As you may know by now, November is Lung Cancer Awareness Month and Austin Air has been participating by spreading the word. We’ve outlined how you can avoid lung cancer (#1: QUIT SMOKING!), why it’s an important cause (lung cancer research is seriously underfunded), how you can participate (donate, discuss, volunteer), as well as symptoms to look out for. In our final installment of this series, we’re going to talk about screening.
Women are encouraged to pay attention to how their breasts look and feel so they can report any changes to a doctor. The same goes for men and their testicles. Due to the fact that the lungs are an internal organ, they are obviously more difficult to check. Most lung cancer patients receive a diagnosis after displaying symptoms of the disease, usually after it has had time to progress and spread throughout the body. This disadvantage is huge but improvements have been made in our understanding of the importance of screening for lung cancer and the most effective method, thanks in part to the National Lung Screening Trial.
By definition, screening is different from testing someone who is presenting symptoms of the disease. If a patient shows signs of illness, they are also tested but it isn’t considered screening. Meanwhile, the aim of screening is to find cancer before it advances to the point where they can exhibit symptoms. In fact, the American Cancer Society currently recommends for patients to be in fairly good health before being screened for lung cancer. The thinking is that only patients who are relatively healthy will be able to benefit from the early diagnosis. This may seem counter intuitive, but it’s because treatment for lung cancer is somewhat invasive. The patient would need to be able to withstand surgery and any complications that may arise. Anyone who requires oxygen therapy at home would probably be unable to survive having part of their lung removed. Basically, screening won’t be effective for patients who can’t survive the treatment.
Beyond being in relatively good health, patients should only be screened if they meet all of the following criteria:
- Aged between 55 and 80 years
- Currently smoke, or quit smoking within the last fifteen years
- Have a smoking history of at least 30 pack-years
A pack year is used to calculate how much a person has smoked over their lifetime. The number is determined by taking the number of packs of cigarettes a smoker had per day and multiplying it by the number of years they continued the habit. One pack a day for one year would be one pack year. One pack year is also half a pack a day for two years or two packs a day for half a year.
The National Lung Screening Trial (NLST) had 53,454 participants who were current or former smokers who had at least thirty pack years behind them without any symptoms or history of lung cancer. The aim of the NLST was to compare two methods for detecting lung cancer – standard chest X-rays or spiral CT scans, formally known as low-dose helical computer tomography. Standard X-rays can only produce a single image of the whole chest with the anatomic structures overlying each other, while spiral CT scans can obtain a multiple-image scan of the whole chest. Over a seven year observation period, the study found that those who received the spiral CT scan were 15-20% less likely to die of lung cancer than patients who were simply X-rayed.
There were three rounds of screening. CT-scanned patients tested positive on an average of 24.2% versus 6.9% of X-ray tested patients. Positive screenings always led to more testing. Adenocarcinomas, a type of non-small cell lung cancer which accounts for approximately 40% of lung cancer cases, and squamous cell carcinomas were the two most frequent types to be detected at the earliest stage by the CT scans over X-rays. Unfortunately, CT scans did not have an advantage in the detection of the more aggressive small-cell lung cancers at their early stages.
Unfortunately, metal implants in the back and chest, such as metal rods in the spine or pacemakers, have been known to disrupt X-rays and diminish the quality of CT images. Therefore, people with metal implants would not benefit from being screened.
There is another, very important reason why CT scanning isn’t recommended for everyone – there are very real health risks to excessive CT testing. CT scans expose patients to ionizing radiation, which is a known human carcinogen. As of December 2011, the Institute of Medicine published a report which stated that breast cancer is the cancer most likely to develop as a result of routine exposure to ionizing radiation. Most Americans are exposed to ionizing radiation from natural sources in the environment, with medical imaging (particularly CT scans) accounting for the other half. That isn’t to say testing should be avoided completely. The risk of a test for cancer potentially causing cancer dictates that such scanning should be avoided if it won’t be helpful.
Proper screening is an important tool in the battle against lung cancer. Regular screening, such as mammograms or colonoscopies, are routine for other cancers but it wasn’t until January 1, 2015 that lung cancer screening was covered by most health insurance plans. People without insurance who fit the criteria for screening may be able to receive free screening and preventive services through local and state agencies. This brings new hope to the battle against lung cancer. If you know anyone who fits the criteria, encourage them to speak to their doctor about getting screened. If you’re still not sure if screening is right for you, the American Lung Association Lung Force website has a helpful quiz you can take to find out.
Any readers who missed the chance to participate in Lung Force Day – the fund drive by the American Lung Association and the Cancer Treatment Centers of America – on November 17th can still help by getting the word out.
