What is cancer?

Our bodies are made up of millions of cells. They are always replacing old cells with new ones to keep us healthy and to heal areas if we get hurt, for example if we get a cut or a graze.  

When our body destroys an old cell, one of the remaining cells will make a copy of itself by dividing into two, replacing the old cell. This process is usually very controlled so that the number of new cells our body makes is the same as the number that were old and destroyed. But sometimes too many new cells are made. The cells can’t respond to signals telling them to stop dividing. When this happens, a group of new cells form a lump called a tumour.

Tumours

A tumour is any abnormal mass of tissue (a collection of cells). Tumours are also sometimes called neoplasms. Like a cyst, a tumour can form in any part of the body.  

A tumour can be:  

• benign, which means they are non-cancerous  
• malignant, which means they are cancerous  
• borderline which is not cancer but contains malignant cells. It is between malignant and benign.

To find out whether a tumour is benign or malignant, your medical team may need to remove it with surgery. Once it’s been removed it can be examined by a pathologist. This is a specialist doctor who looks at the tissue under a microscope to make a diagnosis.

Benign tumours:

Benign tumours are made up of non-cancerous cells. They grow slowly and don’t spread to other parts of the body, but they may cause symptoms. In most cases they don't come back after having surgery to remove them.

Borderline tumours:  

Compared to cancerous tumours, borderline tumours are rarer and usually grow more slowly. They are often treated with surgery alone. In borderline tumours, the cells look different to healthy cells (abnormal), but they are not considered cancerous. Rarely, they can spread to other parts of the body.

Cancer Research UK has more information on borderline ovarian tumours.

Malignant tumours:

Malignant tumours are made up of cells that grow out of control. These tumours are considered cancerous. Cells in these tumours can spread into nearby tissues and other parts of the body.  

The area of the body where a tumour first develops is known as the primary cancer site. Cells can move away from the original tumour area and spread elsewhere in the body. The stage of the cancer describes if and how far the cancer has spread.  

Cancer cells can spread to other parts of the body through:

• the bloodstream
• the peritoneal fluid. The peritoneum is a large, thin, flexible sheet of tissue that covers the organs inside your abdomen (tummy) including your bowel, stomach, liver and reproductive organs. It makes a fluid that covers your organs making them slick, in part to stop them from sticking together. This fluid is called the peritoneal fluid.
• the lymphatic system. The lymphatic system is part of your immune system. It’s made up of tiny vessels similar to blood vessels which move a fluid called lymph throughout your body.  

If cancer cells reach other parts of the body, they can continue to grow and form a new tumour at that site. This is known as metastatic or secondary cancer. Secondary cancers keep the name of the original tumour location. So if ovarian cancer spreads to the liver, it is still called ovarian cancer and it is different from a cancer that starts in the liver.  

Ovarian cancer

Ovarian cancer starts from the cells in and around the ovary. There are many different types of ovarian tumours. The different types of ovarian cancer are named after the types of cells that they come from.

What are ovaries?

The ovaries are two small organs, each about the size and shape of an almond. They’re located low in the tummy area called the pelvis, just behind the pubic area.

They form part of the female reproductive and hormonal systems and store a supply of eggs. The menstrual cycle is the time from the first day of a period to the day before the next period. It is a monthly cycle that happens until the menopause.

During the menstrual cycle, an egg is released from one of the ovaries. This is called ovulation. The egg goes through the fallopian tubes and into the womb, ready for fertilisation (when sperm and an egg join together). If the egg is fertilised and implants in the womb, a baby develops. After menopause, your ovaries stop releasing eggs and the menstrual cycle stops. The ovaries also make the female hormones oestrogen and progesterone.

If you’re diagnosed with ovarian cancer, you will have tests to find out:

• the type of ovarian cancer - this is based on what type of cells the cancer started from. It is also called the histological type
• the stage, which describes if and how the cancer has spread
• the grade, which means how different the cancer cells look compared to normal cells.  

Understanding the type, stage and grade of cancer can help you when speaking to your specialist treatment team about your diagnosis and treatment options. 

Primary peritoneal and fallopian tube cancer

The fallopian tubes, ovaries and peritoneum are all close to each other in the pelvic (lower tummy) area.

The peritoneum is a large, thin, flexible sheet of tissue that covers the organs inside your abdomen (tummy) including your bowel, stomach, liver and reproductive organs. If the cancer starts in the peritoneum, it is called primary peritoneal cancer (PPC). 

The fallopian tubes link your ovaries and womb (uterus). If the cancer starts in the fallopian tubes, it is called fallopian tube cancer.

Fallopian tube cancer and primary peritoneal cancer are treated in the same way as ovarian cancer because they behave in the same way and respond to the same treatments.  

Metastatic ovarian cancer

Ovarian cancer metastases (secondary cancers) are tumours that grow in other parts of the body because of the spread of ovarian cancer cells. When ovarian cancer cells spread, they tend to form tumours on:

• the lining of the tummy (abdomen) which is called the peritoneum.
• the omentum. This is a fatty layer of tissue that hangs downwards from the stomach
• the surface of the liver.

Sometimes they can form lumps inside of the liver, the spleen or the lungs but this is less common.

These lumps often create extra fluid in the tummy. This fluid can build up in the tummy area (abdominal cavity). This buildup of fluid in the tummy area is called ascites. It can cause uncomfortable symptoms such as:  

• indigestion
• bloating (abdominal swelling)
• shortness of breath
• loss of appetite
• constipation  
• needing to wee (pass urine) more often
• feeling sick (nausea) or being sick (vomiting).  

More support and information

• If you have any questions or would like to discuss this information with an expert, give our specialist nurse-led support line a call at 0808 802 6000
• Macmillan and Cancer Research UK have more information about ovarian cancer