Cancer of the cervix is the third most common gynecologic malignancy in the United States. In 2009, a total of 11,270 new cases of cervical cancer and 4070 deaths were estimated (1). The incidence of this disease has decreased steadily over the past several decades. However, cervical cancer remains one of the most common cancers in women worldwide with approximately 490,000 new cases diagnosed each year and 275,000 related deaths (2). The areas with the highest incidence are Latin America, sub-Saharan Africa, and southern and southeastern Asia, while the areas with the lowest incidence are Western Europe, North America, the Middle East, and China (3). The incidence also varies by race and socioeconomic status, as it is higher in African Americans and Hispanics than in whites in the general population. Women in the lowest socioeconomic groups have the highest incidence of cervical cancer, due at least in part to inadequate screening. Generally, as Papanicolaou (Pap) screening has become more prevalent, preinvasive lesions of the cervix have been detected far more frequently than invasive cancer.
Squamous cell carcinoma (SCC) of the cervix may occur at any age from the second decade of life onward. The mean age at diagnosis is approximately 51 years, with the number of cases evenly divided between patients at 30 to 39 and 60 to 69 years of age (4). This represents a combination of earlier onset of sexual activity (ie, earlier acquisition of human papillomavirus [HPV] infection) and active Pap screening programs in the United States, which detect cancerous and precancerous lesions earlier in life. There has been an increase in the incidence of adenocarcinoma of the cervix compared with that of SCC over the past 2 decades (5), particularly among women below the age of 35 years (6,7). Adenocarcinoma (ACA) now makes up 15 to 25% of all invasive cervical cancers. This does not appear to be due to a relative decrease in SCC incidence caused by effective screening practices but rather an absolute increase in the incidence of adenocarcinoma and adenocarcinoma in situ (AIS) in younger women. Some have also hypothesized that this is due to an increase in oral contraceptive use, changes in the prevalence of HPV infection, or an increase in the reports of cervical cancer with this histology (8,9).
Etiology and Risk Factors
Epidemiologic studies have been examined for many possible explanations of the development of cervical cancer. Age at first intercourse, number of sexual partners, high parity, cigarette smoking, race, low socioeconomic status, and so on have been shown to be associated with an increased risk of cervical cancer (8,10,11). However, most of these factors have not been shown to be independent risk factors but rather are associated with sexual behavior and HPV infection, the latter ...