When reading about health topics, you might come across the word “neoplasm,” which is actually another word for tumor. A tumor is a mass made up of cells that have divided abnormally. While being diagnosed with a neoplasm or tumor sounds ominous, it’s important to know that not all are cancerous. 

“Tumors are growths in any part of our body,” says Xavier Llor, MD, PhD, a cancer geneticist and gastroenterologist who is the co-director of the Smilow Cancer Genetics & Prevention Program. “The body has a system of checks and balances in each of our organs that's in perfect equilibrium, but when that gets broken, a growth that is not controlled by our body can develop. Sometimes those growths are benign [noncancerous], but some will be malignant, or cancerous.” 

Tumors grow in solid tissues such as organs, joints, and bones. Sometimes, you may be able to feel a tumor. Other times they are only detectable with imaging tests such as an MRI, CT scan, PET scan, endoscopy, or ultrasound. In either case, a biopsy is often needed so that it can be evaluated under a microscope to determine if it is a benign, precancerous, or malignant tumor. 

The millions of cells within our bodies go through a life cycle. They reproduce and replenish themselves as old ones die or become defective, usually without issue. 

But sometimes things don’t go perfectly. Instead of eliminating old cells or cells that have sustained damage to their genes (DNA), these flawed cells may start dividing rapidly and pass along abnormal copies of themselves, over and over again. Eventually this forms a mass or tumor that can be benign or malignant.  

Often tumors are not cancerous; usually noncancerous tumors are not serious, even though the cells in them are abnormal. Cells that are abnormal but not cancerous are what doctors called “organized”—when the pathologist evaluates a biopsy of the tissue under a microscope, the cells look normal and are well-arranged. Also, unlike with malignant cells, the ones in benign tumors don’t usually invade nearby tissues.

Tumors can go through changes (hyperplasia and dysplasia) on the way to becoming cancerous, and these are called precancerous tumors. Therefore, benign tumors may be removed for three reasons: to confirm they are actually benign, to ensure they don’t have a chance to become cancerous, or to relieve symptoms if the tumor is in a place that causes problems or pressure, such as a benign brain tumor. Benign tumors generally do not grow back.  

The more abnormalities (DNA changes) in tissues, the more likely they could become cancerous down the line. While most benign tumors cause no harm, ones that grow in the brain, although not cancerous, can be life-threatening if not removed. 

Malignant tumors are cancerous, meaning their cells have sustained several abnormal changes to their DNA. They begin invading neighboring cells, multiplying and dividing at a very fast and out-of-control rate. Each time they copy themselves, they pass along their defects, and cells become more and more abnormal as time passes and they spread further. 

While the body’s immune system does repair or remove abnormal cells (a process called apoptosis), cancerous cells are able to slip by undetected and take over the immune system they bypassed.

Not only does the invasive nature of malignant cells cause them to spread to nearby tissues, malignant cells can spread in another way, too—by traveling through the bloodstream. If one or more cells slough off from a primary tumor (where the cancerous cells first appeared), those cells can be transported by blood, allowing them to form a new malignant tumor in a completely different location. 

This is called metastatic or secondary cancer; although located outside the area it originated from, a secondary or metastatic tumor is made up of cancer cells from the primary cancer site. 

Tumors are sometimes detected during a screening test such as a mammogram, prostate-specific antigen test, or colonoscopy. Screenings are recommended for common cancers, explains Dr. Llor, including breast cancer and colorectal cancer, starting at particular ages. Screenings are also recommended for some patients for lung and prostate cancers and skin cancer for people with specific risk factors. National guidelines that are regularly reviewed and updated determine who cancer screenings are recommended for and at what age screening should begin. 

Occasionally, cancer is discovered when a patient is having imaging done for another reason. This is called an incidental finding.

If a tumor is located close to the surface of the skin, you may be able to feel the mass or lump with your fingertips. Other times, though, tumors grow in the organs, for example, where they cannot be felt, and they can go undetected until symptoms such as fever, fatigue, bleeding, or pain, among others, develop.

If cancer is suspected, doctors will perform the following diagnostic tests to gather more information:

• Lab work to check the levels of certain chemicals or hormones in the blood, urine, and other bodily fluids. These fluids are evaluated by a pathologist. Levels that are too high or too low may be a marker of cancer. 
• Diagnostic imaging allows physicians to see inside the body, including in internal organs, in order to check for cancer. Common imaging studies include MRI, CT scan, ultrasound, PET scan, and X-ray. A radiologist will evaluate the imaging and diagnose a tumor, if found, as likely cancerous or benign.
• Biopsies are performed in order to obtain a tissue sample of a tumor that can be evaluated under the microscope by a pathologist. Depending on where a tumor is located, a biopsy can be performed during surgery or through a procedure called a stereotactic biopsy, in which a needle is inserted into the targeted area, using an X-ray image as a guide. A pathologist examines the tumor and determines if its cancerous. 

The following treatment options may be used alone or in combination to treat tumors:

• Surgery. Benign tumors can be surgically removed. For patients who are not well enough for surgery or for cases where the tumor is in a difficult-to-reach location, another treatment option may be used. 
• Chemotherapy. These drugs are administered to kill cancer cells and/or to stop their growth and spread.
• Radiation Therapy. Targeted beams of radiation can kill cancer cells. New technology allows pinpoint accuracy, with the goal of minimizing radiation exposure to healthy surrounding cells.
• Ablation. Doctors can reduce or eliminate tumors by treating them with extreme cold or heat. 
• Embolization. Sometimes doctors are able to stop the flow of blood to a tumor, which causes it to wilt and die off. Sometimes this is done in combination with chemotherapy or immunotherapy delivered directly to the tumor.
• Hormonal Therapy. For tumors that feed off hormones (estrogen or androgen, for example), doctors can prescribe hormone-suppressing medications.
• Immunotherapy. Immunotherapy drugs either help boost the immune system so that it has more strength to fight cancer cells. Or, they can target and destroy certain proteins, or receptors, on cancer cells to prevent them from outmaneuvering the immune system.

At Yale Medicine, our radiologists and pathologists specialize in cancer types so that you have the most experienced, highly skilled eye looking at your diagnostic imaging or biopsy.  

If a neoplasm is determined to be cancerous, Yale Medicine doctors hold weekly meetings called tumor boards where 30 specialists review active cases and determine the most effective treatment option for each patient. In many cases, tumors are evaluated for the specific gene mutations that can make them unique and this allows for targeted therapies that are adjusted according to the best chance of response. This is the principle of precision medicine that is commonly applied at Yale Cancer Center and Smilow Cancer Hospital.