Seeing the term “cancer dot” on a scan report or hearing it from a doctor can be unsettling. This informal phrase is how patients often interpret small, suspicious findings on their medical images, which can be a starting point for many questions. The reality is that these “dots” are the first step in a detailed diagnostic journey. Understanding what these dots are, how they are found, and what they signify provides clarity.
Translating “Dot” into Medical Language
In a clinical setting, the term “dot” is replaced with more precise medical language to describe an area of abnormal tissue. A “lesion” is a general term for any damage or abnormal change in the tissue caused by disease or injury. If the lesion is a small, distinct, and well-defined growth, it is often called a “nodule.” Pulmonary nodules, for example, are small masses of tissue in the lung that appear as round, white spots on a chest X-ray or CT scan.
These nodules are quite common, found in up to half of all lung CT scans, and most are benign. A nodule is defined as being 3 centimeters (about 1.2 inches) in diameter or smaller. Should the growth be larger than 3 centimeters, doctors will instead use the term “mass.”
These terms are descriptive, not definitive diagnoses, and categorize the finding based on characteristics like size and shape. The presence of a nodule or mass can be due to a variety of noncancerous causes, like infections that cause inflammation or scar tissue. For instance, small clumps of cells called granulomas can result from past infections and appear as nodules on a scan.
How Doctors Find These Spots
To visualize these spots within the body, doctors rely on advanced imaging technologies. One of the most common tools is the computed tomography (CT) scan. A CT scanner takes a series of X-ray images from different angles and uses a computer to create detailed, cross-sectional pictures of your organs, bones, and soft tissues. This allows doctors to see a potential tumor’s size, shape, and location.
Another powerful technology is magnetic resonance imaging (MRI). Instead of X-rays, an MRI uses a powerful magnetic field and radio waves to generate highly detailed images. It is useful for creating clear pictures of soft tissues like the brain, spinal cord, and internal organs, helping doctors distinguish between tissue types.
A positron emission tomography (PET) scan works differently. Before the scan, a patient receives an injection of a radioactive substance, often a type of sugar called FDG. Because cancer cells are more metabolically active and consume more glucose than normal cells, they absorb more of this tracer. The PET scanner detects this accumulated radioactivity, which shows up as bright “hot spots” on the images.
Often, PET and CT scans are performed at the same time (PET/CT). This approach combines the functional information from the PET with the anatomical detail of the CT for a more accurate assessment.
Determining if a Spot is Cancerous
Once a spot is detected on a scan, the next step is to determine whether it is benign (noncancerous) or malignant (cancerous). Radiologists and oncologists analyze several features of the spot on the images to assess its likelihood of being cancerous.
Analysis Through Imaging
Characteristics used to evaluate a spot include its size, as larger nodules are more concerning, and its shape. Spots with irregular or “spiky” borders are more suspicious than those with smooth, rounded edges. The density of the spot is also evaluated. On a CT scan, a solid-looking nodule has different implications than one that is hazy or “ground-glass” in appearance.
Certain patterns of calcification, or calcium deposits, within a nodule can also suggest it is benign. In many cases, if a spot is small and doesn’t have overtly suspicious features, a doctor may recommend “watchful waiting.” This involves performing follow-up scans over several months or years to see if the spot grows or changes, as growth is a significant indicator of cancer.
Confirmation with a Biopsy
Imaging alone cannot provide a definitive diagnosis, so the most reliable confirmation is a biopsy. A biopsy is a procedure where a small sample of suspicious tissue is removed from the body. Depending on the spot’s location, a doctor might use a needle guided by a CT scan or a thin tube passed down the throat to collect the sample. A pathologist then examines this tissue under a microscope to confirm or rule out a cancer diagnosis.
The Significance of Multiple Spots
Finding a single spot on a scan is one scenario, but discovering multiple spots raises different concerns. When numerous spots are present, especially across different organs like the lungs and liver, it often points to the possibility of metastatic cancer. Metastasis is the process by which cancer cells break away from the original, or primary, tumor and travel to other parts of the body to form new tumors.
These new tumors are called metastases or secondary tumors. Even if cancer spreads to a new organ, it is still identified by its primary site. For example, if breast cancer spreads to the lungs, it is called metastatic breast cancer, not lung cancer. This distinction is important because the treatment is determined by the type of cancer where it originated.
The presence of multiple spots is generally considered a more advanced stage of cancer, often classified as stage IV. The appearance of multiple lesions helps doctors stage the cancer, which describes its location and spread. This staging information is fundamental for developing an appropriate treatment plan.