Cervical cancer - incidence, mortality and risk factors

• What is the incidence of cervical cancer?
• How many women die from cervical cancer?
• What are the risk factors for cervical cancer?
• Is cervical screening effective?
• Coverage of the target population

What is the incidence of cervical cancer?

In 2000, there were 2,424 new registrations of invasive cervical cancer in England.¹

Cervical cancer incidence fell by 42 per cent between 1988 and 1997 (England and Wales). This fall is directly related to the cervical screening programme².

There was a 25 per cent decrease in the incidence rate of cervical cancer for women under the age of 70 from 1990 to 1992. This has been attributed to a rapid increase in coverage of the cervical screening programme which occurred from 1989 onwards³.

In 1995, there were 10.4 newly diagnosed cases of cervical cancer per 100,000 women⁴. By 1999, this had fallen to 9.3 per 100,000 women⁵.

Cervical screening now saves approximately 4,500 lives per year in England.⁶ Cervical screening prevents up to 3,900 cases of cervical cancer per year in the UK.⁷

21,617 women in England were found to have the most severe type of CIN (CIN 3)⁵.

UK incidence rates are slightly below the European Union average while the mortality rates are slightly above.⁸

An estimated 471,000 new cases of cervical cancer are diagnosed each year in the world with 80 per cent of these occurring in the less developed world.⁸

¹National Statistics, Cancer registrations in England, 2000
²National Statistics, Health Quarterly Statistics 07, Autumn 2000
³Cancer Incidence and Mortality in England and Wales: trends and risk factors. Swerdlow, Silva and Doll OUP 2001
⁴National Statistics MB1 No 28 Cancer statistics Registrations 1995-1997
⁵National Statistics MB1 No 30 Registrations of cancer diagnosed in 1999
⁶Julian Peto et al, The Lancet (Vol.364: 249-56)
⁷Sasieni, British Journal of Cancer 1996 Apr; 73(8):1001-5
⁸Cancer Stats, Cervical Cancer - UK, January 2003, Cancer Research UK, London

How many women die from cervical cancer?

For the first time ever death rates from cervical cancer have fallen below 1,000 in England. In 2002, 927 deaths from cervical cancer were registered.¹

Mortality rates generally increase with age with the highest number of deaths occurring in the 75-79 age group. Less than 5 per cent of cervical cancer deaths occur in women under 35.²

Mortality rates in 2000 were 60 per cent lower (3.3 per 100,000 women) than they were 30 years earlier (8.3 per 100,000 in 1971).²

Cervical cancer is the eleventh most common cause of cancer deaths in women in UK, accounting for around 2 per cent of all female cancers.²

The latest relative survival figures for England show that an average of 84 per cent of women diagnosed with cervical cancer between 1993 and 1995 were alive one year later and 66 per cent were alive five years later.²

¹Health Statistics Quarterly, Summer 2003, National Statistics
²Cancer Stats, UK, January 2003, Cancer Research UK, London

What are the risk factors for cervical cancer?

The exact cause of cervical cancer is not known. However, it is known that:

• certain types of Human Papilloma Virus (HPV) are linked with around 95% of all cases of cervical cancer
• women with many sexual partners, or whose partners have had many partners, are more at risk
• using a condom gives some protection while long term use of oral contraceptives increases the risk
• the benefits of taking oral contraceptives far outweigh the risks for the majority of women
• women who smoke are about twice as likely to develop cervical cancer as non-smokers
• women with a late first pregnancy have a lower risk than those with an early pregnancy; the risk rises with the number of pregnancies
• women in manual social classes are at higher risk than those in non-manual social classes
• women who have had a total hysterectomy for other, non-malignant, reasons cannot get cervical cancer and no longer need cervical screening
• Women who take immunosuppressant drugs (for example, after an organ transplant) are at increased risk of developing cervical cancer

Despite the risk factors, cervical screening can prevent around 75% of cancer cases in women who attend regularly. Screening is one of the best defences against cervical cancer. Many of those who develop it have never been screened. The biggest risk factor therefore is non-attendance.

Is cervical screening effective?

Whilst cervical screening cannot be 100% effective, cervical screening programmes have been shown to reduce the incidence of cancer in a population of women. For example:

Coverage of the target population

The effectiveness of the programme can also be judged by coverage. This is the percentage of women in the target age group (25 to 64) who have been screened in the last five years. If overall coverage of 80% can be achieved, the evidence suggests that a reduction in death rates of around 95% is possible in the long term. In 2001/2 the coverage of eligible women was 81.6 per cent.¹

From 2001/2, women who have only had an inadequate smear are no longer counted as screened in the coverage calculations. Coverage is now calculated at 3.5 and five years rather than at 3 and 5 years.

¹Department of Health Statistical Bulletin, Cervical Screening Programme, England: 2001-2002