Dr. Yu obtained her MD/PhD from the University of Massachusetts Medical School and completed her Internal Medicine residency and Chief Internal Medicine residency at Tufts Medical Center. She went on to complete Pulmonary and Critical Care Fellowship at the University of California San Francisco and Interventional Pulmonology Fellowship, a joint collaborative program with UCSF, the Palo Alto Medical Foundation, and El Camino Health. A member of Palo Alto Medical Foundation, Dr. Yu specializes in minimally invasive bronchoscopic procedures, which she performs at El Camino Hospital in Mountain View. Her research interests include lung cancer diagnosis and management and interventional pulmonology device development.
Basics of lung anatomy
Your lungs are two spongy organs in your chest, one on each side. Your airway starts with your main windpipe in your throat called the trachea. Then like an upside down tree, it divides into the right and left side and then divides into smaller and smaller branches. Ultimately, the branches terminate in little structures called the alveoli. That's where we are able to exchange oxygen and carbon dioxide every time we breathe. Lung cancer typically develops in the lining in this airway or in the alveoli themselves.
Lung cancer is the most common cause of cancer death worldwide. There were 1.8 million deaths in 2020 alone. It doubles the next leading cause of cancer death, which is colon and rectal cancer. It mainly occurs in people older than 65. The average age of diagnosis is 70 years old.
There are two main types of lung cancer: non-small cell lung cancer and small cell lung cancer. Non-small cell lung cancer is more common. There are other types of lung cancer that are much less common and I haven’t included them on this list.
The leading risk factor for lung cancer is cigarette smoke. 80% of lung cancer deaths are believed to be due to smoking. Cigars and pipes are also risk factors, but not as much as cigarettes. There are a lot of other risk factors, some that are modifiable and some that are not. Things that we cannot change are our genetics, family history, and age. Things that we can change are exposures to things like asbestos, radon gas, and radiation. Also exposure to pollution matters: both indoor and outdoor pollution.
A question that comes up a lot with my patients is asbestos exposure. Generally, asbestos exposure relates to occupational exposure. A lot of houses these days have asbestos in them, but as long as they are in good repair and undisturbed, it's not increasing your risk of lung cancer.
Lung cancer symptoms can be pretty non-specific. They can include a persistent cough, chest pain, and shortness of breath. Sometimes there’s wheezing, coughing up blood, and fatigue. Some symptoms that can be concerning for any type of cancer are unintentional weight loss, fevers, chills, and night sweats. Also sometimes with lung cancer you keep having pneumonia in the exact same spot or you have enlarged lymph nodes in your chest. Our lymph nodes are like the gutters of our body and we have over 600 in our head and neck. Any time there’s infection, inflammation, or cancer, lymph nodes can become enlarged. So enlarged lymph nodes in your chest don't necessarily mean you have cancer, but should alert doctors that something is going on.
Lung cancer evaluation is important because the prognosis and treatment depend directly on tumor size and spread at the time of diagnosis. Lung cancer is characterized in stages 1-4: stage 1 is the most local while stage 4 is the most advanced and has spread to other parts of your body. To help with lung cancer evaluation, lung doctors play a very big role. We can help with smoking cessation counseling, diagnosis, staging, and treatment of lung cancer. And once cancer therapy has begun, we can also help manage any side effects or complications from lung cancer treatment that are related to your lungs.
How do we screen for lung cancer?
We use an imaging technique called low dose computed tomography to screen lung cancer. The patient lays down on a table and goes through this donut shaped scanner to take pictures of the lungs. There are certain criteria that you should meet in order to be screened for lung cancer. The screening criteria include being aged 50-80, active smoking or have quit within the last 15 years, and having smoked at least 20 pack years. Pack years are calculated by multiplying the number of packs per day by the number of years you've smoked. So 20 pack years can be half a pack per day for 40 years or 1 pack per day for 20 years.
How do we diagnose lung cancer?
Generally, imaging tests are the first step. X-rays are a common first imaging test we do, but it doesn't provide a lot of details. If we see something concerning on an X-ray, then we will get a CT scan. Another type of imaging study we can do is a PET scan, which stands for positron emission tomography. In this scan, the patient is injected with radioactive sugar, and anything in the body that is metabolically active will take up that sugar. PET scans are very helpful but do not differentiate between things like infection, inflammation, or cancer. All three of those things will take up sugar and be positive on a PET scan.
Ultimately, we have to do a tissue biopsy to confirm if something is cancer or not. There are three different ways generally to do tissue biopsies. One is with interventional pulmonology. The way we do biopsies is using a long tube with a camera in the end that goes into your mouth and into your lungs. We're able to go into your lungs and take biopsies from the inside. Another way to do biopsies is with interventional radiology. They do biopsies from the outside in. The most invasive way to do a biopsy is through surgery. Surgeons will make small cuts on your chest wall and use instruments to cut out a larger piece of your lung.
How do we treat lung cancer?
Surgery is always recommended if possible. Our surgeons can do this with minimal cuts to remove the cancer. The different sizes of lung tissue that surgeons can cut out depend on the extent of tumor. Another treatment option is radiation therapy. Radiation therapy is very good at controlling lung cancer so it doesn't spread.
If cancer has already spread and is not amenable to surgery or radiation therapy alone, then chemotherapy is generally recommended. Chemotherapy is given intravenously (IV), usually once a week for multiple weeks.
There have been recent advancements in lung cancer treatment including targeted gene therapy. Based on the tissue biopsy we obtain, we can do special analyses to look for specific gene mutations in the tumor. If the tumor has a specific mutation, we can give that targeted gene therapy medication. The benefit of targeted gene therapy over chemotherapy is that targeted gene therapy can cause less damage to normal cells. Targeted gene therapy is also in the form of pills instead of IV. That's why it's so important for us to be able to get tissue in order to do these analyses. There’s also a class of medications called immunotherapy. Basically, immunotherapy works to enhance your body's own immune system to fight the cancer. Immunotherapy is generally given through IV.
In summary: to reduce your risk of lung cancer, please stop smoking! If you qualify, please get a low dose CT to screen for lung cancer. You can ask your primary doctor or lung doctor about getting the scan done.