Clinical Data for EXACT Sciences' PreGen-Plus Technology Presented at American College of Gastroenterology Annual Meeting.

Business Editors & Health/Medical Writers

MAYNARD, Mass.--(BUSINESS WIRE)--Oct. 23, 2002

Largest Study to Date Supports Point Sensitivity for Invasive Colorectal Cancer Substantially Higher than Other Non-Invasive Colorectal Cancer Screening Tests

EXACT Sciences Corporation (NASDAQ: EXAS) announced today that results from a clinical study of its PreGen-Plus(TM) technology indicate a point sensitivity of 64 percent for invasive colorectal cancer, which is greater than the point sensitivity for any other non-invasive colorectal cancer-screening test currently available. These data, which were described this morning in an oral presentation at the American College of Gastroenterology's ("ACG") Annual Meeting in Seattle, confirm earlier data from two other studies that were presented at the 2002 Digestive Disease Week conference ("DDW") held in May in San Francisco. The lead investigator for the study presented at the ACG is Dr. Sapna Syngal, of Boston's Brigham and Women's Hospital, who collaborated with EXACT Sciences and physicians at the Dana Farber Cancer Institute, Massachusetts General Hospital, Lahey Clinic Medical Center and Boston Medical Center, all of Massachusetts.

The study represents the single largest clinical study that has examined the performance of EXACT Sciences' proprietary fecal DNA technology. Dr. Syngal presented results for 61 patients, which, when combined with the patient data presented at DDW, brings the number of reported cancers analyzed by the PreGen-Plus technology to 125. Based on the two studies presented at DDW and the study presented this morning at the ACG, the sensitivity of PreGen-Plus for invasive colorectal cancer ranged between 64 - 67 percent, making it significantly more effective at detecting the presence of invasive cancers than any other non-invasive screening modality currently available. This sensitivity range appears to be equally applicable to both early- and late-stage cancers. The sporadic cancer patients in the study presented this morning at the ACG are representative of the population for which PreGen-Plus was developed, and which the American Cancer Society recommends be screened regularly for colorectal cancer.

The study also provided additional data on the ability of PreGen-Plus to detect advanced adenomas. The detection of advanced adenomas, and similar "pre-cancerous" lesions, allows a physician to diagnose and treat a patient before he or she ever develops invasive cancer. In the three studies presented to date, PreGen-Plus has indicated a sensitivity of greater than 50 percent for advanced adenomas. This sensitivity for advanced adenomas greatly enhances the clinical utility of PreGen-Plus, as there is no other non-invasive screening test that has the ability to consistently identify these lesions. The Company intends to continue to examine PreGen-Plus' sensitivity for advanced adenomas and invasive cancers in other clinical studies, including its 5,000-patient multi-center study, which is expected to complete enrollment in the first quarter of 2003.

"The results from this study confirm the earlier data we have seen on PreGen-Plus' performance," stated Don Hardison, EXACT Sciences' President and CEO. "All the data indicate a point sensitivity for PreGen-Plus of approximately 65 percent, which is higher than any of the non-invasive colorectal cancer screening tests that are currently available. In addition, the 50 percent sensitivity for advanced adenomas, although preliminary, is extremely exciting. If we continue to see this level of performance in other clinical studies, we will have the opportunity to achieve something even greater than our stated mission, which is to eradicate the mortality associated with colorectal cancer. If PreGen-Plus continues to indicate an ability to detect precancerous lesions at the rate we have seen to date, we actually may have the opportunity to prevent the development of the disease itself in patients who participate in a regular screening program."

PreGen-Plus is EXACT Sciences' non-invasive proprietary technology for the detection of colorectal cancer in the average-risk population. Currently, the American Cancer Society recommends that the 80 million Americans over the age of 50 should be screened regularly for colorectal cancer. If detected at an early stage, colorectal cancer has a cure rate of over 90 percent. Due to the inconvenience and discomfort associated with certain currently available screening methods, however, a majority of people avoid screening and therefore, most colorectal cancer cases are detected at a later stage, when the cure rate is less than 50 percent. It is estimated that approximately 150,000 Americans will be diagnosed with colorectal cancer in 2002, and 57,000 people will die from the disease. In June 2002, EXACT Sciences signed a strategic partnership agreement with Laboratory Corporation of America(R) Holdings (LabCorp(R)) for the commercialization of PreGen-Plus. EXACT Sciences and LabCorp expect that PreGen-Plus will be commercially available in the first half of 2003.

About EXACT Sciences Corporation

EXACT Sciences Corporation is an applied genomics company that has developed proprietary technologies that may be used for the early detection of several common cancers. EXACT Sciences has selected colorectal cancer as the first application of its technologies. Colorectal cancer is the most deadly cancer among non-smokers, and is curable if detected early. Despite the availability of colorectal cancer screening and diagnostic tests for more than 20 years, the rate of early detection of colorectal cancer remains low. EXACT Sciences believes its genomics-based technologies will enable early detection of colorectal cancer so that more people can be effectively treated. Founded in 1995, EXACT Sciences is based in Maynard, Mass. Detailed information on EXACT Sciences can be found on the World Wide Web at www.exactsciences.com.

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These statements are subject to a variety of risks and uncertainties, many of which are beyond EXACT Sciences' control, and which could cause actual results to differ materially from those contemplated in these forward-looking statements. In particular, the risks and uncertainties include, among other things, that the completion of clinical studies may not prove the superiority of EXACT Sciences' technologies, the inability to recruit a sufficient number of patients for clinical studies/trials, the inability to maintain business relationships with leading clinical reference laboratories to perform tests using EXACT Sciences' technologies, the failure of EXACT Sciences' collaborative partners to satisfy their obligations under agreements with the Company, the failure to convince medical practitioners to order tests using EXACT Sciences' technologies, the loss of support of key scientific collaborators, the failure to comply with federal and state statutes and regulations relating to EXACT Sciences' products and services, competition. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. EXACT Sciences undertakes no obligation to update or revise the information contained in this press release, whether as a result of new information, future events or circumstances or otherwise. For additional disclosure regarding the risks faced by EXACT Sciences, see the disclosure contained in EXACT Sciences' public filings with the Securities and Exchange Commission including, without limitation, its Form 10-K for the year ended December 31, 2001 and subsequent Forms 10-Q.