Welcome to grouploop.org. A website about how to cope with being diagnosed with cancer.  This website is designed with teenage cancer patients in mind but our advice is equally valid for adults.On this website you can find guides that help you when:

We also feature a glossary that will teach you the most important cancer-related terms.

What is cancer?

Cancer is group of diseases that involves abnormal cell growth, where some of the body’s cells become abnormal and begins to divide too rapidly. Cancer can start almost anywhere in the human body, and many cancers can spread into surrounding tissue and/or travel to other parts of the body and form secondary cancers there.

Over a hundred different types of cancer have been diagnosed in humans. Previously, we used to sort cancer types based on where in the body they occurred or how the cancer cells looked in a microscope. Today, it is also common to characterize cancers based on the types of genetic alterations that are believed to be driving them. Researchers have found out that certain mutations commonly occur in many types of cancer, regardless of where in the body they first appear.

Do all cancers form solid tumours?

No, not all of them. Many types of cancer form solid tumours, which are masses of tissue. Some cancers, however, such as leukemia, are unlikely to form solid tumours.

Malign vs benign tumours

malign benign

Cancer tumors are malign tumours and can both invade nearby tissue and spread throughout the body, as opposed to benign tumours which neither invade nor spread. Benign tumours can become large and can be dangerous in their own way (especially in the brain), but they behave very different from malign tumours.

Malign tumours can invade nearby tissue, and it is also possible for cancer cells to break off and be transported to distant parts of the body where they become the starting point for new tumours. Both the blood system and the lymph system are known pathways for cancer cells.

When a benign tumours is removed, it will usually not grow back. Malignant tumours are much more likely to grow back after being removed.

Cancer cells

Less specialization

One important difference between cancer cells and normal cells is that cancer cells are less specialized. Normal cells grow to fullfil a specific job in the body, e.g. being red blood cells or being a type of skin cells. Cancer cells work differently and they also continue to divide in an uncontrolled fashion.

Ignores commands

In the human body, normal cells eventually receive signals that tell them to stop dividing or begin apoptosis – a process of regulated cell death. They receive the signals and act accordingly. Cancer cells on the other hand ignore these signals.

Can tweak the microenvironment to their own benefit

In order to sustain the rapid cell division, cancer cells need plenty of oxygen and nutrients. Some cancers cells influence the normal cells around them to obtain these resources. A cancer tumour can for instance induce the creation of dedicated blood vessels that cater to the tumour, providing it with ample amounts of oxygen and nutrients, and removing the large amounts of waste products generated by fast-growing cancers.

Can evade the immune system

One important task for the immune system is to remove damaged and abnormal cells from the body, before they can cause harm and disruptions. Some cancer cells are able to hide from the immune system and keep from being removed. One of the ways that they do this is to take advantage of certain special immune system cells whose job it is to prevent a runaway immune response.


Cancer cells appear when certain changes have happened to the genes that control the way our cells function – especially how they grow and divide.

In general, cancer cells feature more mutations than normal cells. It can sometimes be difficult to know what came first; are the mutations a driving force behind the cancer or have the mutations occurred as a result of the cancer. We do know that as the cancer continues to grow, additional changes do occur. Even within the same tumour, different cells can go through different genetic changes.


Research have found that cancer occurs both due to inherited factors and because of factors that the individual has been exposed to during their lifetime.

Examples of environmental factors that can cause damage to the DNA are radiation and certain chemicals in tobaccco smoke.

What are “the drivers of cancer”?

The genetic changes that contribute to cancer tend to impact three main types of genes:

  • Proto-oncogenes, which are genes involved in normal cell growth. Mutations in a proto-oncogene may cause it to turn into an oncogene, which in turn can promote the growth of cancer cells because the changes allow cells to grow and survive when they should not.
  • Tumor suppressor genes, which control cell growth and division.
  • DNA repair genes, which are involved in fixing damaged DNA.

Changes in these three gene types are known as the drivers of cancer.


Metastasis is the development of secondary malignant growths at a distance from a primary site of cancer. It occurs when cancer cells break away from their original spot and travel to another part of the body. Cancer cells are known to use both the blood system and lymph system as “highways” for traveling. They then start growing in another part of the body, where they form metastatic cancer.

When observed under a microscope, the metastatic cancer cells usually look the same as cancer cells from the original cancer site. Studies on the molecular level typically reveal common molecular features as well, such as the presence of specific chromosome changes in both the original cancer and the metastatic cancer.

Tissue changes that can develop into cancer

Some types of non-cancerous tissue changes in the body should be monitored because they are known to sometimes develop into cancer.

Here are some examples of such changes:

  • HyperplasiaThis is a condition where the cells within a certain tissue divide faster than the normal pace and extra cells build up. Hyperplasia can cause an organ to become extra-large. If we look at the tissue under a microscope, we see that the cells still look normal and that the tissue organization is the way it should be. Examples of common reason for hyperplasia are chronic inflammation, compensation for damage, and hormonal dysfunction.
  • DysplasiaIn dysplasia, there is a build up of extra cells, the cells look abnormal under a microscope and the tissue is not organized correctly. It is a much more serious condition than hyperplasia. Generally speaking, a high degree of abnormality in the cells are linked to a high risk of cancer eventually developing.For some types of dysplasia, monitoring isn’t enough – the condition should be treated. An abnormal mole forming on the skin might, for instance, be removed surgically instead of being left there to develop.
  • Carcinoma in situ is similar to cancer, but doesn’t fulfill the definition of cancer because the abnormal cells aren’t spreading to any other tissue. To prevent carcinoma in situ from developing into cancer, it is usually treated instead of just monitored.