many lesions they were finding in the lungs so that they would selectively biopsy only those with a high likelihood of being cancerous.
More recently, the American Cancer Society and others supported a trial called the National Lung Screening Trial which randomly assigned participants to either chest x-ray or CT screening. 50,000 people are participating in this trial, and the results of that effort are still several years away from being analyzed and reported.
In the current report from the New York group (which in fact is now an international effort) in today’s New England Journal of Medicine, the authors report the survival results from their study.
Those results are indeed very impressive, and strongly suggest that screening smokers, former smokers, people with occupational exposure (such as asbestos) and those who have had substantial second hand tobacco exposure is very effective in reducing deaths from lung cancer.
The researchers performed an initial CT scan lung screening for over 31,000 people without symptoms from 1993 through 2005. They also did another 27,456 follow-up CT screens on some of the same people between 7 and 18 months after the primary screen.
If they found an abnormality on the CT scan, the doctors followed a very specific protocol to determine whether or not the nodule did in fact have a high probability of being cancer.
This is important because doctors see many things in the lungs of smokers and former smokers that may look like cancer on the CT scan but are in fact not cancerous lesions.
That has been one of the downsides of doing this test, since there are risks associated with doing further workups on patients with suspected cancers. Those risks can include serious medical harm and even death, since many of these people are not exactly in prime health because of their smoking history and other medical conditions.
The important outcome of this study is that of the people that were screened with CT scan, either with an initial or a follow-up scan, 484 were diagnosed with lung cancer.
Of these 484 folks, 412 or 85% had stage I, or early stage, lung cancer.
For those 412 people with early stage disease, the estimated 10 year survival rate was 88%.
302 patients had their lung cancers removed within one month of diagnosis. For them, the estimated 10 year survival rate was 92%.
In other studies, the survival rate for Stage I lung cancer has been around 70%. When patients present with advanced Stage IV disease, the survival is 5%.
The most recent national data indicate that 16% of lung cancer patients present with localized disease, 37% with regional disease, and 39% with distant disease (7% are not staged).
Because so many folks present with more advanced disease, the overall five year survival rate from lung cancer in this country is 15.5% according to the latest available information.
You can begin to see why so many people are excited by the results of this screening study.
But there are some cautionary notes that have to be considered before we jump in with both feet and recommend every smoker and former smoker at high risk go out and get a lung scan to screen for lung cancer.
As pointed out in an editorial in the same issue of the New England Journal, we have not yet defined who really is at high risk of developing lung cancer, and would benefit from this screening. In fact, in this study, each participating group set its own criteria for entering someone into the trial. Entry requirements were not uniform among all the participating centers.
The study was not a “gold standard” type of study, namely a controlled clinical trial which would definitively answer the question of whether or not the benefits observed would apply to large numbers of people generally screened and treated in community settings (although it should be noted that community hospitals were included in the currently reported trial).
As with every other screening program, we are going to find cancers that would otherwise not cause harm to the person because of the different ways different cancers behave. This is particularly true of prostate cancer, but we haven’t had the technology or protocols available to us to even remotely consider such a situation with lung cancer. What this means is that we might be finding many small, slow growing lung cancers that in the past we would have never known about and would not have caused the patient any harm.
The editorial writer also points out that tumors located in the central part of the lung are more difficult to see by lung CT scans.
In this study, many of the cancers that were detected were adenocarcinomas, which tend to located in the periphery of the lung. In fact, 66% of the cancers were of this cell type.
In the past, when the previous screening trials were conducted, the majority of the lung cancers were of the squamous cell type which tend to be more centrally located. Also, the percentage of small cell lung cancers—typically the most virulent lung cancer—in the current study represented only 16 of the 412 cancers, or close to 4%. That is far less than was the case years ago.
One other comment in the actual study report that I noted was that “all participants were considered fit to undergo thoracic surgery.”
When you care for people who are at the highest risk for lung cancer, they generally tend to be older, have serious lung and heart disease among other medical conditions and are frequently not candidates for surgery. That may explain why the surgical death rates for people treated for their lung cancer in this study who died within one month of their surgery was 0.5%, compared to the usual 1.0%.
That same requirement may have also excluded a number of people from the screening study who are at high risk of developing lung cancer, and may explain why so many of the cancers were stage I, when one might expect a larger number of people initially screened for lung cancer to have more advanced disease.
None of these comments, however, diminish the importance of this study.
First, it’s important to remember that the goal of this particular report was to update the survival expectations of people screened in this study.
No one can ignore the fact that those survival statistics were outstanding, and far better than we could have anticipated.
Second, there are still other randomized trials underway which may shed more light on whether in fact mortality from lung cancer is reduced by screening in the community setting. It may seem like some of us are setting the bar too high by waiting for the results of these trials, when the data is so encouraging from the study reported today. But it is at times difficult to wait for the evidence to develop which will be (hopefully) more definitively supportive of this approach.
We have, after all, faced similar controversy with respect to prostate cancer screening.
We have known that the death rates from prostate cancer have been decreasing. Although it would appear that prostate cancer screening is responsible for this decline in mortality, not everyone is convinced. There is a clinical trial in progress which we hope will answer the question definitively.
As a result, several major national associations and organizations do not recommend routine prostate cancer screening. Instead, they say that the test should be offered to men along with information that will help them understand the benefits and the harms of prostate cancer screening, based on the best available evidence that we have today.
I suspect that is where we are heading with respect to lung cancer screening based on today’s report in the New England Journal.
Yes, there appears to be a real benefit in terms of survival for those screened according to the standards and protocols set up by these investigators.
No, not everyone would be eligible for screening based on the standards set up in this program.
But if you read or hear about the study, and if you read this blog and feel that you are interested in getting screened, and if you have a reasonable history of smoking (there is no guideline to tell you what the “right” history is where you would benefit from screening) which would put you at a high risk of lung cancer, then you should talk with your health care clinician about what your next steps would be. (This is consistent with the current recommendations of the American Cancer Society.)
But we can’t tell you at this time what the “correct” smoking history would be for you to be screened, and we can’t tell you what the right age is for you to be screened, and we can’t tell you how often you should be screened (aside from expense for these scans, there is the other question about the amount of radiation you might be exposed to, especially if you were 50 years old and decided to get a scan every year. We also don’t know what the best interval is between scans which has the best chance of picking up a lung cancer at an early stage).
There is undoubtedly going to be much discussion and dissection of the results of this study over the next several months. It is premature at this point to say whether any organizations such as the American Cancer Society are going to change their current guidelines regarding lung cancer screening as a result of this report. That will take time and expert consensus.
But there is no question that this well-done study will have a significant impact on the discussions and decisions that will be made by people at risk for lung cancer, their families and their clinicians.
All of us would welcome the opportunity to reduce deaths from lung cancer.
Collectively, the experts have to guide us on the next steps regarding screening for lung cancer.
The sooner we develop that information, the sooner we can provide needed guidance to the millions of smokers and former smokers in this country and around the world who will be anxiously awaiting our recommendations.
Please note: I am posting this from an airport with a poor internet connection. In an effort to be timely with this blog (the embargo lifted at 5PM, I will be adding links at another time.