Cervical Cancer Awareness Month: History of the First Cancer Screening Test
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. HPV causes about 90 percent of cervical cancers, and it is preventable through HPV vaccination.
In 2021, it is estimated that about 14,000 new cervical cancer cases were diagnosed in the United States. About 4,000 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. 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. In 1916, Greek scientist Georgios Papanicolaou, considered the father of cytology (the study and examination of single cell types to diagnose disease), was studying the sex chromosomes and physiology of guinea pigs at New York University’s Pathology Department and Cornell University Medical College’s Anatomy Department. Papanicolaou described cytological patterns and physiological changes in vaginal samples from guinea pigs, and he thought his findings may be relevant to human physiology and the human reproductive system as well.
In the 1920s, Papanicolaou studied samples from human volunteers and discovered normal and malignant cell differences when cells swabbed from the cervix were examined under a microscope. Papanicolaou presented his findings in 1928, but other scientists rejected his research, largely based on errors and misspellings because Papanicolaou was still learning English after immigrating to the United States, as well as the commonly held belief that cells could not be used to diagnose cervical cancer.
Despite this rejection, Papanicolaou continued to study cervical cancer and to develop his screening method. In 1939, he collaborated with gynecologists Drs. Herbert Traut and Andrew Marchetti on a clinical trial to study Papanicolaou’s screening test. Over three years, the researchers tested the cervical cancer screening test on more than 3,000 women. The researchers diagnosed 179 cases of cancer, 127 of which were 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. Papanicolaou and Traut published the study’s results in 1941 and 1943.
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
Researchers are still examining the effectiveness of HPV tests and other screening methods, as well as screening guidelines for individuals based on risk factors. For Cervical Cancer Awareness Month, remember to speak to your doctor to find out what is best for you and your health and to check if you are up to date on cervical cancer screening.