Many of you have been getting Pap smears every year, and you might have heard that this is no longer necessary. This has caused confusion for many patients.
The Pap smear was developed in 1943 by Dr. Papanicolaou from my alma mater, Cornell University Medical College, as a means to detect cervical and endometrial cancer. The test has become the standard used worldwide to detect pre-cancerous cells, thus reducing the incidence of cervical cancer.
Recently, the American College of Obstetricians and Gynecologists issued new recommendations on the frequency of screening for cervical cancer as a result of recent medical advances.
Over the past few years, new research and development has thankfully identified the cause of most cervical cancers, Human Papillomavirus (HPV). The prevalence of HPV among those with cervical cancer is 99%.
There are many different strains of HPV. Some cause benign genital warts, some cause various degrees of abnormal cells on the cervix, and some cause cervical cancer.
HPV is the most common sexually transmitted infection, and it is estimated that 20 million people are currently infected with HPV, and 6.2 million new cases occur each year.
The good news is that most HPV infections clear spontaneously because the immune system fights them off. This typically happens within six months to two years. However, high-risk HPV strains that persist more than 2 years may cause abnormal cells. This is the single most important risk factor for cervical cancer.
In 2006, the FDA approved the marketing of Gardisil, a vaccine for the known high-risk strains of the virus. So far, Gardisil has been shown to reduce the incidence of persistent HPV infection and abnormal pap smears, known as dysplasia. It is currently approved for use in girls and young women aged nine to 26 (the population group it was tested on). It is delivered via a series of three injections over six months.
Keep in mind that the vaccine does not clear existing HPV infection, but rather protects against an initial infection. It does this by inducing antibodies (which attack infectious agents) in your body. Ideally, it should be received prior to the onset of sexual activity.
However, if you have already been infected with HPV, the vaccine can still be helpful since you probably were not infected by all four types of HPV that the vaccine protects against.
Previously, there was no specific testing for the HPV virus. Therefore, the Pap smear was the only test available to detect abnormal cells (and your risk for developing cervical cancer). You may be surprised to hear that the Pap smear is only just above 50% sensitive. That means that nearly half of the women who have abnormal cells on the cervix won’t find out from their Pap smears. This is why annual testing was needed.
The new test for high-risk HPV is significantly more sensitive in identifying your risk of developing clinically significant abnormal cells – and cervical cancer.
Therefore, your screening intervals can be spread out to every two to three years if you meet the following conditions:
- Normal Pap smear and HPV test.
- A healthy immune system.
- Normal Pap smears for at least three years.
- 30 to 64 years of age.
- I usually add the following condition: No new sexual partner in the past three years.
The American College of Obstetricians and Gynecologists suggests continuing annual screening for women aged 21 to 29.
Far too often, patients are not informed about why something is or isn’t necessary. When it comes to maintaining your health, being informed and understanding why you need or don’t need something is important. I hope this article helped clear up the question of why you might not need annual screening anymore.
Key points to remember:
- Cervical cancer is preventable and curable when detected early. The Pap smear can find abnormal cells before they cause cancer, and the HPV test can detect the high-risk strains of HPV that are linked to cervical cancer.
- Most women who test positive for the high-risk HPV will not be diagnosed with precancerous cells or cervical cancer.
- A negative HPV test and negative Pap smear is good assurance that your risk is very low and you can be screened less often.
- The more sexual partners you and your partner have had, the greater your risk of HPV exposure. Transmission can occur through genital contact regardless of whether intercourse has taken place, and condoms do not provide complete protection.