Rare, slow growing type of brain tumor. Develops from blood vessel cells in the brain. Almost always benign.


Swelling where blood has collected under the skin.

Haematopoietic Tissue

The tissue where the blood cells are made. The bone marrow in adults.


Found in red blood cells. Iron containing pigment which carries oxygen around the body. See Red Blood Cells.

Hair Follicle
(Hair Follicles)

The sac in which the hair grows in the scalp. The hair follicles are damaged by some chemotherapy drugs. This is why chemotherapy often causes hair loss.

Head And Neck Cancer
(Head And Neck)

Term used by doctors to mean cancer affecting the lip, mouth, nose etc. Does not usually mean cancers of the oesophagus (gullet) or larynx (voice box).

Helper T Cells

Type of white blood cell. Helper T cells stimulate B cells to make antibodies as part of the immune response. See Antibodies, B Cells, Immune System, T cells.

Hemibody Irradiation

Radiotherapy treatment of half the body at a time. Usually used to treat secondary bone cancer.


Drug which stops the blood from clotting. Sometimes said it "thins the blood".

Hepatic Artery

The main blood vessel carrying blood to the liver.

Hepatic Artery Infusional Chemotherapy
(Hepatic Artery Pump)

Chemotherapy that is given straight into the main blood vessel to the liver. Used to treat secondary bowel cancer in the liver.

Hepatitis A
(Hepatitis A Vaccine)

Infectious disease. You can have a vaccination against hepatitis A if you are having chemotherapy. See Vaccination.

Hepatitis B
(Hepatitis B Vaccine)

Infectious disease. You can have a vaccination against hepatitis B if you are having chemotherapy.


The passing on of characteristics to the next generation. These can be physical or mental characteristics or the tendency to develop particular illnesses. We inherit these characteristics from our parents through our genes and chromosomes. The chromosomes are made up of genes. We inherit half our chromosomes (and so half our genes) from our mother and half from our father. See Chromosome, Gene, Genetic Predisposition.

Hickman Line

Type of central line that is put into the chest under anaesthetic. See Central Line.

High Dose Chemotherapy

Anti-cancer drug treatment using very high drug doses. Needs to be followed by a transfusion of bone marrow or stem cells. See Bone Marrow Transplant, Chemotherapy, Stem Cell Transplant.

High Factor Sun Cream

A sun cream which provides maximum protection against ultra violet light. Usually factor 20-25. It is important that anyone who has had skin cancer, or who has had radiotherapy should use a high factor sun cream. They should also stay out of the sun as much as possible. Some chemotherapy drugs can also cause skin reactions in the sun. See Chemotherapy Drugs, Radiotherapy.

High Grade

See Grade. Means the cells look less like normal cells and so the cancer may be more malignant.

High Grade: Lymphomas
(High Grade Non-Hodgkin's Lymphoma)

High grade lymphomas are faster growing and more acute diseases than low grade. They are usually treated with more intensive chemotherapy treatment than low grade, but if treated at an early stage, may just be treated with radiotherapy. See Chemotherapy, Grade: Lymphomas, Radiotherapy.

High Grade: Solid Tumors

Means the cells are closer to looking like normal cells and so the cancer may not be as malignant. See Grade: Solid Tumors.

Hoarse Voice

The voice sounds husky and croaking. Can be a symptom of lung cancer. Caused because a tumor is pressing on a nerve that supplies the voice box.

Hodgkin's Disease

A cancer of the lymphatic system. It is a type of lymphoma. There are two main types of lymphoma: Hodgkin's disease and Non Hodgkin's lymphoma. Hodgkin's Disease is often very successfully treated, even when it has spread from where it started. See Lymphatic System, Non Hodgkin's Lymphoma.

Hormone Dependent
(Hormone Sensitive)

A hormone dependent cancer is one that is stimulated to grow by the presence of a particular hormone. Breast cancer and prostate cancer are both hormone dependent cancers. See Hormones.

Hormone Replacement Therapy
(Hormone Replacement Therapies HRT)

Treatment with female sex hormones (either estrogen alone, or more usually, estrogen and progesterone) after natural or early Menopause. Helps prevent symptoms such as Hot Flashes and long term problems such as bone thinning.

Hormone Therapy
(Hormone Treatment)

Treating a disease with hormones, or by blocking the action of hormones. See Hormones.


Natural chemicals made in one part of the body which travel in the bloodstream and make things happen in another part of the body. Some cancers are stimulated to grow by hormones, particularly the sex hormones (testosterone in men and estrogen in women).

Hot Flashes

Side effect of some hormone treatments. Sudden feeling of being very hot. May go red in the face and sweat. Lasts for a few minutes only, but can happen quite often in some people, particularly at night. Similar to effects noticed by women going through the menopause or 'change of life'.

Hot Spots

Area which shows up on a bone scan. Means there is damage to bone. This could be arthritis, an old fracture or cancer in the bones. See Bone Scan.


Too much calcium in the blood. Causes drowsiness and sickness at first and unconsciousness if untreated. Often caused by cancer affecting the bones.

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