Pap test, also known as Pap smear or cervical screening, is a test that examines the cells of the cervix to detect any abnormal changes that may indicate cervical cancer or precancerous lesions. Pap test is one of the most effective methods of preventing cervical cancer, which is the fourth most common cancer among women worldwide. But how did this test come to be? In this text, we will explore the history of pap test from its origins in the 19th century to its modern developments in the 21st century.
The history of pap test begins with the discovery of cervical cancer and its causes. Cervical cancer is a malignant tumor that develops in the cervix, which is the lower part of the uterus that connects to the vagina. Cervical cancer can cause symptoms such as abnormal vaginal bleeding, pain, discharge, and infertility. If left untreated, cervical cancer can spread to other organs and tissues and cause death.
The first person to describe cervical cancer was Giovanni Battista Morgagni, an Italian anatomist and physician, who published his observations in 1761. He reported a case of a woman who died from a large ulcerated tumor in her cervix. He also noted that cervical cancer was more common in women who had multiple sexual partners or sexually transmitted diseases.
The first person to link cervical cancer to a specific cause was Rigoni-Stern, an Italian physician and statistician, who published his findings in 1842. He analyzed the mortality data of Verona, Italy, and found that cervical cancer was more prevalent among married women than among nuns or virgins. He concluded that cervical cancer was related to sexual intercourse and infection.
The first person to identify the infectious agent that causes cervical cancer was Harald zur Hausen, a German virologist and Nobel laureate, who published his hypothesis in 1976. He proposed that human papillomavirus (HPV), a group of viruses that infect the skin and mucous membranes, was responsible for cervical cancer. He based his hypothesis on the observation that HPV was found in genital warts, which were associated with cervical cancer. He also noted that HPV was sexually transmitted and could cause chronic infection and inflammation in the cervix.
The first person to prove the causal relationship between HPV and cervical cancer was Yuan Chang and Patrick Moore, two American virologists and Nobel laureates, who published their discovery in 1999. They used a technique called polymerase chain reaction (PCR) to detect the DNA of HPV in cervical cancer cells. They found that HPV type 16 and 18 were present in more than 70% of cervical cancer cases worldwide. They also showed that HPV could integrate into the host cell’s DNA and disrupt its normal function.
The Evolution of Pap Test: The Development of Screening Methods
The history of pap test continues with the development of screening methods that can detect cervical cancer or precancerous lesions before they become invasive or symptomatic. Screening methods are procedures that can examine a large population of asymptomatic individuals and identify those who are at risk of developing a disease or condition. Screening methods can help reduce the mortality and morbidity of a disease or condition by allowing early diagnosis and treatment.
The first screening method for cervical cancer was invented by George Papanicolaou, a Greek-American cytologist and physician, who published his technique in 1943. His technique involved scraping some cells from the cervix with a spatula or a brush and staining them with a special dye. The stained cells were then examined under a microscope to look for any abnormal changes in their shape, size, color, or arrangement. Papanicolaou’s technique was called the Papanicolaou test or Pap test.
The Pap test was widely adopted as a screening method for cervical cancer in the 1950s and 1960s. It proved to be effective in reducing the incidence and mortality of cervical cancer by detecting precancerous lesions that could be treated with surgery or other methods. However, the Pap test also had some limitations, such as low sensitivity (meaning it could miss some cases), high variability (meaning it could produce different results depending on the examiner or laboratory), and dependence on human interpretation (meaning it could be affected by human errors or biases).
The next screening method for cervical cancer was developed by Aurel Babeș, a Romanian microbiologist and physician, who published his technique in 1927. His technique involved applying a solution of acetic acid and iodine to the cervix and observing the color changes with a speculum. The normal cells would turn brown, while the abnormal cells would remain white or yellow. Babeș’s technique was called the Schiller test or iodine test.
The Schiller test was widely used as a screening method for cervical cancer in the 1930s and 1940s. It proved to be simple, cheap, and easy to perform. However, the Schiller test also had some limitations, such as low specificity (meaning it could produce false positives), high subjectivity (meaning it could be affected by the examiner’s judgment), and dependence on visual inspection (meaning it could miss some lesions that were not visible).
The next screening method for cervical cancer was invented by Hans Hinselmann, a German gynecologist and inventor, who published his device in 1925. His device was a colposcope, which is a magnifying instrument that allows viewing the cervix in detail. The colposcope can be used to examine the cervix after applying acetic acid or iodine, or after taking a Pap smear. The colposcope can also be used to perform biopsies or treatments on the cervix. Hinselmann’s technique was called colposcopy.
Colposcopy was widely used as a screening method for cervical cancer in the 1950s and 1960s. It proved to be useful in confirming the results of Pap test or Schiller test, as well as in detecting and treating precancerous lesions. However, colposcopy also had some limitations, such as high cost, high complexity, and low availability.
The modern screening methods for cervical cancer are based on the combination of cytology, histology, and molecular biology. These methods can detect cervical cancer or precancerous lesions with high accuracy and sensitivity, as well as identify the risk factors and causes of cervical cancer. Some examples of these methods are liquid-based cytology, HPV testing, HPV vaccination, and biomarker testing.
Recently, automated microscopes have appeared that perform the pap test automatically. Microscope scans the slide and generates digital image, then analyzes it by the means of AI. Benefits of AI:
- Improving the accuracy and consistency of pap. AI can use algorithms that are trained on large databases of cervical cell images from different sources and conditions. These algorithms can recognize and classify different types of cervical cells with high accuracy and consistency, regardless of the variations in staining quality, slide preparation, image quality, or operator skill. This can reduce the false negative and false positive rates of pap, as well as the variability and subjectivity of human interpretation.
- Increasing the speed and efficiency of pap. AI can process and analyze hundreds of cervical cell images in minutes, which is much faster than human examiners who can take hours or days. This can increase the productivity and capacity of pap laboratories and reduce the waiting time and workload for patients and staff.
- Enhancing the access and equity of pap. AI can reduce the cost and increase the availability of pap by eliminating or reducing the need for human examiners, who are often scarce, expensive, or inaccessible in some regions. This can also improve the access and equity of pap for underserved populations, such as rural areas, low-income countries, or marginalized groups.
- Advancing the knowledge and innovation of pap. AI can provide more information and insights about cervical cells and their changes than human examiners. AI can also identify new patterns, features, or biomarkers that may be relevant for cervical cancer or precancerous lesions. This can advance the knowledge and innovation of pap and contribute to the development of new methods, technologies, or treatments.
Pap test is a vital screening method that has a long history of development and innovation. From the discovery of cervical cancer to the development of screening methods, Pap test has evolved from a visual and manual method to a digital and automated one. Pap test can provide valuable information about the health status and disease prevention of women, as well as contribute to the advancement of medical science and technology.