HPV: Relation SEX & CANCER

In my first post for Steemit, and as a senior cytotechnologyst (person who studies the cells), I would like to speak you about Human Papillomavirus (HPV). A virus that, in a silent way, is able to produce cancer and, despite of being quite unknown in our society, it’s very common.

HPV is a virus that belongs to the papillomaviridae family, with closed circular double-stranded DNA, oncogenic and a virus that infects highly differentiated tissues. There are more than 200 HPV types, being the genetic sequence known in around 100 types.

There are more than 30 types that can be spread trough direct sexual contact and are divided in two groups: HIGH and LOW oncogenic risk. High risk genotypes produce three types of lesions: low grade, high grade and lastly, invasive cancer. Low risk viruses produce low grade lesions as well as genital warts.

HPV infection is one of the most common sexually transmitted infections in the world, being able to cause cervical cancer (through vaginal sex), anal cancer (through anal sex infection) and andoropharyngeal cancer (through oral sex infection).

A great number of women are HPV infected at some point of their life. 50% of women between 15 and 19 years old that have initiated sexual activity are HPV positive in the first 5 years after starting sexual activity, 21% of women between 30 and 45 years old are positive and 14% women are HPV positive after 45 years.

The most of the times there is a spontaneous resolution of HPV infection, the immune system removes it without consequences, but between 10%-20% of the cases the infection is persistent and cause low grade lesions. These lesions can disappear, but when the infection persists, it can progress to high grade lesions, even cervical cancer if the lesion is not treated.

Since the patient is infected with the virus until the cancer appears there is a long period of time (between 10 and 20 years), and, until the cancer is produced, the disease goes through intermediate stages called preneoplastic lesions. In the cervix, these preneoplastic lesions can be treated with a surgery known as conization. It consists in removing surgically the affected tissue, avoiding the cancer development.

As you can see in illustration, there is a cellular transformation from a healthy tissue to an invasive cancer. We can observe that the lesion is occupying increasingly the healthy tissue up to occupy all the tissue density in the CIN 3. When the malignant cells cross the basement membrane (interpreted by the grey line) to disperse and enter new tissues, we’re talking about an invasive cancer.

For the detection of the preneoplastic lesions there are cervical cancer screening programs in developed countries. In these countries, the cervical cancer incidence is low thanks to these screening programs.

In the last decades there's been an increase in oropharyngeal cancer (tongue, tonsil...) HPV positive. In the same way that the virus attacks the cervical tissue, can infect the oral mucosa, and, with the virus persistence an oral cancer can be developed. Most of oral cancers are due to alcohol consumption and smoking, but HPV positive oral cancers have increased significantly.

A well-known case of HPV positive oropharyngeal cancer was the case of the actor Michael Douglas, who admitted that his cancer was due to an infection through oral sex. It is important to take into account that the majority of HPV infected people will not have cancer. Although oral sex with HPV infected people is related with oral cancer, the majority of infected people will not develop it, in the same way that the majority of smoking people will not develop a lung cancer, despite of being a risk factor.

As well as there are cervical screening programs, at the moment we don't have programs for oral cancer early detection, so, in the majority of cases, the disease is detected when is in advanced stages and there is metastasis in the lymph nodes.

It’s expected that in the next decades, in USA and Europe, will be more HPV positive oropharyngeal cancer than cervical cancer. Although, these tumors have better prognosis than alcohol/tobacco associated tumors, because they have better response to the treatment.

As a cytotechnologyst, I love the study of cells, so just to show you what’s my job like, I leave this image where you can see malignant squamous cells in a lymph node.

Images Credit [1] [2] [3] [4] [5] [6]