Can a virus test replace the traditional test for cervical cancer?

TeachableMedicalNews article 08122021

Teachable moment in classrooms:

1. cellular basis of life chapter – mitosis, cell cycle controls to limit cell division
2. reproductive system chapter – anatomy of the female reproductive system
3. tissues chapter – epithelium that lines the female reproductive system
4. microbiology – human papilloma viruses

The news item:  Recently the following report about cervical cancer testing appeared:

Are Pap smears ‘obsolete’? There’s a better option for cervical cancer screening, American Cancer Society says

The American Cancer Society released new guidelines on cervical cancer screenings Thursday, recommending that people with a cervix start testing at age 25.

The article describes the debate whether the HPV test could replace the Pap smear test. The article states that despite the Pap smear testing, there are over 13,000 new cervical cancer cases per year, and there are over 4,000 deaths. The article also states that the HPV test is screening for human papilloma virus, and the Pap test is screening for cancerous cells.

So, Why Do I Care??  Cervical cancer is a deadly cancer, as the article stated from a yearly 13,000 new diagnoses there are over 4,000 deaths.  While vaccination has been available against cervical cancer, a better diagnostic method is still needed until everyone is vaccinated.

Plain English, Please!!!

First, let’s talk about what cervical cancer is. The narrow, tube-shaped part of the uterus, the cervix, opens into the vagina. The cervix has a thin lining epithelium, and that cell layer is where cancerous changes can take place.  Most cervical cancers start from that cervical epithelium.

Second, let’s talk about how the Pap smear works. In the 1950s Dr. Papanicolaou devised a procedure where he collected cells that were brushed, nudged off the cervix, and he then stained the cells to study them under the microscope. His studies showed that if abnormal cells with a large nucleus can be seen under the microscope, they may be an early sign of cervical cancer.  Today’s Pap smear is a modern version of Dr. Papanicolaou’s test.

Third, let’s talk about why we want to test the cervix for HPV. In the 1980s it became clear that cervical cancers are caused mainly by infection with a few types of HPV (strains 16 and 18). Normal epithelial cell of the cervix rarely divide, because their progress from G₀ phase of the cell cycle into the G₁ phase is blocked by several molecular traffic lights set to red. Imagine that you are driving on a street, and a red traffic light stops you for months. Infection of the cells by HPV reprograms many red lights to turn green, so the cells now progress into the G₁ phase of cell cycle, and then through the steps of mitosis. This explains why the Pap smear testing can identify the larger than normal nucleus holding extra DNA in the interphase and prophase.

Fourth, let’s talk about how the HPV screening test works. To test for HPV, cervical cells are collected very similarly to the Pap testing. The cells are dissolved, and their DNA or RNA is tested for the presence of HPV viral DNA or RNA using molecular biology techniques. The HPV test currently only compliments the Pap smear test, but there are serious discussions to use the HPV test as the main test for cervical cancer.