The presence of endocervical transformation zone on a Pap smear means that it is a good sample in terms of the cells that the physician collected. The transition zone is the site where most cervical abnormalities such as cancer occur, according to the National Center for Biotechnology Information.
The Pap smear is an important screening test for cervical cancer and should be first scheduled at 21 years of age, explains MedlinePlus. When a Pap smear is taken, the physician makes sure to retrieve cells from the outside of the cervix and its opening next to the cervical canal. It is important for the sample to contain endocervical transition cells because of their role in cancer, according to the National Center for Biotechnology Information.
Sometimes Pap smear samples lack endocervical cells because the transition from the ectocervix to the endocervix varies in location from person to person, according to the National Center for Biotechnology Information. This can lead to cases where the Pap smear sample does not have the important components needed in screening for cervical cancer.
The emphasis on retrieving cells from the cervical transformation zone is that it is the site of highest susceptibility to cancer caused by the human papillomavirus virus. HPV-16 and HPV-18 are considered to be oncogenic and are the main targets of the recently developed HPV vaccines, explains Medscape.