Type 1 and type 2 cervical carcinomas: some cervical cancers are more difficult to prevent with screening

Although the Papanicolaou (Pap) smear is medical history's most successful cancer screening test, some cervical cancers are more difficult to prevent with screening than others. Cervical cancers that are difficult to prevent are seen disproportionately among interval cancers arising in previously screened women and in Pap test litigation. These include (i) rapidly progressing cervical cancers; (ii) cervical cancers in younger women; (iii) glandular cervical cancers; and (iv) cervical cancers in elderly women. Screening protocols have generally been designed to optimize prevention of slower-growing cervical squamous carcinomas in middle-aged women. To focus further attention on the heterogeneous screening challenges posed by different cervical cancers, we designate the more screening preventable majority as type 1 cervical cancers and the more difficult to prevent minority as type 2 cervical cancers. We review available data on why some cervical cancers are more difficult to prevent with screening and newer methods that may improve prevention.