A 52-year-old postmenopausal woman, presents for routine cervical cancer screening. She reports no significant gynecological history, and her last Pap test, performed five years ago, was normal. Maria has no history of abnormal Pap results or cervical procedures and no significant family history of gynecological cancers. She denies symptoms such as vaginal bleeding, discharge, or pain. The results of her Pap test indicate the absence of endocervical or transformation zone cells, although the sample is otherwise adequate. What is the clinical significance of the absence of endocervical cells in a Pap test?