Carcinoma of the cervix in Newark, New Jersey, 1970-76. A very low in situ: invasive ratio.

Both blacks and whites in Newark had significantly lowered incidences of in situ cervical cancer as compared to the Third National Cancer Survey (TNCS) population. In contrast, Newark blacks' invasive cancer rates were higher than those found in any individual geographic area surveyed in TNCS except for Minneapolis as compared to Newark whites, who had lower rates than all individual TNCS areas except Colorado and San Francisco. Newark blacks had a relative risk of 4.0 for invasive cancer as compared to Newark whites, whereas the corresponding relative risk for blacks versus whites in the TNCS population was 2.0. Newark blacks and whites together had the lowest in situ invasive ratio as compared to women in other parts of the United States. The invasive cancer incidence and mortality rates for both Newark blacks and whites were significantly higher than in the Surveillance, Epidemiology and End Results (SEER) population, but incidence:mortality ratios for Newark and SEER were not different. The most likely explanation for the low in situ rates and high invasive rates among Newark blacks is their failure to obtain Papanicolaou (Pap) smears. The low in situ rate among Newark whites in the absence of a high invasive rate is difficult to explain. It seems that the problem among blacks can be alleviated by the widespread use of Pap smears, which reduce the frequency of invasive cancer and the associated mortality.