Is the Pap test a thing of the past?
Sunday, 27 April 2014
The distant past-The development of cervical cancer screening
George Papanikolaou, a Greek cytopathologist, invented the widely known “Pap Test” used worldwide for the detection of precancerous and cancerous conditions of the cervix.
In 1928, Dr Papanikolaou described his noninvasive technique of collecting cells from the female cervix and vagina, then smearing them on a glass slide and studying their cellular appearance.
One of his patients was a woman with uterine cancer whose smear clearly showed cancerous cells. Those cells, to his trained eye, were very different from those of normal women he had previously studied.
He described this observation as “one of the greatest thrills I ever experienced during my scientific career”.
In the years that followed, from 1928 to 1954, he published a paper on the value of vaginal smears in the diagnosis of uterine cancer and an illustrated monograph based on 3000 cases. This work was followed by “The Atlas of Exfoliative Cytology” giving birth to the new modern specialty of cytopathology.
The “pap smear” test was then widely adopted throughout the world and is still used today as a screening test for the diagnosis of precancerous and cancerous conditions of the cervix.
In diagnosing the pre-cancerous conditions early, the pre-cancer is not allowed to grow, metastasize and kill.
Cervical cancer is the 3rd most common gynecologic cancer diagnosis and cause of death among all gynecologic cancers in America. (Cancer statistics, 2014)
In countries without screening programs, cervical cancer is the 2nd most common type of cancer and the cause of cancer death among all types of cancer in women.
Interventions such as cryotherapy, LEEP excision, laser ablations and hysterectomy, treat the precancerous conditions and prevent the cancer from claiming women’s lives.
These treatments have afforded American women a decrease in the incidence of cervical cancer of nearly 70% in the last 30 years.
The current approach – Pap and HPV co-testing – Rationale for recommendations
In 1999, researchers from the Netherlands, using molecular techniques studied the presence of Human Papilloma Virus’ (HPV) genetic material in biopsies of invasive cervical cancers and found it to be present in 99.7% of the cases.
They titled their article “Human Papilloma Virus is a necessary cause of invasive cervical cancer worldwide”.
They suggested that HPV testing in addition to, or even instead of cervical cytology, should be performed in routine cervical screening.
HPV testing is now commercially available and can be used along with the “pap test” in women older than 30.
The presence of HPV’s viral material doesn’t mean though that there is pre-cancer present. Infection with the HPV is necessary but not enough to cause pre-cancer or cancer of the cervix.
Most HPV infections cause a mild abnormality and are temporary. The body clears the virus and is no longer present in the cervical cells.
Rarely, the virus persists. If the virus is present beyond the first or second year of testing, then the virus is likely to have taken hold of the biology of the cervical cells (like high jacking) and cause cervical cancer.
It is this persistence of the HPV over time, in repeated testing that signals the body’s inability to clear the virus.
In these situations, additional evaluations such as colposcopy need to be done to identify if the virus has caused precancerous conditions. If it has, then, minimally invasive treatment to remove the abnormality will restore the cervix back to normal.
The family of HPV has many viruses of varying capacity to cause cancer.
One way to think of them is as if they were a pack of wolves! There are leaders in that pack that cause most of the problems! The two worst ones are HPV 16 and HPV 18 which cause 60 % and 15% of the cervical cancers respectively worldwide.
There are also another 10 high risk, cancer causing viruses that HPV tests can identify.
The chance of developing HPV is about 80% in a woman’s life.
The most frequent infections are found in teenagers and women in their early twenties but because young women overall have strong immune systems, they can clear the virus to undetectable levels within 24 months of their initial detection.
So even if there is an infection with the HPV virus resulting in mild precancerous changes called LGSIL (low grade squamous intraepithelial neoplasia), these disappear due to the body’s ability to fight the virus and win!
The viruses that persist, do so because they are very oncogenic (able to cause cancer like HPV16 or 18), or because of other factors that decrease the immune system’s ability to protect the body against them, such as smoking, HIV infection and auto-immune conditions.
Current cervical cancer screening guidelines recommend:
- Women age 21-30 pap test every 3 years
- Women age 30 to 65 pap test and contesting with HPV every 5 years or pap alone every 3 years.
60 years after the introduction of the “pap test”, a newer version of the HPV test was recommended by an advisory panel to the FDA as a primary screening tool for cervical cancer screening and prevention.
Dr Dorothy Rosenthal, a Johns Hopkins professor and advisor to the FDA, noted that cervical cancer deaths have stopped declining and the new test will increase detection.
FDA recently (April 2014) approved the test that is now commercially available! Read more
“Move over pap test…..Here comes COBAS 4800 HPV”!!!
HPV primary screening with the COBAS HPV Test finds more advanced precancerous conditions than the Pap test alone and allows for efficient triage to colposcopy and eventual treatment.
For more information please read more.
The test is available in our office.
Please call for an appointment today!