For Immediate Release

BOXBOROUGH, Mass. & VAN NUYS, Calif., Mar 4, 2004 - Cytyc Corporation and PathNet Esoteric Laboratory Institute (PathNet), one of the nation's largest laboratories providing testing for underserved women nationwide, today announced that PathNet intends to convert all Pap tests to the ThinPrep(R) Pap Test. PathNet processes approximately 300,000 Pap tests annually and is the leading provider of Pap testing for underserved women in need of cervical cancer screening.

"We initially implemented the ThinPrep Pap Test in 1998. Our own data and the weight of the published evidence clearly show the clinical benefits of the ThinPrep Pap Test," said Alan Kaye, President of PathNet. "We believe it is in the best interest of our patients to standardize using this proven technology so that all patients, insured and uninsured, are provided the same standard of care."

"We must continue to educate and emphasize to women the importance of regular cervical cancer screening," said Juan Felix, M.D., PathNet's Medical Director. "However, we must also recognize that many of our patients cannot or will not come in for regular screening. It is especially important that these patients have access to the most accurate screening technology available."

"For years, PathNet has provided an invaluable service to many underserved patients in the United States. We applaud their commitment to convert all cervical cancer screening to the ThinPrep Pap Test so that their patients can benefit from our clinically proven technology," said Patrick J. Sullivan, Cytyc's chairman, president, and chief executive officer.

PathNet Esoteric Laboratory Institute is a privately held niche provider for Women's Health laboratory medicine data and information. PathNet provides specialty testing in the fields of cytopathology, sexually transmitted disease (STD) screening, molecular diagnostics, and genetic screening. With facilities in Texas and California, PathNet provides services to clinicians and clinics nationwide.