Cervical Cancer Awareness Month: Prevention & Screening
Cervical Cancer Basics
January is Cervical Cancer Awareness Month in the United States. Cervical cancer is cancer of the cells lining the cervix, the lower part of the uterus. The cervix connects the body of the uterus with the vagina. Cancer begins in the cervix when cells begin to grow out of control. The most common cause of cervical cancer is human papillomavirus (HPV) infection.
In 2022, it is estimated that about 14,100 new cervical cancer cases were diagnosed in the United States. About 4,280 people died from cervical cancer. In Minnesota, women of color are especially at risk for developing and dying from cervical cancer. Incidence rates of cervical cancer are highest for American Indians in Minnesota, and mortality rates are highest for Asian women. However, cervical cancer rates are declining in Minnesota and the United states due to screening and prevention methods.
The cervix is made up of two parts and two different types of cells. The endocervix is the opening that leads to the uterus, and it is covered by glandular cells. The exocervix is the outer part of the cervix and is covered in squamous cells. The area that these two types of cells meet is called the transformation zone. Most cervical cancers begin in the transformation zone.
Cancer in the transformation zone of the cervix typically occurs gradually. Normal cells develop abnormal changes that are considered “precancerous.” For some, precancerous cells will resolve without treatment. For others, precancerous cells will develop into cervical cancer.
Cervical Cancer Screening
These changes must be detected through cervical cancer screening. Cervical cancer screening includes the Pap test, also referred to as a Pap smear, and HPV test. These tests can catch cervical cancer early or before precancerous changes develop into cancer, leading to earlier treatment and better outcomes for patients.
The Pap test is a procedure that collects cells from both the exocervix and endocervix. The cells are placed on a glass slide or in a bottle with liquid to preserve the cells. The cells are then sent to a lab to be examined under a microscope to check for precancerous changes and cervical cancer. The Pap test was the first-ever cancer screening test to be developed and widely used.
In the early 1900s, cervical cancer was one the leading causes of death in women in the United States, with more than 40,000 deaths each year. The first cervical cancer screening test was developed by Greek scientist Georgios Papanicolaou over two decades. The test swabbed the cervix and examined cells under a microscope. In 1939, Papanicolaou and his study team tested the cervical cancer screening test on more than 3,000 women. The researchers diagnosed 127 cases of cervical cancer. Nearly all the cervical cancer cases were invisible to the eye and visual inspection of the cervix and would not have been discovered without looking at cells under a microscope.
The Pap test was further perfected by Dr. J Ernest Ayre, a Canadian gynecologist. With Papanicolaou’s initial test, cells from the vagina and cervix were collected with a glass pipette, which only allowed a small number of cells to be obtained. Ayre altered the test and used a scraping method with a spatula, allowing more cells to be easily collected. The Ayre Spatula was patented in 1949.
Cervical cancer screening clinical trials and programs were slowly launched through the 1950s and 1960s until they became a regular part of women’s annual health care. In the 1990s, new liquid-based cytology methods were used to develop an additional Pap test method in which cells are suspended in a liquid and preserved for testing instead of being smeared on a slide. This method may be more reliable and efficient, and both methods have similar efficacy in detecting cervical cancer.
The Pap test is now considered the most successful cancer screening test. As a result of the Pap test, cervical cancer deaths have decreased by more than 70 percent in the United States. With these positive steps forward, experts adjusted cervical cancer screening guidelines in 2012. Prior to this, cervical cancer was usually recommended annually for all women. The latest guidelines state:
- Women under age 21 should not receive cervical cancer screening
- Women aged 21 to 29 should receive a Pap test every three years
- Women aged 30 to 65 should receive a Pap test AND HPV testing (cotesting) every five years, OR a Pap test alone every three years and HPV test alone every five years
- Women over age 65 should not receive cervical cancer screening after adequate negative prior screening results
Cervical Cancer Prevention
Cervical cancer can be prevented with screening. Screening can detect cervical changes before cancer develops, or at earlier cancer stages. Cervical cancer can also be prevented with vaccination. 90 percent of cervical cancers are caused by human papillomavirus (HPV). HPV is a group of more than 150 viruses. HPV can cause six different cancers by developing cell abnormalities, including oral cancers, reproductive cancers, and, most frequently, cervical cancer. It is estimated that HPV causes 36,000 cancer cases per year in men and women. HPV vaccination would prevent 32,000 of those cancer cases from ever developing.
The HPV vaccine is a significant milestone for cancer research and illustrates the importance of clinical trials. The first HPV vaccine, Gardasil, was approved by the Food & Drug Administration (FDA) in 2006. It protected against four types of HPV: 6, 11,16, and 18. A second vaccine, Gardasil 9, was approved by the FDA in 2014. This vaccine protects against four further HPV strains, including HPV 31, 33, 45, 52, and 58. Gardasil 9 is the only HPV vaccine available in the United States today.
The Gardasil vaccines work by using the protein shell of each HPV strain. This shell does not contain viral RNA or DNA, so it causes an antibody response in the body but does not cause disease. The antibodies bind to the HPV virus and prevent the virus from infecting cells. The vaccine is administered in a series of two or three shots.
Before the first Gardasil vaccine was approved, it was thoroughly researched and went through several clinical trials over the course of ten years. The vaccine was tested on more than 20,000 females in 33 countries, and 4,000 males in 18 countries. Clinical trials showed that the Gardasil vaccine is nearly 100 percent effective in preventing cell abnormalities in the cervix by HPV strains 16 and 18. The studies also showed the vaccine is 90% effective in preventing genital warts and lesions from forming as the result of HPV strains 6, 11, 16, and 18.
Clinical trials on Gardasil 9 showed the vaccine is nearly 100 percent effective in preventing cell abnormalities by HPV strains 31, 33, 45, 52, and 58 as well. Further clinical trials have examined how effective Gardasil 9 is in different age groups. The studies have found that a greater immune response is created in younger adolescents. Therefore, it is recommended that boys and girls get vaccinated at age 11 to 12.
Vaccine rates vary greatly from state to state. In Minnesota, 65.7 percent of adolescents aged 13-17 were up to date with HPV vaccines in 2021. In the United States as a whole, 61.7 adolescents were up to date with HPV vaccines in 2021. Studies have shown that cervical cancer rates have declined since the HPV vaccine was introduced.
Cervical Cancer Awareness Month is an important time to learn about cervical cancer and ensure that you are up to date on screening and vaccination to best protect yourself and prevent cervical cancer. If you have questions or want to learn more about cervical cancer prevention, speak to your doctor to find out what is best for you and your health.