Tumor Or Cancer? Why You Must Know The Difference

All tumors are not cancer.  Some cancers are not tumors.  This article focuses on the different terminologies in oncology, and how awareness of the various terms prevents misconceptions.

Medical jargon can be confusing.  Different terms can mean the same thing, but sometimes with subtle differences.  Misinterpretation of terminology can have unintended and potentially serious consequences.  It is important therefore to clearly understand the meaning of the terms used during a medical discussion.

A tumor (in Latin “tumor” means swelling) is an abnormal growth of tissue. Some people may use other words as an alternative to “tumor” including “neoplasm”, “lesion”, “growth”, “swelling”, “lump” or “mass”.  There are two types of tumors – benign (noncancerous) and malignant (cancerous). Some cancers affect blood or lymph cells, and therefore there may no obvious “tumor” (swelling) in these cases.

Benign (Non-cancerous) tumors Malignant (Cancerous) tumors
Grow slowly Grow rapidly
Rarely life-threatening Potentially lethal
Do not spread Spread to distant organs
Do not invade surrounding tissues Invade surrounding tissues
Treatment usually simple, or not even required Treatment usually complex
Low chance of recurrence High chance of recurrence


Sometimes, a simple physical examination by a doctor is sufficient to determine if a tumor is benign.  At other times it is not possible to tell the difference, and a  biopsy is required to know whether a tumor is benign or malignant.

Confusion between the terms tumor (or growth or neoplasm or lesion) versus cancer (or malignancy or carcinoma) is common.  People hesitate to seek clarifications or they make assumptions.  This can lead to unnecessary anxiety and can sometimes be dangerous. Here are some examples:

  1. Oh no, I have Cancer”: The word “Tumor” implies “Cancer” to some people. I have spent many hours explaining to people with harmless benign conditions that they do not have cancer and that they are not going to die!  Examples include fibroadenomas in the breast, fibroids in the uterus, functional ovarian cysts, and lipomas under the skin.  Many benign tumors require no treatment and some can even go away on their own.
  2. Thank goodness I do not have Cancer”: Everyone (including doctors) hesitates to use the word “Cancer”. Doctors may use terms like “tumor” or “growth” in a discussion so as not to upset the patient with cancer.   See this post on disclosing the diagnosis of cancer.  Occasionally, such a patient is inadvertently led into believing they do not have cancer, and delays or avoids treatment
  3. Somebody else was treated differently”: Obviously the treatment for a benign tumor is likely to be different from a malignant one.  But people compare their treatment with that of someone else with a “tumor” in the same organ – “My uncle had a tumor in his colon – his doctor removed it through a colonoscopy.  Why do I need major surgery and chemotherapy?”
  4. My tumor is small – maybe I can wait”: Paradoxically, a benign tumor can enlarge slowly to attain a considerable size without causing much harm to the patient. On the other hand, a malignant tumor not only grows quickly, it also invades and spreads.  Therefore malignant tumors cause symptoms early and can even be fatal before they reach a large size.  Anecdotes of someone who lived for decades with a large “tumor” on their head, or someone whose large ovarian “tumor” disappeared one day, should not dissuade a person with cancer from seeking the right treatment for themselves.
  5. I do not understand the word used for my diagnosis. Tumors are named based on the type of abnormal cell, and there are literally hundreds of types of tumors.  For the layperson, the distinction between benign and malignant tumors may not be obvious from the nomenclature.  For example, a lipoma is a benign tumor, but a melanoma is malignant.  Mesothelioma is an aggressive and dangerous malignancy, but dermatofibrosarcoma is rarely fatal.  It is important to discuss the diagnosis in detail with the doctor to know what kind of disease one is dealing with.

To summarize, one of the most important things to know about a tumor is whether it is benign or malignant.  Complicated medical terminology should not come in the way of a clear understanding of the diagnosis.

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