Screening and cancer


Updated April 2008 Cancer is primarily a disease of old age, and is the second most common cause of death after heart disease in most western countries. As life expectancy increases, so does the proportion of people who will eventually develop some form of cancer in later life. Cancer is not a single disease. Tumours arising in different tissues behave in different ways, and respond differently to treatment. All cancers have some elements in common such as their invasive growth. In recent years, improved techniques in the early diagnosis and treatment of cancer have led to more cures than ever before. Even if cancer cannot be cured, many treatments are available to relieve symptoms and improve quality of life.

Many types of cancer produce a solid tumour that forms in an organ, such as the breast, intestine, or bladder. If not detected and treated, these cancers may spread to other body tissues, specific examples of which, and some present screening programmes, are discussed below. Cancer can be detected before it causes symptoms, often during a routine screening test. Cancer is more often discovered when symptoms gradually develop and become noticeable over a period of weeks or months.

Symptoms of cancer may include:
  • a firm, often painless, lump in or beneath the skin
  • changes in the appearance of a mole
  • a nonhealing wound
  • blood in urine or sputum
  • changes in bowel habits
  • a discharge containing blood from bowel or vagina
  • persistent abdominal pain
  • hoarseness or changes in voice
  • difficulty in swallowing
  • severe, recurrent headaches
  • weight loss
  • unexplained tiredness
  • loss of appetite and nausea.
The three main techniques for treatment are broadly surgery, chemotherapy, and radiotherapy, with other treatments including biological and hormonal therapies. The chances of cancer being curable are highest if it is detected by screening at a sufficiently early stage. Depending on the type and stage of cancer, treatment may be intended to cure the cancer, slow the growth, or be palliative – in which treatment is intended to help a person live as comfortably as possible rather than attempt a cure.

In most cases, curative treatment involves the surgical removal of a tumour. Non-surgical treatment, such as chemotherapy and radiotherapy, are often given with the aim of destroying any cancer cells that have spread beyond the obvious solid tumour. Non-surgical treatments may also be used if a cure is not possible with the aim of slowing the growth of certain types of cancer rather than curing them. Palliative care can control the symptoms of cancer, maximising quality of life and provide psychological support.

Screening means looking for early signs of a particular disease in 'healthy' people who do not have any symptoms. Screening cannot prevent cancer; but it can help to find it as early as possible.[see reference 1] Information on cancer screening programmes on the NHS can be found here. The 2005 BMA Board of Science report Population screening and genetic testing provides an overview of the subject area; outlines current programmes in operation; and sets out useful sources for further information.

Breast cancer and screening
Although breast cancer can occur in men it most commonly affects women, and in particular those over the age of 50. The underlying cause of most breast cancers is unclear, although facts suggest that the female hormone oestrogen is an important factor. A tumour may first develop in the breast lobules (the structures that produce milk) and may eventually spread to other organs such as the lungs or the liver, before being detected.

Symptoms of breast cancer may often only affect one breast and may include:
  • a painless lump usually situated deep in the breast or just under the skin
  • dimpling or swelling of the skin in the area of the lump leading to an ‘orange peel’ appearance.
  • inversion of the nipple
  • bloodstained nipple discharge.
Breast screening is a method of detecting breast cancer at a very early stage. The NHS Breast Screening Programme provides free breast screening every three years for all women in the UK aged 50 and over. Women aged between 50 and 70 are currently routinely invited for breast screening every three years. Once women reach the upper age limit they are not sent routine invitations for breast screening but are encouraged to make their own appointments.[see reference 2]

There are over 90 breast screening units across the UK. Women are invited to a specialised screening unit, which can either be mobile, hospital based, or permanently based in another convenient location such as a shopping centre.[see reference 2] Some centres provide the results on the same day while others can take 48 hours or longer.[see reference 3] Women should still check their breasts for lumps, even if they are having mammograms every three years.

Cervical cancer and screening
Cancer of the cervix is one of the most common cancers affecting women in the UK, despite the fact that it can be effectively prevented by regular screening before symptoms appear. The cause of cancer of the cervix is not clear, but there is evidence that risk is increased by such factors as having unprotected sex from an early age, or with many partners. Cancer of the cervix does not always cause symptoms, but may, in some cases, cause abnormal vaginal bleeding, especially after sexual intercourse.

Later symptoms may include:
  • watery, bloodstained, offensive-smelling vaginal discharge
  • pelvic pain
  • pain during intercourse.
Cervical screening is a method of preventing cancer by detecting and treating abnormalities which could lead to cancer in a woman's cervix. The first stage in cervical screening is a smear test. All women between the ages of 25 and 64 are eligible for a free cervical smear test. Women should receive their first invitation at 25 years and then follow up screenings every three or five years depending on age.[see reference 4]

The screening programme stops at 64 because women who have had normal smears are very unlikely to go on to develop cervical cancer after this age. Women may be screened over 65 if they have not been screened since age 50 or have had recent abnormal tests.[see reference 4]

Bowel cancer and screening
Colorectal (bowel) cancer is a malignant (cancerous) growth that starts on the inside wall of the bowel. It can grow there for a relatively long time before spreading to other parts of the body. Colorectal cancer is rare under 40 and most often occurs in people over 60. Bowel cancer can develop in any part of the large bowel, including the colon and rectum.[see reference 5]

There are two main methods of screening for bowel cancer: Some people are offered regular screening if they are thought to be at higher than average risk of bowel cancer. The NHS Bowel Cancer Screening Programme is gradually being rolled out nationally. with complete covereage intended by 2009.. The programme involves using a self administered testing kit to obtain a sample which is then sent to the lab. The kits will offer screening to all men and women aged 60 to 69. Those over 70 can request a screening kit using a freephone number.

Prostate cancer and screening
Prostate cancer is the most commonly diagnosed male cancer in the UK, with older people being most at risk. The exact cause of prostate cancer is not known, although the male sex hormone testosterone, produced by the testes, has been found to influence the growth and spread of the tumour. Many tumours, however, grow slowly, especially in older men, and may never cause symptoms.

If symptoms do occur they may include:
  • weak urinary stream or inability to pass urine normally
  • frequent urge to pass urine, especially during the night
  • rarely, blood in the urine.
Initial symptoms can be due to the spreading of the cancer to other parts of the body, most commonly the bones, lymph nodes, and lungs, with symptoms including:
  • back pain
  • enlarged lymph nodes
  • shortness of breath
  • significant weight loss.
A diagnosis of cancer of the prostate gland does not necessarily mean that the cancer will cause symptoms or be life threatening. Sometimes, the best policy, especially in older men, is to defer treatment and begin regular check-ups to monitor the disease. Surgery may result in impotence and urinary incontinence.

In response to growing public concern about the risks of prostate cancer the government has launched a Prostate Cancer Risk Management Programme. One of the main aims of the programme is to ensure that men who are concerned about the risk of prostate cancer receive clear and balanced information about the advantages and disadvantages of the Prostate Specific Antigen (PSA) test and treatment for prostate cancer.[see reference 6]

The National Screening Committee's policy on prostate cancer screening is that it can be provided on request, provided that the man fully understands the testing risks and benefits. The Committee recommended to Ministers of the four Health Departments that prostate screening should not be introduced and men should not be invited for a PSA test in the same way as in other screening programmes. It was considered that there was no good evidence of benefit using the Committee's criteria.[see reference 7]

Ovarian cancer and screening
Cancer of the ovary is a cancerous tumour that can develop in one or both ovaries and is often associated with a high death rate – usually explained by the fact that symptoms do not develop until later in the progress of the disease, which delays the diagnosis and treatment. The cause of cancer of the ovary is not known, although women who have never had children, or have had a later menopause are more likely to develop cancer of the ovary. A complete recovery from cancer of the ovary is possible only if the condition is diagnosed and treated while in the early stages. In all other cases, chemotherapy can prevent further spread of the cancer, sometimes for years, but can rarely eliminate the cancer altogether.

Symptoms are rare in the early stages, although they may be similar to those of an ovarian cyst, such as irregular periods. In most cases, symptoms occur only if the cancer has spread to other organs.

They may include:
  • pain in the lower abdomen
  • swelling in the abdomen caused by excess fluid
  • frequent need to pass urine
  • rarely, abnormal vaginal bleeding
  • weight loss
  • nausea
  • vomiting.
At the moment, there is no screening test that is reliable enough to use for ovarian cancer in the general population. But there are ongoing clinical trials to look into screening for the following groups:
  • women at high risk of cancer of the ovary
  • women in general.
Until these trials publish their findings, the effectiveness of the screening tests remains uncertain.[see reference 8]

References:
  1. Cancer Research UK - Screening for cancer (Accessed April 2008)
  2. NHS Cancer Screening Programmes - NHS Breast Screening Programme - www.cancerscreening.nhs.uk/breastscreen (Accessed April 2008)
  3. Cancer Research UK - Breast cancer tests (Accessed April 2008)
  4. NHS Cancer Screening Programmes - NHS Cervical Screening Programme - www.cancerscreening.nhs.uk/cervical (Accessed April 2008)
  5. Cancer Research UK - Bowel cancer at a glance (Accessed April 2008)
  6. NHS Cancer Screening Programmes - Aim of Prostate Cancer Risk Management - www.cancerscreening.nhs.uk/prostate (Accessed April 2008)
  7. National Screening Committee Policy - prostate cancer screening - www.library.nhs.uk/screening (Accessed April 2008)
  8. Cancer Research UK - Ovarian cancer screening - www.cancerhelp.org.uk (Accessed April 2008)
Further information:

© British Medical Association 2008

Log in to your BMA here