Rates of anal squamous cell carcinoma (SCC) and squamous carcinoma in situ (CIS) have increased strongly over time, in contrast to rates of anal adenocarcinoma (ADC), according to a study of data from the Surveillance, Epidemiology and End Results (SEER) program. Researchers found:

• Compared to men, women had higher rates of SCC (rate ratio (RR)=1.45) and lower rates of ADC (RR=0.68) and CIS (RR=0.36).

• Compared to non-Hispanic whites, blacks had lower rates of SCC (RR=0.82) and CIS (RR=0.90), but higher rates of ADC (RR=1.48).

• Anal cancer incidence rates (IRs) were higher in men and blacks age < 40 years.

• During 1992 to 2011, SCC IRs increased 2.9%/year, ADC IRs declined nonsignificantly, and CIS IRs rose 14.2%/year.

• SCC and ADC IR patterns and trends were similar across anal and rectal cancers.

Citation: Shiels MS, Kreimer AR, Coghill AE, Darragh TM, Devesa SS. Anal cancer incidence in the United States, 1977-2011: distinct patterns by histology and behavior. [Published online ahead of print July 29, 2015]. Cancer Epidemiol Biomarkers Prev. doi: 10.1158/1055-9965.EPI-15-0044.