HPV and Cervical Cancer
28 December 2021
What is HPV?
HPV a sexually transmitted disease caused by Human papillomavirus abbreviated as HPV is a DNA virus that commonly affects the population. There are many strains which are classified as low risk (eg., HPV 6,11, etc.) and high risk (eg., HPV 16,18,31,33, etc.) and about 30 strains infect the genitals. Persistent infection with the high-risk strains of the virus can lead to cancer mostly cervical cancer. Incidence of the infection is 1.0 to 5.5 million per year, sexually active men and women under the age of 25 has high rate of infection.
Signs and Symptoms
Majority of the time the infection goes unnoticed because they might be asymptomatic. Symptomatic individuals develop warts on their body or on the genital areas depending on the area of infection. The warts can be categorized as anogenital warts, common warts, plantar warts and flat warts in accordance to slight difference in their morphologies. Some immunocompromised individuals can develop cancers like cervical, anal, penile, head and neck, skin and lung cancer.
The virus gains entry into the body via micro-abrasions and can only infect the basal cells of stratified epithelium containing receptors like Lamins, integrins and Annexin A2. It is transmitted mainly by skin to skin contact like sexual intercourse, during childbirth, direct contact through small cuts. It can also be transmitted asexually via fomites and asymptomatic shedding.
Risk factors like sexual activity at young age, polygamy, damaged skin, smoking, alcohol consumption, presence of other sexually transmitted disease, weakened immune system or other comorbidities can increase the likelihood of contracting the disease.
Cervical Cancer induced by HPV
As mentioned earlier the most common and prevalent form of HPV induced cancer is cervical cancer. Persistent infection with high-risk HPV 16 and 18 strains is primarily responsible for cervical cancers in 70% cases. It infects the epithelial cells and multiplies only in epithelial cells leading to change in normal cellular morphology. Most infections are cleared out by immune system therefore only in people with weakened immune system and persistent infection, the virus is capable of turning on its oncogene to produce oncogenic proteins while switching off its own tumor suppressing gene. This in turn tampers the host cellular metabolic events in such a way that they proliferate indefinitely, escapes apoptosis and become cancerous. Having stated these facts, it is a universal truth that this is a slow and gradual process and takes time to develop into Cervical cell carcinoma. Therefore, cervical cancer could be prevented before the cells become cancers in women. How is that possible? There are series of signs and symptoms indicating cervical health issues that include abnormal bleeding especially after intercourse or menopause, unusual white discharge, painful intercourse, pain in the pelvic region, etc. Severe forms include swelling of legs, hematuria or problems urinating or having a bowel movement. Although these signs and symptoms might not be related to cervical cancer only, but people experiencing these are highly recommended to visit the doctor immediately.
To avoid development of cervical cancer, women above the age 30 are advised to do a Pap test if not once every year, then at least once every five years. What is Pap test? The Pap test or the Papanicolaou test is a method of screening to detect precancerous or cancerous cells in the cervix. If negative then normal cells detected and if the test is positive then there is presence of abnormal cells, although not necessarily cancer cells the doctor will do confirmatory tests like colposcopic biopsy or endocervical curettage to diagnose the problem. The terms used to elucidate the Pap smear result and help plan further diagnostic test and treatment are as follows:
Atypical squamous cells of undetermined significance (ASCUS) – Indicate slightly abnormal squamous cells but not necessarily precancerous cells therefore additional test for the presence of HPV virus is done to confirm the same.
Squamous intraepithelial lesion – Deviations in size, shape and characteristics are compared and segregated as low grade and high grade. Low grade deviation means more time to develop into cancer whereas high grade deviation means very less time for progression to cancerous stage.
Atypical glandular cells – these are cells that secrete mucus in the cervix and their morphology is slightly abnormal making it difficult to identify the stage of the cell.
Squamous Cell Cancer or adenocarcinoma cells – Definite stage of cancer where the cell morphology is completely abnormal.
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