The Differences Between Tumors and Cancer

It is incorrect to use the terms cancer and tumor as synonyms. Let's see how they're distinguished and why their differentiation is important.
The Differences Between Tumors and Cancer

Written by Josberth Johan Benitez Colmenares, 01 September, 2021

Last update: 01 September, 2021

Most people aren’t aware of the differences between tumors and cancer. This is because in popular and even scientific contexts they are often used interchangeably to refer to the same condition. However, these are terms that aren’t interchangeable and, in this article, we’re going to try to explain why in simple words.

To start with, we’re going to tell you our conclusion: all cancers are tumors, but not all tumors are cancers. With this in mind, we can now get on with discussing just what we mean. To begin, we need to clarify what doctors mean when they talk about cancer and when they talk about tumors. Let’s go a little deeper.

What is cancer?

The differences between tumor and cancer are very evident
Cancer groups together a group of malignant diseases, responsible for a large proportion of annual deaths worldwide.

As the National Cancer Institute (NCI) points out, cancer is a disease characterized by the uncontrolled multiplication of malignant cells that tend to spread throughout the body.

Growth can occur anywhere, although it’s most common in the breasts (breast cancer), lung (lung cancer), prostate (prostate cancer), and colon (colon cancer), among others.

Cancer is caused by the uncontrolled multiplication of cells in a process known as cell division. This process works under a perfect balance – new cells are replaced as others age and die. However, when a patient develops cancer, the process becomes unbalanced and abnormal cells, instead of self-destructing, divide uncontrollably.

This is also known as neoplasia and is a disease with one of the highest mortalities worldwide. For example, and according to the evidence, in 2020 there were an average of 19.3 million new cases and a total of 10.0 million deaths. There are different treatment options, depending on the characteristics of its development, the medical opinions, and the patient’s condition and disposition.

What are tumors?

Tumors are masses of abnormal tissue that develop when cells multiply and grow. As Stanford Health Care reminds us, there are two types: cancerous and non-cancerous. In the first case, it involves cells that are prone to invade other parts of the body and return after eliminating them. In the second, the cells don’t spread and don’t return after eliminating them.

They’re also known as benign and malignant tumors. We also find a third category called precancerous cells. This name refers to tumor formations that can turn into cancer if they’re not treated in time. That is, they aren’t malignant when detected, but their condition can evolve over time.

This last category also has many subcategories. We thus highlight dysplasia, metaplasia, hyperplasia, atypia, and carcinoma in situ. Tumors can be removed surgically, although it all depends on their characteristics and the criteria of the specialist. In certain contexts, a benign tumor can be dangerous for the patient.

4 differences between tumors and cancer

Reading the above insights, you have surely already identified some of the differences between tumors and cancer. We’ve compiled the four most important ones below:

1. Cancer is a disease…tumors can be

As we have clearly shown you, the term cancer refers to a disease. It is always accompanied by the name of the area or organ where it was detected. For example, skin cancer. In contrast, tumors aren’t always a disease; they’re a formation of cells that can sometimes be benign.

2. Cancer is made up of malignant cells, tumors aren’t always

Differences between tumor and cancer include their malignancy
Malignant cells are characterized by their ability to spread to other organs and systems. For example, the lungs are often a common site of metastasis.

To be considered as such, cancer must be made up of malignant cells. That’s to say, of cells that are prone to invade the surrounding tissue and to spread beyond the area where they originate. Tumors can be benign or malignant, so not all reported cases necessarily lead to cancer.

In fact, and contrary to what people believe, around 9 out of 10 developed tumors are benign. The balance is in our favor when it comes to detecting formations that lead to cancer. This is one of the most important differences between tumors and cancer.

3. Cancer can be deadly, tumors don’t have to be

The percentage of cancer deaths depends on the characteristics of the formation, the place of development, and how soon it was diagnosed. According to the World Health Organization (WHO), the deadliest cancer is lung cancer, with an average of 1.8 million deaths each year.

In contrast, benign tumors rarely cause complications in patients. In fact, you can live with them without major problems, as millions of people around the world do. According to Cancer Treatment Centers of America, the most common are fibroids, lipomas, leiomyomas, adenomas, and hemangiomas.

Of course, this doesn’t mean that complications can’t occur. If the tumor grows out of control or grows in an especially vulnerable place, it can interfere with some basic functions of the body. Such is the case of those that grow in the brain.

4. Cancer can lead to metastasis, tumors don’t always

Finally, another difference between tumors and cancer is that malignant cells can metastasize. That is, the cells can spread their place of origin to other parts of the body. When this occurs, the condition isn’t classified as a new type of cancer; the original cancer is said to have metastasized.

In contrast, it isn’t possible for the benign cells that make up most tumors to carry out this spread. Their growth is generally slower and they always remain in the place where they have developed.

So, our conclusion is that we shouldn’t use cancer and tumors as synonyms. Although all cancers are malignant tumors, not all types of tumors are carcinogenic. This distinction should be assimilated in order to avoid shocks when tumors are diagnosed in us or in our loved ones.

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  • Sung, H., Ferlay, J., Siegel, R. L., Laversanne, M., Soerjomataram, I., Jemal, A., & Bray, F. Global cancer statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA: a cancer journal for clinicians. 2021; 71(3): 209-249.