The 6 differences between tumor and cancer

Although awareness has been raised about it, there are still doubts about the differences between tumor and cancer. We show you 6 useful criteria to make the distinction.

Last update: December 11, 2021

Often, most people are unaware of the differences between a tumor and cancer. In part, they do so because doctors or popularizers often use the two terms synonymously. Although of course they share similarities, the truth is that we can establish clear differences. Today we expose you 6 of them so that you know what exactly a diagnosis of this type refers to.

Certainly, the differences between tumor and cancer are not well known to patients. This can cause uncertainty, fear or anxiety when hearing one or another term after a consultation with the specialist. Without the intention of replacing their judgment, in the following lines you will find out what they mean when they talk about one or another diagnosis.

Main differences between tumor and cancer

Before describing the main differences between tumor and cancer, it is right that we advance the thesis that will be sustained during this trip: all cancers are tumors, but not all tumors are cancers. In essence, this sentence sums up very well the 6 differences that we have chosen below. Let us analyze them carefully.

1. Intrinsic characteristics

Both tumor and cancer refer to disproportionate cell growth. In this they are similar. They are not in the intrinsic characteristics of these cells. When a pathologist looks at the samples under a microscope after the biopsy, they can find these characteristics and group them as one or the other.



A tumor is the disproportionate growth of normal cells. There was a lack of control in their daily functioning, they began to grow and resulted in a lump. Analysis shows that DNA and structure appear normal. When so, it is classified as a non-cancerous tumor (or Benign tumor).

On the contrary, cancer cells are abnormal.. Under the microscope the shape or size of these is different. Researchers believe that it only takes 4 mutations for a cell to evolve from normal to abnormal. According to the National Cancer Institute, this variation alters its behavior. Let’s see some examples:

  • They can trick the immune system into not detecting them as abnormal (when they don’t destroy themselves, the system identifies and removes them).
  • They convince the immune system that it protects them and encourages their abnormal growth.
  • They grow independently of external cues telling them to do so.
  • They ignore external signals telling them to stop growing or to self-destruct (apoptosis).
  • They order the blood vessels to grow around them. This way they eliminate waste and ensure oxygen and nutrients to grow more.
  • They have chromosomal abnormalities.
  • They can survive and grow on different nutrients than normal cells use.

When the cells detected respond to several of these characteristics, it is said to be a cancerous tumor (or malignant tumor). As you see, the difference is given by its characteristics and behavior. Still, they share the disproportionate growth. For this reason, we point out that all cancers are tumors, but not all tumors are cancers.

2. Growth

When tumors grow disproportionately and rapidly, it is likely that it is actually a case of cancer.

As Stanford Health Care reminds us, in cell growth we find another difference between tumor and cancer. Indeed, benign tumors are generally slow growing; while malignant tumors do it in an accelerated way. This is due to the characteristics that we have already discussed.

A malignant tumor can grow in a couple of weeks or months what a benign tumor would take years to grow. This is why not all benign tumors are operated on, especially when they are very small and are not housed in a compromised area (the brain or ovaries, for example).

3. Evolution

The next useful distinction to distinguish between tumor and cancer is the character of evolution. Cells from benign tumors do not spread. That is, they remain grouped in one place without invading fenced tissue. They can grow, but they will always grow within the same area.



The same does not happen with the cells of cancerous tumors. These tend to spread through the surrounding tissues, and even travel to other parts of the body. This process is known as metastasis and its peculiarity is that the cell that reproduces in another place is identical to the original one.

Due to this last characteristic, a metastatic cancer is named after the original or primary cancer. For example, if a woman with breast cancer has metastasized to the lung (cells have spread to this site), it is not classified as lung cancer. It is cataloged as metastatic breast cancer.

4. Dangerousness

As you’ve already guessed, cancer cells are in greater danger than non-cancer cells. According to the World Health Organization (WHO), in 2020 there were an average of 10 million cancer-related deaths. The most lethal for that year were the following:

  1. Lung: 1.8 million deaths.
  2. Colon and rectum: 935,000 deaths.
  3. Liver: 830,000 deaths.
  4. Stomach: 769,000 deaths.
  5. Mother: 685,000 deaths.

It is difficult to determine the number of deaths caused by a benign tumor, although we can say with complete certainty that it is very low. Even when it develops in delicate areas like the brain, and as long as an early diagnosis is made, the survival rate is considerably high.

5. Classification

Just as there is no single type of tumor, there is no single type of cancer. In reality, it is a set of very diverse diseases that affect any organ.

Cancer is classified as a group of diseases. This is recognized by the WHO, and is classified as a group according to their characteristics and the part of the body they affect. Tumors are not officially considered a disease, but a condition or, in any case, an alteration of the tissues. It may seem like a minor difference, but from a medical point of view it is not.

6. Relapses

It is very unlikely that there will be a relapse when a benign tumor is removed. Cancer, especially those more aggressive varieties, has a high probability of returning in the future. This is known as cancer recurrence, and you can do it in the same place or in other parts of the body.

As you can see, there are solid criteria that allow us to distinguish between tumor and cancer. It is important that people know each of these, since you can assimilate a diagnosis with greater responsibility. During a diagnostic process, you can ask any questions to the specialist, so you can know the prognosis and severity.

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