Lung nodules are small, roundish growths found in the lungs, generally measuring less than three centimeters in diameter. These formations are common, often discovered by chance when individuals undergo imaging scans for unrelated medical reasons. While the vast majority, approximately 95%, of these nodules are not cancerous, a careful evaluation is always necessary.
How Lung Nodules Grow
The rate at which a lung nodule changes in size offers a significant clue about its nature. Benign, or non-cancerous, nodules show very little to no increase in size over time.
In contrast, cancerous nodules demonstrate measurable growth. These growths can double in volume, on average, every four months. The actual doubling time for cancerous nodules can vary widely, ranging from as quickly as 25 days to as slowly as 15 months. A nodule that exhibits no growth over a period of two years is considered to be non-cancerous.
Other Clues for Nodule Assessment
While growth rate provides strong indications, other characteristics and patient factors also contribute to a comprehensive assessment of lung nodules. The initial size of a nodule is an important consideration, as larger nodules are more frequently associated with malignancy. Nodules exceeding one centimeter in diameter are viewed with greater concern.
The shape and borders of a nodule raise more suspicion for cancer compared to those with smooth, well-defined edges. A patient’s age plays a role, with individuals younger than 40 having a higher likelihood of benign nodules. A history of smoking significantly increases the probability of a nodule being cancerous, and nodules located in the upper regions of the lung carry an elevated risk of malignancy.
Following Up on Lung Nodules
Once a lung nodule is identified, medical professionals initiate a monitoring strategy. This process involves a series of follow-up imaging tests, such as X-rays or computed tomography (CT) scans. These scans are performed at specific intervals to observe any changes in the nodule’s size, shape, or other characteristics.
The frequency and duration of these monitoring scans depend on the initial assessment of the nodule’s risk factors. If the monitoring reveals concerning changes, or if initial characteristics strongly suggest malignancy, a biopsy may be recommended. This procedure involves taking a small tissue sample from the nodule for microscopic examination, which provides a definitive diagnosis of whether the nodule is cancerous or benign.