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ine cervix during the past half-century is one of modern medicine’s most impressive success stories.Thanks largely to the widespread use of the Pap smear to screen asymptomatic women, the number of cervical cancer deaths declined in the U.S. by 74% between 1955 and 1992. Despite that decline, more than 12,000 cases of invasive cervical cancer are still diagnosed each year in this country, and more than 4000 women die of it. In developing countries that lack screening programs, the incidence of invasive cervical cancer still exceeds those of breast and lung cancer. For these reasons, researchers in gynecologic oncology have continued to seek a fuller understanding of this disease and to refine diagnostic methods for its early detection and treatment. The following pages contain a review of the anatomy and histology of the cervix, the causes and characteristics of cervical cancer, and current methods and recommendations for diagnosis and treatment. The nonpregnant adult uterus is roughly the size and shape of a pear. It rests on the floor of the pelvis with its conical narrower portion, the cervix (Latin, ‘neck’), pointing downward. The domelike top, or fundus, of the uterus lies between the rectum posteriorly and the urinary bladder anteriorly. Normally it tilts forward, resting on the top of the bladder and making a considerable angle with the axis of the vagina. From either side of the uterine fundus a hornlike projection gives rise to one of the two uterine tubes. Each of these sweeps laterally to form a funnel-shaped expansion near one of the ovaries. After ovulation, the oocyte travels a short distance through the pelvic cavity to enter the end of the adjacent uterine tube. Approximately the lower one-half of the cervix, the portio vaginalis (i.e., ‘vaginal portion’), extends down through the anterosuperior part of the vaginal vault to lie within the vagina. The upper half or portio supravaginalis, as its name implies, is above the vagina. Many physicians, evidently believing that portio means something like ‘porch’ or ‘portico’, omit the qualifying adjective and refer to the portio vaginalis simply as “the portio. ” A narrow passage (about 0.75 cm in diameter), the endocervical canal, runs through the cervix to connect the cavity of the uterus with the vagina. The upper end of this canal, opening into the uterine cavity, is called the internal os (Latin, ‘mouth’), and the lower end is the external os. After sexual intercourse, spermatozoa pass upward through the endocervical canal to traverse the uterine cavity and enter the uterine tube, where fertilization may take place if ovulation has occurred within the preceding 2-3 days. The body or corpus of the uterus consists largely of muscle (myometrium), whose contractions expel the fetus during childbirth. In contrast, the cervix contains mostly fibrous connective tissue rather than muscle. During labor and delivery the cervix is the first of three obstacles that the presenting part of the fetus must pass in order to be born, the others being the bony birth canal and the vulva. Before childbirth the external cervical os is a small round opening. Afterward it never quite regains that appearance but remains a somewhat gaping horizontal slit. Visual inspection of the cervix is an integral part of every gynecologic examination. Inspection is carried out with a vaginal speculum in place to separate the vaginal walls and with a bright light focused on the portio vaginalis. Vaginal specula are manufactured in various sizes and shapes to meet most needs. However, adequate visualization of the cervix may not be possible in prepubertal children, extremely obese women, or those with abnormal pelvic architecture. Cervical cancers arise in the epithelial cells that cover the portio vaginalis and line the endocervical canal. The cells of these two surfaces are essentially different. The portio vaginalis, like the vaginal walls, is covered by stratified squamous epithelium—scalelike or platelike epithelial cells arranged in several layers, creating a smooth, pale pink surface without mucous glands. In contrast, the cells lining the endocervical canal are simple columnar epithelium—a single layer of tall, cylindrical cells that secrete mucus. The surface here has a deeper reddish color and appears less smooth, partly because of the presence of many microscopic branched tubular glands that extend below the surface and are also lined with mucus-secreting simple columnar epithelium. The change from columnar to squamous cells occurs abruptly at the transition zone (TZ), also called the squamocolumnar junction (SCJ). This zone, which is grossly visible on examination of the cervix because of the contrasts in color and texture, occurs at approximately the level of the external os. When the transition zone lies at a lower level, as it often does in adolescents, a ring of columnar glandular epithelium is evident around the external os. This can sometimes be mistaken for cervical erosion or chronic cervicitis, but it is entirely benign and warrants no treatment. After menopause the transition zone may migrate higher into the endocervical Carcinoma of the Cervix