Twelve Studies Evaluating Cytyc's MammoSite(R) Radiation Therapy System Presented at ASTRO Annual Meeting.

MARLBOROUGH, Mass. -- Cytyc Corporation (Nasdaq: CYTC), a leading provider of surgical and diagnostic products targeting cancer diagnostics and women's health, today announced that twelve studies presenting data on the MammoSite([R]) Radiation Therapy System (RTS) were featured at the 48th Annual Meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO) in Philadelphia. The studies evaluated a range of parameters including insertion techniques, treatment efficacy, toxicity rates, and cosmetic results. The studies presented included single institutional experiences as well as multi-site evaluations. Among the data presented were:

A study by Prestige et al., from the Texas Cancer Clinic in San Antonio, evaluated the local control, cosmetic results, and complication rates of MammoSite brachytherapy for early stage breast cancer. In total, 234 patients were treated between May 2002 and January 2006. The authors reported an "in-breast" recurrence rate of 0.8 percent with a median follow-up of 21 months. The data showed that 78 percent of patients judged their cosmesis as "excellent," 16 percent as "good," and none judged cosmetic results as "poor." The authors concluded that these data support the efficacy of MammoSite RTS in women with early stage breast cancer.

Keisch et al., reported on a subset of patients with ductal carcinoma in situ (DCIS) enrolled in a multi-center registry trial under the auspices of the American Society of Breast Surgeons (ASBS). From May 2002 to July 2004, 194 patients with DCIS undergoing breast conserving therapy were treated with the MammoSite RTS. In patients with two or greater years of follow up, the "in-breast" recurrence rate was 0.9 percent with an excellent/good cosmesis rate of 94 percent. The authors concluded that treating DCIS patients with MammoSite RTS results in acceptable toxicity and outcomes consistent with external whole breast radiation.

Cuttino et al., presented results from a multi-institutional study evaluating the clinical experience of the MammoSite RTS. Nine institutions participated and 483 patients with breast cancer were treated with accelerated partial breast irradiation (APBI) using the MammoSite RTS. The data from all sites were pooled. The author reported an "in-breast" failure rate of 1.2 percent with a median follow-up time of 24 months. Cosmetic results were good/excellent in 91 percent of patients and toxicity rates were acceptable.

"We are very encouraged by scientific data reporting on the performance of the MammoSite Radiation Therapy System in clinical settings at this meeting. These reports remain consistent with earlier reports demonstrating very low rates of local recurrence, good to excellent cosmetic results in the majority of patients with very acceptable rates of toxicity," said Ellen Sheets, M.D., Cytyc's chief medical officer. "We believe that as clinicians share their experiences with this technology with their peers, more and more patients will have access to MammoSite RTS."

Cytyc Corporation is a leading provider of best-in-class medical technology that enables physicians and laboratories to improve patients' lives throughout the world. Cytyc provides diagnostic and minimally invasive surgical products targeting cancer and women's health. The ThinPrep([R]) System is the most widely used method for cervical cancer screening in the United States. The ThinPrep System consists of the ThinPrep([R]) 2000 Processor, ThinPrep([R])3000 Processor, ThinPrep([R]) Imaging System, and related reagents, filters, and other supplies. The ThinPrep System also provides the platform from which the Company launched its expansion into breast cancer risk assessment with the FirstCyte([R]) Breast Test. The NovaSure([R]) Impedance Controlled Endometrial Ablation System, or the NovaSure([R]) System, is an innovative endometrial ablation device to treat menorrhagia, or excessive menstrual bleeding. The MammoSite([R]) Radiation Therapy System is a single-use device for the treatment of breast cancer that positions radiation sources directly into the post-lumpectomy site to optimize radiation treatment delivery while minimizing damage to healthy tissue. The GliaSite([R]) Radiation Therapy System is for the treatment of malignant brain tumors.

Cytyc is traded on The Nasdaq Stock Market under the symbol CYTC. Cytyc, ThinPrep, FirstCyte, NovaSure, MammoSite, and GliaSite are registered trademarks of Cytyc Corporation.

Forward-looking statements in this press release are made pursuant to the provisions of Section 21E of the Securities Exchange Act of 1934. Investors are cautioned that statements in this press release which are not strictly historical statements, including, without limitation, statements relating to Cytyc's future financial condition, operating results and economic performance, and management's expectations regarding key customer relationships, future growth opportunities, product acceptance and business strategy, constitute forward-looking statements. These statements are based on current expectations, forecasts and assumptions that are subject to risks and uncertainties, which could cause actual outcomes and results to differ materially from those statements. Risks and uncertainties include, among others, dependence on key personnel and customers as well as reliance on proprietary technology, uncertainty of product development efforts and timelines, management of growth, product diversification, and organizational change, entry into new market segments domestically and new markets internationally, risks associated with litigation, the effective integration of acquired businesses and technologies, competition and competitive pricing pressures, risks associated with the FDA regulatory approval processes and healthcare reimbursement policies in the United States and abroad, introduction of technologies that are disruptive to Cytyc's business and operations, the impact of new accounting requirements and governmental rules and regulations, as well as other risks detailed in Cytyc's filings with the Securities and Exchange Commission, including those under the heading "Risk Factors" in its 2005 Annual Report on Form 10-K and its most recent Quarterly Report on Form 10-Q filed with the Commission. Cytyc cautions readers not to place undue reliance on any such forward-looking statements, which speak only as of the date they were made. Cytyc disclaims any obligation to publicly update or revise any such statements to reflect any change in its expectations or events, conditions, or circumstances on which any such statements may be based, or that may affect the likelihood that actual results will differ from those set forth in the forward-looking statements.