Deleterious effects of formalin/acetic acid/alcohol (FAA) fixation on the detection of HPV DNA by in situ hybridization and the polymerase chain reaction.

As part of a study of archival cervical cancer specimens (1920s to 1980s) to determine whether changes have occurred in the prevalence of human papillomavirus (HPV) DNAs, investigations were performed on tissues which had been fixed in either 10% buffered formalin (NBF) or formalin-acetic acid-alcohol (FAA). HPV DNA was detected by in situ hybridization (ISH) using HPV 6, 11, 16 and 18 32P-labelled DNA probes under conditions of high stringency; and by the polymerase chain reaction (PCR) using 20-mer oligonucleotide primers to amplify 109 bases of the E6 region of HPV 16. In some instances results obtained from Southern blot hybridizations, which had been carried out on specimens of fresh cancer tissue, were available for comparison. When tissues had been fixed in NBF, HPV DNA sequences were detected in 53% of specimens by ISH and in 72% by PCR. In comparison, the rates of detection of HPV by ISH and PCR in tissues fixed in FAA were 17% and 21% respectively. These results indicate that FAA is clearly inferior to NBF for the preservation of detectable HPV DNA sequences in tissue sections.