**3. Natural history of cervical cancer**

#### **3.1. Histology**

Squamous epithelium and columnar epithelium are both types of epithelium lining in the surface of the cervix.

mild squamous dysplasia;

carcinoma in situ (CIS).

differentiation.

**4.1. Associated risk factors**

frequent intercourse;

venereal diseases;

**3.** Squamous cell carcinoma (SCC):

relationship to sexual intercourse; many partners during lifetime;

multiparity (several children) by mid 20s;

genital herpes (herpes simplex virus type 2—HSV-2);

post-coital or unexplained vaginal spotting or bleeding;

Adenocarcinomas of the cervix have a worse prognosis than squamous cell cancers.

race: incidence higher in blacks and Hispanics;

early onset of sexual activity; first pregnancy in teenage years;

human papilloma virus (HPV);

low socioeconomic status; poor genital hygiene; cigarette smoking;

peak incidence over 40 years.

persistent vaginal discharge;

Squamous cell carcinoma, adenocarcinoma:

**4.2. Signs and symptoms**

**4.3. Five-year survival rates**

pelvic pain.

Stage 0 = 100%; Stage I = 60–85%; Stage II = 40–60%;

flat condyloma; koilocytotic atypia; koilocytosis. **2.** High-grade squamous intraepithelial lesion (HSIL):

cervical intraepithelial neoplasia grade 2 (CIN2); cervical intraepithelial neoplasia grade 3 (CIN3);

a squamous lesion with high risk of developing into cancer;

an invasive epithelial tumour composed of squamous cells of varying degrees of

Introductory Chapter: Cervical Cancer - Screening, Treatment and Prevention

http://dx.doi.org/10.5772/intechopen.76907

5

Cervical cancer begins with abnormal changes in the cervical tissue. The risk of developing

these abnormal changes has been associated with the following factors:

The squamocolumnar junction is the junction between squamous epithelium and columnar epithelium and it migrates from the periphery of the ectocervix inward towards the external os and finally to the distal cervical canal when age increases.

The process by which the columnar epithelium is replaced by stratified squamous epithelium is termed as squamous metaplasia and the area where this transformation takes place is referred to as the transformation zone (IARC, 2005; WHO, 2006).

#### **3.2. The development of cervical cancer**

The cervix is protected by stratified squamous cell epithelium from injuries by toxins and from infections. The human papilloma virus (HPV) primarily targets the squamous cells, and persistent infection by the high-risk strains leads to change of cells to metaplasia and dysplasia, which is the precancer stage and this occurs in the transformation zone—TZ.

#### **3.3. The HPV epidemiology: HPV: The causal factor**

HPV16 and 18 are responsible for the development of all the precancers and invasive cancers of the uterine cervix.

HPV types: High-risk 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59; Low-risk 6, 11, 40, 42, 43, 44, 54, 61, 70, 72, 81.

#### **3.4. HPV transmission**

HPV transmission occurs through skin and mucous contact during sexual contact, and the cofactors are early sexual exposures and multiple partners.

Persistent HPV infections cause cervical cancers but most of the HPV infections are transient due to the protection from cell-mediated immunity.
