Advances in medical imaging have made screening for lung cancer more accurate in recent years. The traditional chest X-ray may be used for a routine physical evaluation, but more detailed tests now help radiologists, oncologists, and surgeons make an accurate diagnosis when a mass on a patient’s chest is detected, and then determine the best possible course of treatment.
On this episode of Kentucky Health, Dr. Wayne Tuckson speaks with a thoracic surgeon from the metro Louisville area about several effective techniques for diagnosing a mass on the chest, and about how improvements in diagnostic techniques can lead to better patient outcomes.
Dr. Michael Bousamra is head of thoracic surgery at Baptist Health Floyd Hospital in Floyd County, Indiana, across the Ohio River from Louisville. He is also an associate professor with the University of Louisville’s School of Medicine in the department of cardiovascular and thoracic surgery.
Bousamra says that both Medicaid and Medicare administrators advocate for CT scans when screening a patient’s chest, as CT scans are more accurate than X-rays when testing for an indeterminate mass.
“Not every spot is a cancer,” he says. “The smaller they are, the more likely they are to be benign, not cancer. And the larger they are, in general, in broad strokes, the more likely they are to be cancer.”
Accurate Imaging Tools Lead to Better Diagnoses
The increased sophistication and power of a CT scan means that many spots will be detected that turn out not to be cancer, Bousamra says. He presents a slide showing a CT scan of a patient’s chest. It reveals a large mass on the right side of the patient’s lung. Bousamra compares it to another slide of the same patient’s chest from two months prior.
“Armed with this information, we are pretty confident that the spot on the lung is not cancer,” Bousamra says, “because it just wouldn’t develop that quickly. Pneumonias and other types of infections can develop quickly. But if you were just to look at the mass on the left hand side (without comparing to a previous slide), it looks like lung cancer.”
In the Ohio Valley, a lot of people are susceptible to histoplasmosis, a fungal infection that is common to the region and is inhaled. Histoplasmosis has many characteristics of lung cancer; it can spread through lymph nodes, and often requires biopsy to diagnose and surgery to treat.
“The common colloquialism is ‘Ohio Valley Fever,’ and that’s an infection of histoplasmosis where a person gets a rather prolonged illness with fevers, chills, sweats, and perhaps a persistent cough,” he explains. “That often leads to a chest X-ray. And, it’s probably the most common differential that I am brought to distinguish is, is this a lung cancer, or is this a nodule in the lung that is histoplasmosis or something similar to it?”
Other clues Bousamra looks for when examining a chest mass are its color (solid white means that the mass is heavily calcified, and therefore benign) and the shape of the mass wall. “If something is a cyst, with a very thin wall, and maybe has some fluid in it, that’s more likely to be benign,” he says. “Whereas cancers have a thick, shaggy wall.”
Bousamra presents another slide showing an irregularity in the patient’s left lung. He describes the area as indicating the presence of pleural effusion (excess fluid). This could be a result of several maladies, he says, especially pneumonia. Or, it could be evidence of cancer.
To help determine the root cause of the fluid buildup, the doctor would ask about the patient’s medical history, tabulate the symptoms, check for an elevated white blood cell count, which can indicate an infection, and determine the time course of the disease. He says that any time a patient presents with a slow-building sickness, he becomes more concerned about the possibility of cancer.
“Any nodule that is slowly growing, that makes us worry more about cancer,” he says. “Things that are benign, like an inflammation or a pneumonia, they tend to flare up but then regress back down. So if we follow the growth, and it’s getting smaller, generally we’re pretty reassured that it’s not a malignant process, that it’s benign. But if it’s slowly getting bigger, marching on, that’s what cancers tend to do.”
Following Up: Monitoring vs. Additional Tests
Bousamra says that if a detected mass is very small (“half the size of my pinkie finger”) and has a smooth exterior that is not speculated (spiky or shaggy), then he may elect to monitor its growth before considering further tests. A repeat CT scan will be scheduled for approximately three months later. “We just follow these spots along,” Bousamra says, “and if they stay tiny – and more than 9 times out of 10 they do – we just assume they aren’t cancer, without knowing exactly what they are.”
If the suspicious mass does grow and change over time, the first additional test is usually another CT scan or a full-body PET scan to check other physiological areas of interest (the PET scan also measures metabolic changes in tissue). Then a biopsy of the mass will be performed. Bousamra says that in a relatively new procedure called an endobronchial ultrasound and biopsy, the physician fills up a balloon with fluid, threads it down the patient’s throat via a bronchoscope, and runs imaging tests similar to a fetal ultrasound to inspect lymph nodes.
The final slide shows a person with lung cancer, which is located in a hard-to-find area that an X-ray might miss. Bousamra says that CT scans pick up 95 percent of cancers in the lungs.
Other types of cancers may present in the chest area as well, Bousamra says. Lymphomas may be detected in the large lymph nodes in the center of the mediastinum (chest). Tumors of the thymus, a gland underneath the breastbone, can also develop. Bousamra says that if a cancerous tumor is found in the chest of a child or young adult, it is far more likely to be a lymphoma or cancer of the thymus than lung cancer, which largely strikes older individuals with a long history of smoking.
If a malignant lung cancer is found, Bousamra says that “you would want to have a scan that includes the liver, to make sure that there’s nothing suspicious there, because that’s a common place where lung cancers can spread. And then finally, you quiz the patient about central nervous systems, or get a brain MRI, or both, because lung cancers are famous for spreading to the brain.”
Bousamra says that a promising, experimental method he and colleagues are continuing to develop involves analyzing a patient’s breath to determine if cancerous cells are present.
“We’ve discovered that cancers give off a variety of chemical compounds called volatile organic compounds,” he explains. “In my research and work with collaborators at the University of Louisville, we’ve identified four compounds that are relatively specific for cancer. At least on initial studies, in studying approximately 400 subjects, the test picks up cancer at about a 95 percent rate. Now, it needs to be refined and studied further, but we hope that one day it can be used actually clinically, to help doctors differentiate between spots on the lung that are or are not cancer.”
