I am sure all of you have heard the phrase “A picture’s worth a thousand words!” I first heard it from my undergraduate biology professor, who always reminded us that each time we looked at an anatomy image in Grey’s Anatomy, we would learn something new. Well, little did I know that I would be using the same phrase in the context of lung cancer screening and computed tomography (CT) screening.
CT scans use low-dose radiation that passes through your body to capture images. CT scan images are like slices of bread—when stacked up, you have the whole loaf: a picture from the outside of what’s happening inside your lungs. Doctors currently use CT scans to screen for lung cancer in individuals who are at high risk of developing lung cancer. They also use them to help determine whether a treatment is working; these CT scans are known as follow-up scans.
I recently read an article that talked about concerns of radiation exposure from too many scans. We have also heard of similar concerns from our survivor community. To learn more about how CT scans are conducted and their benefits and risks in the diagnosis and treatment of lung cancer, I sat down with Lawrence Schwartz, MD, Chair, Department of Radiology, Columbia University Medical Center, and Service Chief and Attending Physician, New York-Presbyterian Hospital. He is also a member of LUNGevity’s Scientific Advisory Board.
Dr. Schwartz is an expert in the imaging of lung cancer and a pioneer in radiomics, a field of research that aims to learn about the molecular characteristics of a cancer from a scan image. We discussed how doctors have refined the use of CT scans to ensure that there is maximum benefit and minimum risk to individuals.
LUNGevity Foundation: CT scanning has become an integral part of lung cancer screening and also monitoring how patients respond to different treatments. What are some of the benefits and risks associated with CT scans?
Dr. Larry Schwartz: Before discussing the benefits and risks of CT scans, I think it’s important to point out that we use low-dose CT scans (hence the name LDCT), which means that we are now able to get the same quality of image but use much less radiation. As a doctor, I understand that patients are afraid of unnecessary radiation exposure. This is precisely the reason why researchers have been hard at work to solve this problem! Now, thanks to improvements in the actual scanning machine as well as better computer software that analyzes the image, we are able to take excellent images at lower doses of radiation. Another point to keep in mind is that, since our lungs are filled with air, we can get away with much lower doses of radiation since the radiation does not have to go through many layers of tissue.
When doctors recommend CT scans—either for diagnosing lung cancer or for checking how a patient is doing on a treatment—they do it with good reason. And that reason is that the benefits from a CT scan far outweigh the risks of radiation exposure.
For early detection of lung cancer, a CT scan is used for high-risk individuals. The probability of detecting lung cancer outweighs any risks associated with the scan—because if you catch the lung cancer early enough, you can treat it at an earlier stage, too. And the same benefit is associated with follow-up CT scans. After a patient starts treatment, regular scans help the doctors catch the cancer if it starts growing and can adjust or change the treatment. Doctors always take into account how the patient is feeling on a new treatment when ordering new CT scans.
LF: In addition to early detection and treatment monitoring, what other information can we learn from CT scan images?
LS: Many people find this hard to believe, but scan images are very personalized to each patient. They are definitely not just black and white images that tell a doctor whether someone has lung cancer or if the cancer has grown. They can tell us about the individual makeup of the cancer. That’s what the field of radiomics is about.
For example, CT scan images of lung cancer with metastasis to the adrenal gland would look very different from cancer with bone metastasis. Also, lung cancers that are positive for the EGFR mutation and diagnosed in nonsmoking women look less solid in CT scans than other types of lung cancer. We are still learning how best to use the field of radiomics—to answer questions such as: Can images predict if a cancer is likely to grow fast? Can radiomics images guide us to the right location for a biopsy if the cancer has progressed?
Thanks to Dr. Schwartz, I can say that a CT scan image is definitely worth a thousand words.
Dr. Basu Roy is LUNGevity's Director of Translational Research Programs/Director of Patient FoRCe. 