Comprehensive Study Notes on Cytology and Cervical Cancer Prevention

Overview and Definition of Cytology

Cytology is defined as the study of cells collected as samples during various medical procedures. It involves the microscopic examination of these cells to exclude or confirm the presence of diseases, such as inflammation, infection, and neoplasia. In most medical systems globally, cytology is recognized as a specific branch of Anatomic Pathology.

A standard cytology test consists of four fundamental steps. First, the sample must be collected from the patient. Second, the laboratory processes and prepares the specimen for analysis. Third, the specimen is examined, either manually under a microscope or through digital imaging technologies. Finally, a laboratory report is generated to communicate the findings, although the reporting process itself is often external to the immediate clinical sample evaluation sequence.

Methods of Specimen Collection in Cytology

There are three primary methods used to collect cells for microscopic evaluation. The first method involves scraping or brushing the surface of a tissue. Common examples include Cervical (Pap) smears, bronchial brushings, esophageal brushings, ureteric brushings, and bile duct brushings. This technique can also be applied to oral lesions using specialized tools like a spatula or specialized brushes.

The second method is the collection of body fluids or discharge samples. These specimens include sputum, urine, joint fluid, cerebrospinal fluid ( $CSF$ ), and cyst fluids. It also encompasses effusions from the pleura, peritoneum, and pericardium. Once collected, these fluids are typically centrifuged in the laboratory to concentrate the cellular material into a sediment, which is then placed onto glass slides for microscopic review.

The third method is Fine Needle Aspiration ( $FNA$ ). This is used for both palpable superficial masses and deep-seated, non-palpable masses. Superficial targets include lymph nodes, the breast, thyroid, salivary glands, and various soft tissue masses. For deep organs such as the lung, liver, kidney, or pelvis, radiologic-guided $FNA$ is utilized. This involves using sonar or CT scans to provide real-time image guidance, ensuring the biopsy needle is accurately positioned within the lesion.

Comparison Between Cytology and Histology

Histology and cytology differ significantly in focus, scope, and technical detail. Histology is the study of animal and plant tissues under a microscope, focusing on tissues, organs, and organ systems. Cytology specifically focuses on the structure and functions of individual cells. While histology has a wider scope and provides critical information regarding tissue architecture, cytology has a narrower scope but provides excellent cellular details.

From a practical standpoint, histology generally involves a higher cost of study compared to the lower cost associated with cytology. Cytology offers several distinct advantages: it is less invasive, causes less discomfort and pain for the patient, and carries a lower risk of complications. Furthermore, cytology typically features a quicker turnaround time and is more cost-effective. It also allows for many ancillary tests to be performed on the collected material.

However, cytology has specific disadvantages. It cannot be used to diagnose conditions where the architectural arrangement of cells is the diagnostic hallmark, such as liver cirrhosis. Additionally, certain types of tumor grading, such as the accurate counting of mitoses, are less precise in cytologic samples. There is also the risk that the collected material may be insufficient for large panels of ancillary tests.

Etiology and Progression of Cervical Cancer

Cervical cancer is a significant global health burden, ranking as the $4^{th}$ most common cancer in women worldwide. In many Low-Middle Income Countries ( $LMIC$ ), it is the first or second most common cancer. It accounts for $7.5\%$ of all female cancer deaths globally, with the vast majority of these deaths occurring in $LMIC$ .

The primary cause of cervical cancer is infection with the Human Papillomavirus ( $HPV$ ). This virus causes a variety of genital lesions, ranging from common warts to invasive malignancy. While there are many strains of $HPV$ , at least $15$ are classified as High-Risk ( $HR$ ) types capable of causing cancer, including types $16, 18, 31, 33, 45, 52, 56, 59, 68, 73$ , and others. Other potential co-factors that may influence development include smoking, the presence of other sexually transmitted diseases ( $STDs$ ), and the state of the patient's immune system.

Most $HPV$ infections are transient and are successfully cleared by the body's immune system. However, if an infection persists, it can lead to cellular changes. These progress from Low-grade Squamous Intraepithelial Lesion ( $LSIL$ ), which represents minor changes, to High-grade Squamous Intraepithelial Lesion ( $HSIL$ ), which represents severe changes, and eventually to invasive cervical cancer.

Global and Local Prevention Strategies

Prevention is categorized into primary and secondary strategies. Primary prevention focuses on preventing the acquisition of $HPV$ through changing sexual practices and vaccination. Secondary prevention involves screening to detect and treat precursor lesions ( $LSIL$ and $HSIL$ ) before they develop into invasive cancer.

The World Health Organization ( $WHO$ ) has established a global strategy to reduce cervical cancer mortality to $4$ or fewer cases per $100,000$ women-years. To achieve this elimination goal by the year $2030$ , the $90\text{-}70\text{-}90$ targets have been set: $90\%$ of girls must be vaccinated with the $HPV$ vaccine by age $15$ ; $70\%$ of women must be screened with a high-quality test at ages $35$ and $45$ ; and $90\%$ of women diagnosed with cervical disease must receive treatment. Modeling suggests this could avert $74$ million new cases and avoid $62$ million deaths.

In South Africa, the $HPV$ vaccination program began in $2014$ , targeting girls in Grade $4$ (approximately $9$ years old) in public schools. This school-based program originally used a two-dose strategy. By $2024$ , the strategy shifted toward a single-dose regimen for girls aged $9$ years in both public and private schools. Recent studies indicate that a single dose provides efficient protection. The Gauteng Department of Health has scheduled a specific single-dose campaign from $8$ September to $07$ November $2025$ , targeting girls aged $9-15$ in Grade $5$ , with catch-up for Grades $6$ and $7$ .

Vaccine Types and Efficacy

There are currently three major $HPV$ vaccines on the market. Gardasil, produced by Merck and Co, targets types $16, 18, 6$ , and $11$ (where $6$ and $11$ cause genital warts). Cervarix, produced by GlaxoSmithKline, targets types $16$ and $18$ . Gardasil $9$ targets nine different $HPV$ types.

The vaccines consist of virus-like particles, which are empty shells of viral structural proteins that cannot transmit the virus. They are considered highly safe and efficacious. While the vaccines are estimated to eliminate between $40\%$ and $70\%$ of cervical cancers, screening remains necessary for women who were infected prior to vaccination or for those exposed to $HPV$ types not covered by the vaccines.

Screening and Secondary Prevention Tools

Secondary prevention relies on several diagnostic tools to identify precancerous lesions. $HR\,HPV$ tests offer excellent sensitivity but moderate specificity. Cytology, specifically Pap tests, offers moderate sensitivity but excellent specificity. Visual Inspection with Acetic Acid ( $VIA$ ) or with Lugol’s Iodine ( $VILI$ ) generally demonstrate moderate-to-poor sensitivity and specificity compared to molecular and cytologic methods.

Questions & Discussion

Revision Set 1

Examination of tissue sections under the microscope. T/F Answer: False (This describes histology).
Generally a more costly test than histopathology. T/F Answer: False (Cytology is generally more cost-effective).
Uses specimens collected in a minimally invasive manner. T/F Answer: True.

Revision Set 2

Cervical cancer is the most common cancer in women globally. T/F Answer: False (It is the $4^{th}$ most common globally).
Screening will still be required in women fully vaccinated with the $HPV$ vaccine. T/F Answer: True (Due to pre-existing infections or types not covered by the vaccine).
$WHO$ global strategy to implement by $2030$ includes $50\%$ of girls aged $15$ years and younger to receive $HPV$ vaccination. T/F Answer: False (The target is $90\%$ ).