For Immediate Release

BOXBOROUGH, Mass., May 10, 2004 - Cytyc Corporation today announced that three studies evaluating the safety, efficacy and clinical performance of its NovaSure(R) System for endometrial ablation were presented last week at the 52nd Annual Clinical Meeting of the American College of Obstetricians and Gynecologists (ACOG) in Philadelphia. The studies describe a range of benefits including improved patient outcomes, improved patient satisfaction rates, and reduced operating room and recovery time.

A study by Richard Gimpelson, M.D., of St. Louis University School of Medicine, presented two- and three-year results from a multi-center clinical study that compared the efficacy of NovaSure endometrial ablation versus loop resection with rollerball ablation as the control. Results showed increased success rates with NovaSure as well as shorter procedure times. The author concluded that the NovaSure procedure yields high amenorrhea and patient satisfaction rates without the need for endometrial pretreatment. A second study comparing intraoperative and postoperative pain level in patients treated with the NovaSure System versus the ThermaChoice(R) UBT endometrial ablation technique, was presented by Philippe Laberge M.D., of Pavillon CHUL, Quebec, Canada. The results of the study indicate that patients treated with the NovaSure System experience significantly less intraoperative and postoperative pain than patients treated with the ThermaChoice UBT System.

Dr. Gimpelson also presented a study comparing four of the commercially available global endometrial ablation devices, based on the U.S. Food and Drug Administration (FDA) Summary of Safety and Effectiveness Data (SSED) for each device. The review included the NovaSure System, ThermaChoice UBT, HydroThermablator(R) and Her Option(R). The author concluded, "Based on SSED data, it appears that NovaSure yields the highest amenorrhea, success, and patients satisfaction rates" of the devices included in this study. NovaSure is also the only endometrial ablation system approved for use without endometrial pretreatment.

Cytyc also conducted an educational symposium titled "Endometrial Ablation: The Art of Managing Abnormal Uterine Bleeding." More than 300 physicians attended the symposium. The program outlined the pathophysiology, diagnosis and treatment options for abnormal uterine bleeding and presented a clinical overview of the NovaSure System. Endometrial ablation in an office setting was also discussed.

"The scientific evidence continues to confirm the benefits and advantages of the NovaSure System for endometrial ablation," said James Linder, M.D., Cytyc's chief medical officer. "We will continue to collect and present clinical data as we expand implementation of this innovative technology for the treatment of excessive menstrual bleeding."

It is estimated that as many as 7 million pre-menopausal women between the ages of 35-55 suffer from menorrhagia and 2.5 million women seek treatment for this condition each year. Current treatment options include hormone therapy, hysterectomy, and endometrial ablation. Published studies have demonstrated the clinical efficacy of the NovaSure System and the potential cost-effectiveness of endometrial ablation compared to hysterectomy.