Cervical Cancer Screening in Low Resource Settings: Using Visual Inspection With Acetic Acid

Katherine Camacho Carr, CNM, PhD; John W. Sellors, MD

J Midwifery Womens Health. 2004;49(4)

Natural History of Cervical Cancer

An understanding of the natural history of cervical cancer is helpful in planning, implementing, and evaluating a cervical cancer prevention program in low resource settings. A primary prevention approach to cervical cancer presents greater challenges than other STIs, which can be prevented through safe sex practices such as regular use of condoms. Although male and female condoms offer some protection, skin-to-skin contact still allows for infection with HPV.^[10] An effective vaccine could protect women from the most common cancer-producing HPV types.^[16] However, types may vary by geographic region, and the degree of oncogenicity of various types remains unclear.^[13] Even if effective multivalent vaccines become available to protect women from the major oncogenic types of HPV, vaccination programs may be cost prohibitive and yield delayed benefits only after 20 to 30 years of prophylactic vaccination.

It is not unusual for several types of HPV to cause precursor lesions of the cervix, which we refer to as CIN. The CIN is epithelial cellular change, where the ratio of the cell nucleus to the size of the cell is increased; CIN is graded as CIN I (mild), CIN II (moderate), or CIN III (severe). CIN usually occurs in the transformation zone of the cervix near the squamocolumnar junction where the columnar epithelium of the endocervix and the squamous epithelium of the ectocervix meet. The transformation zone is the critical area to sample when performing cytology collection or to observe during a visual screening procedure. Figure 1 shows the transformation zone.

(Enlarge Image)

Figure 1.

Transformation zone of the cervix. Used with permission from Program for Appropriate Technology in Health (PATH). Seattle, WA: PATH.

Early cervical cancer prevention programs were based on the premise that cervical disease develops from precursor lesions, which progress from mild to moderate to severe CIN and then to cancer.^[9] It appears that CIN progresses to cancer over a prolonged period of time, usually 7 to 20 years and is asymptomatic.^[9,14] It can only be detected by a test. It is important that any moderate or severe CIN is treated, because a sizeable proportion may progress to cancer.^[15] Mild CIN may spontaneously regress or persist, especially in young women, although among these women progression to a higher grade is less common.^[9,14] Therefore, if resources permit, the woman's condition may be monitored, rather than treated.^[9,13] Table 2 summarizes the natural history of cervical cancer and outlines possible prevention and management guidelines.^[4,9]

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Table 1. Table 1. Classification of Cervical Intraepithelial Neoplasia and Cytologic Findings
CIN Classification	Bethesda 2001 Cytologic Terminology*
	ASC-US
	ASC-H
HPV effect	LSIL
CIN I	LSIL
CIN II	HSIL
CIN III	HSIL

CIN = cervical intraepithelial neoplasia; ASC-US=atypical cells of undetermined significance; ASC-H, atypical cells of undetermined significance, cannot exclude HSIL; LSIL, low-grade squamous intraepithelial lesions; HSIL=high-grade squamous intraepithelial lesions.
*Bethesda terminology from Solomon D et al.^[11]

Table 2. Table 2. Natural History, Management, and Prevention/Treatment Strategies for Cervical Cancer
	HPV Infection	Low-Grade CIN (I)	High-Grade CIN (II, III)	Invasive Cervical Cancer
Natural history	HPV exposure through sexual contact; can remain stable, lead to dysplasia, or become undetectable	HPV can cause low-grade lesions within months or years of infection. Usually temporary and disappear over time. Some cases may progress to high grade	HPV types can cause high-grade lesions directly or more rarely low-grade lesions that progress. Definite precursor lesion to cervical cancer	Develops over a period of years from high-grade lesions
Management	No treatment exists that eradicates HPV, and primary prevention with use of male or female condom offers partial protection	Monitor, unless there is concern about loss to follow-up; do not need to treat immediately because most lesions regress or do not progress	Treat, as most high-grade lesions progress to cervical cancer over time	Treatment is hospital-based and may not be curative if disease is in an advanced stage
Prevention and treatment	Counseling and education about HPV; safe sex practices. Vaccination in the future	Follow-up monitoring	Cryotherapy LEEP Conization	Hysterectomy Radiation Chemotherapy

Adapted with permission from Alliance for Cervical Cancer Prevention^[4] and Herdman C, Sherris J.^[9]

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