Tuesday 24 January 2012

Cervical cancer

Definition of cervical cancer: Cancer that forms in tissues of the cervix (the organ connecting the uterus and vagina). It is usually a slow-growing cancer that may not have symptoms but can be found with regular Pap tests (a procedure in which cells are scraped from the cervix and looked at under a microscope). Cervical cancer is almost always caused by human papillomavirus (HPV) infection.  Estimated new cases and deaths from cervical (uterine cervix) cancer in the United States in 2011:

New cases: 12,710
Deaths: 4,290

SEER Incidence

From 2004-2008, the median age at diagnosis for cancer of the cervix uteri was 48 years of age. Approximately 0.2% were diagnosed under age 20; 14.3% between 20 and 34; 25.8% between 35 and 44; 23.9% between 45 and 54; 16.4% between 55 and 64; 10.6% between 65 and 74; 6.4% between 75 and 84; and 2.5% 85+ years of age.
The age-adjusted incidence rate was 8.1 per 100,000 women per year. These rates are based on cases diagnosed in 2004-2008 from 17 SEER geographic areas.

Survival & stage

Survival can be calculated by different methods for different purposes. The survival statistics presented here are based on relative survival, which measures the survival of the cancer patients in comparison to the general population to estimate the effect of cancer. The overall 5-year relative survival for 2001-2007 from 17 SEER geographic areas was 68.6%. Five-year relative survival by race was: 70.0% for white women; 58.4% for black women.

Stage at Diagnosis Stage
Distribution (%)
5-year
Relative Survival (%)
Localized (confined to primary site) 48 90.9
Regional (spread to regional lymphnodes) 36 56.9
Distant (cancer has metastasized) 12 16.5
Unknown (unstaged) 4 53.7


The stage distribution is based on Summary Stage 2000.

Lifetime Risk

Based on rates from 2006-2008, 0.68% of women born today will be diagnosed with cancer of the cervix uteri at some time during their lifetime. This number can also be expressed as 1 in 147 women will be diagnosed with cancer of the cervix uteri during their lifetime. These statistics are called the lifetime risk of developing cancer. Sometimes it is more useful to look at the probability of developing cancer of the cervix uteri between two age groups. For example, 0.25% of women will develop cancer of the cervix uteri between their 50th and 70th birthdays.

Prevalence

On January 1, 2008, in the United States there were approximately 243,884 women alive who had a history of cancer of the cervix uteri. This includes any person alive on January 1, 2008 who had been diagnosed with cancer of the cervix uteri at any point prior to January 1, 2008 and includes persons with active disease and those who are cured of their disease. Prevalence can also be expressed as a percentage and it can also be calculated for a specific amount of time prior to January 1, 2008 such as diagnosed within 5 years of January 1, 2008.

Screening

The Pap test (sometimes called a Pap smear or cervical cytology) is a way to examine cells collected from the cervix (the lower, narrow end of the uterus). The main purpose of the Pap test is to detect cancer or abnormal cells that may lead to cancer. It can also find noncancerous conditions, such as infection and inflammation.


A Pap test can be done in a doctor’s office, a clinic, or a hospital. While a woman lies on an exam table, the clinician inserts a speculum into her vagina to widen it. A sample of cells is taken from the cervix with a wooden scraper and/or a small cervical brush. The cells are then prepared for analysis in either of two ways. In a conventional Pap test, the specimen (or smear) is placed on a glass microscope slide and a fixative is added. The slide is then sent to a laboratory for examination. In an automated, liquid-based cytology Pap test, cervical cells collected with a brush or other instrument are placed in a vial of liquid preservative. The vial is sent to a laboratory, where an automated device prepares a thin layer of cells on a slide for analysis under a microscope.
In the United States, automated liquid-based cytology has largely replaced conventional Pap tests. One advantage is that samples can also be tested for the presence of human papillomavirus (HPV), certain types of which cause most cervical cancers. Liquid-based cytology also appears to reduce the likelihood of an unsatisfactory specimen. However, both methods appear to have a similar ability to detect cellular abnormalities.

A woman should have this test when she is not menstruating; the best time is between 10 and 20 days after the first day of her last menstrual period. For about 2 days before a Pap test, she should avoid douching or using vaginal medicines or spermicidal foams, creams, or jellies (except as directed by a doctor) because they may wash away or hide abnormal cells. After the test, she can go back to her normal activities and return to work right away.



HPV testing alone is not useful for cervical cancer screening of women under 30 years of age because the rate of false-positive tests would be unacceptably high. That is, many women would be found to be infected with high-risk HPV, but in most of them the infection would clear on its own. However, the Food and Drug Administration has approved testing for DNA from high-risk HPV types in conjunction with Pap smears for routine cervical screening of women aged 30 years and older. A negative HPV DNA test increases assurance that there is very little risk of a serious abnormality developing over the next several years.


References

Howlader N, Noone AM, Krapcho M, Neyman N, Aminou R, Waldron W, Altekruse SF, Kosary CL, Ruhl J, Tatalovich Z, Cho H, Mariotto A, Eisner MP, Lewis DR, Chen HS, Feuer EJ, Cronin KA, Edwards BK (eds). SEER Cancer Statistics Review, 1975-2008, National Cancer Institute. Bethesda, MD, http://seer.cancer.gov/csr/1975_2008/, based on November 2010 SEER data submission, posted to the SEER web site, 2011.

http://www.cancer.gov/ 





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