Sixty to eighty percent of the women who get cervical cancer have never had a Pap smear or have not had one in last 5 years. The Papanicolaou test is an affordable and dependable screening test for cervical cancer that has been widely available since the 1950's. Despite this, many women still lack access to cervical cancer screening. Cervical cancer disproportionately affects low income women of color. For instance, Latinas are at highest risk in California (their death rate is 40% higher than other women). African Americans are diagnosed at a later stage and it is the most common cancer among Vietnamese women (vs. breast cancer). Approximately 11,270 cases of cervical cancer were diagnosed in 2009 in the US. Approximately 4,000 women die from cervical cancer each year (ACS, 2011).
Almost 100% (99.9%) of cervical cancers are caused by a sexually transmitted virus called human papilloma virus (HPV). It is a group of double stranded DNA viruses encased in a protein capsid. There are about 120 different types; about 40 infect the genital tract. They are categorized in to low risk types like those that cause genital warts and the high risk types that cause cervical cancer. HPV is the most common sexually transmitted infection. The lifetime risk of getting it is 75-90%. So, if you are sexually active, you will likely be exposed to it.
When should Pap smear screening begin? Some organizations say age 21 (*ACOG, 2009) and others say 3 years after the onset of vaginal intercourse or no later than 21yrs old (**ACS, 2002). It is probably best not to begin Paps until age 21, regardless of first intercourse (ACOG Committee on Adolescent Health Care, 2010).
*ACOG: American Congress of Obstetricians and Gynecologists. See their guidelines.
**ACS: American Cancer Society. See the ACS guidelines.
There are a number of reasons for waiting to start Pap smear screening. First, most HPV infections are transient, we get exposed to it and then our body gets rid of it. Second, HPV infection persist for more than 10 years before becoming cancer. Fortunately, spontaneous regression is common even after the cells have become abnormal or dysplastic. In young women, even high grade dysplasia can go away on its own. So it is best to monitor it rather than treat it to avoid the risk of damaging the cervix. When I started caring for women with abnormal Pap smears about 20 years ago we thought that all types of cell changes called dysplasia were "precancerous". Now we know that this is not true and we can avoid putting women through unnecessary diagnostic tests and treatment procedures.
Do we need to have Pap smears the rest of our lives? No! You can stop at age 65 (ACOG) or 70 (ACS). IF you have had 3 consecutive normal Pap smears in the prior 10 years or if you have had a hysterectomy for benign disease (ACOG, ACS).
How often should women get Pap smears? Women less than age 30 should have them every 2 years (ACOG, 2009). Women over age 30 should have them every 3 years after 3 normal Paps (ACOG) or every 2-3 yrs (ACS). Some providers screen for high risk types of HPV along with Pap smears. HPV screening should only be done in women over age 30 and then screening should only occur every 3 years. Doing Pap smears more often can lead to false positive tests. This leads to women getting unnecessary biopsies and treatments. The combination of tests is thought to be more sensitive than a Pap smear alone. Exceptions: women who have had high grade dysplasia, were exposed to DES or who are immune compromised should have Pap smear screening every year.
If a young woman gets the HPV vaccine can she avoid getting Pap smears? Unfortunately the answer is no, she still needs to get Pap smears. The HPV vaccines do not protect against all types of HPV that cause cancer. There are two vaccines available now. Gardasil was approved by the FDA in 2006 and it protects against HPV types 6, 11, 16, 18. These HPV types are responsible for 70% of the cervical cancers and 90% of genital warts. Cervarix was approved in 2009 and it protects against HPV 16 & 18, just 2 of the types that commonly cause cancer. The HPV vaccine works best when it is given to young women and men before they become sexually active. (For more information on the HPV vaccine, see the May 2007 WHH newsletter.) It is very exciting that we have a vaccine that protects against cancer; it is the first of its kind!
Is it is time for your Pap smear? If so, I would be happy to see you at the UCSF Osher Center for Integrative Medicine. We are in our lovely new building at the corner of Divisadero and Post. 415-353-7700.
