haematology [hae-ma-tol-o-gy] The branch of medicine that studies the blood . A doctor specialising in diseases of the blood is called a haematologist.

haematoma An accumulation of blood in the tissues that clots to form a solid swelling.

haematuria [hae-ma tu-ri-a] Blood in the urine.

hepatoblastoma [he-pat-o bla-sto-ma] A type of liver cancer that occurs in children, often confined to one lobe of the liver . In such cases, it may be surgically removed.

histology [his-tol-o-gy] The study of body cells and of the structure of body tissues, using a microscope.

HIV see AIDS .

Hodgkin's disease see lymphoma .

hormone (adj. hormonal) A substance which has a specific effect on the way the body works. Made in very small amounts by a gland , various hormones help to regulate and coordinate growth, metabolism and reproduction. They are distributed in the bloodstream.

hormone receptors Indicators on the surface of some cancer cells that suggest the cancer depends on hormones to help it grow, and it may thus respond to hormone therapy : seeoestrogen receptor test , progesterone receptor test .

hormone replacement therapy (HRT) Female hormones (oestrogen and progesterone) given to women after the menopause (change of life) to replace the hormones no longer produced by the ovaries. HRT is often prescribed after ovarian cancer surgery.

hospice care, palliative care Care that provides for all the medical and nursing needs of the patient for whom cure is not possible, and for all the psychological, social and spiritual needs of the patient and family, for the duration of the patient's illness, and includes bereavement care.

host The person receiving a transplanted tissue or organ .

hot spot Injected radioisotopes travel via the bloodstream to a cancer in the body where they show up as radioactive spots (hot spots) during bone scans : see nuclear medicine .

human immunodeficiency virus (HIV) [hu-man im-mu-no de-fic-ien-cy vi-rus, H-I-V] see AIDS .

hypercalcaemia The presence of an abnormally high level of calcium in the blood, usually due to the breakdown of bone. This can cause nausea, pain, thirst and confusion.

hypernephroma [hy-per neph-ro-ma] see renal cell carcinoma .

hyperplasia [hy-per pla-si-a] The increased growth or production of normal cells in part of the body. This may occur normally in some conditions, such as when the breasts enlarge during pregnancy. However when it occurs in the lining of the uterus (endometrial hyperplasia), it may develop into cancer of the uterus (uterine cancer ).

hyperthermia [hy-per ther-mi-a] 1. Greatly increased body temperature. 2. The use of heat to kill cancer cells. It is sometimes used to enhance the effect of radiotherapy . Many doctors feel hyperthermia has not been proved to be an effective treatment.

hysterectomy [hys-ter ec-to-my] The surgical removal of the uterus and the cervix