Document:

<PAGE>

                                                                   EXHIBIT 10.27

                AMENDMENT NO. 1 TO FULL RECOURSE PROMISSORY NOTE

This Amendment No. 1, dated as of November 30, 2001, is entered into by and
among Exact Sciences Corporation, a Delaware corporation (the "Company") and Don
M. Hardison (the "Maker").

WHEREAS, the Maker entered into a Full Recourse Promissory Note with the Company
dated as of June 23, 2000 (the "Note"), the provisions of which grant the
Company and the Maker the right to amend the terms of the Note; and

         WHEREAS, in light of the decrease in market interest rates and to
encourage the Company's employees including the Maker to remain in the employ of
the Company, the Company desires to amend the interest rate on the Note and all
other promissory notes issued by the Company's employees to the Company to more
closely reflect current market interest rates.

         NOW, THEREFORE, in consideration of the promises and the agreements
         herein contained, and intending to be bound hereby, the parties hereby
         agree as follows: The first sentence of the first paragraph of the Note
         shall be amended and restated in its entirety to read as follows:

         "FOR VALUE RECEIVED, Don M. Hardison (the "Maker") promises to pay to
         the order of EXACT Sciences Corporation, a Delaware corporation (the
         "Holder"), at its principal office at 63 Great Road, Maynard,
         Massachusetts 01754, or such other place as may be designated from time
         to time in writing by the Holder, or its assigns, the principal sum of
         $299,999.38, together with accrued interest on the principal of this
         Note outstanding at the rate of 5% per year."

         In all other respects, the Note shall remain in full force and effect.

This Amendment No. 1 may be executed in any number of counterparts and by
different parties hereto in separate counterparts, with the same effect as if
all parties had signed the same document. All such counterparts shall be deemed
an original, shall be construed together and shall constitute one and the same
instrument.

                                  EXACT SCIENCES CORPORATION

                                  By:    /s/ John A. McCarthy Jr.
                                         ---------------------------------------
                                  Name:      John A. McCarthy Jr.
                                  Title:     Chief Operating Officer, Chief
                                             Financial Officer,
                                             Senior Executive Vice President
                                             and Treasurer
ACKNOWLEDGED AND AGREED

/s/ Don M. Hardison
---------------------------
    Don M. Hardison<PAGE>

                                                                   EXHIBIT 10.28

                AMENDMENT NO. 1 TO FULL RECOURSE PROMISSORY NOTE

This Amendment No. 1, dated as of November 30, 2001, is entered into by and
among Exact Sciences Corporation, a Delaware corporation (the "Company") and
John A. McCarthy Jr. (the "Maker").

WHEREAS, the Maker entered into a Full Recourse Promissory Note with the Company
dated as of November 30, 2000 (the "Note"), the provisions of which grant the
Company and the Maker the right to amend the terms of the Note; and

         WHEREAS, in light of the decrease in market interest rates and to
encourage the Company's employees including the Maker to remain in the employ of
the Company, the Company desires to amend the interest rate on the Note and all
other promissory notes issued by the Company's employees to the Company to more
closely reflect current market interest rates.

         NOW, THEREFORE, in consideration of the promises and the agreements
         herein contained, and intending to be bound hereby, the parties hereby
         agree as follows: The first sentence of the first paragraph of the Note
         shall be amended and restated in its entirety to read as follows:

         "FOR VALUE RECEIVED, John A. McCarthy Jr. (the "Maker") promises to pay
         to the order of EXACT Sciences Corporation, a Delaware corporation (the
         "Holder"), at its principal office at 63 Great Road, Maynard,
         Massachusetts 01754, or such other place as may be designated from time
         to time in writing by the Holder, or its assigns, the principal sum of
         $300,000, together with accrued interest on the principal of this Note
         outstanding at the rate of 5% per year."

         In all other respects, the Note shall remain in full force and effect.

This Amendment No. 1 may be executed in any number of counterparts and by
different parties hereto in separate counterparts, with the same effect as if
all parties had signed the same document. All such counterparts shall be deemed
an original, shall be construed together and shall constitute one and the same
instrument.

                                 EXACT SCIENCES CORPORATION

                                 By:   /s/ Don M. Hardison
                                       -----------------------------------------
                                 Name:     Don M. Hardison
                                 Title:    Chief Executive Officer and President
ACKNOWLEDGED AND AGREED

/s/ John A. McCarthy Jr.
-----------------------
    John A. McCarthy Jr.<Page>

                                                                 EXHIBIT 10.29

[GRAPHIC EXACT SCIENCES]
APPLYING GENOMICS TO ERADICATE CANCER(TM)

        OCTOBER 15, 2001

        EXECUTIVE CASH INCENTIVE PLAN

OVERVIEW

The EXACT Sciences Executive Cash Incentive Plan has been designed to be an
effective management tool that will bring crystal-clear focus to the company's
short term, fiscal year objectives and incentivize performance to not just meet,
but accelerate and overachieve the accomplishment of those objectives. The plan
is based on specific and measurable goals for both the company and each
individual participant, with performance against those to be weighted equally.
As a financial incentive, participants in the plan will have a significant
percentage of their annual total cash compensation tied to meeting the corporate
and individual objectives that have been established for the year with the
opportunity to receive greater payouts for overachievement.

METHODOLOGY

Many executive cash incentive programs are ineffective, particularly in early
stage companies that lack clear revenue or profit metrics and formulae upon
which to base performance payouts. The reason for this is generally that the
underlying goals are vague and overly subjective, if identified at all, or
change without being updated. This makes assessing performance against these
"goals" almost impossible and awards become made on a largely subjective basis.
The end result is that management receives its cash incentive for unclear
reasons, underlying critical corporate objectives remain under-achieved, and
after a short time the plan becomes a deferred compensation plan with "expected"
cash versus "incentive" cash. Not surprisingly, these companies often
under-perform and have little or no return-on-investment to show for their
incentive expense. This phenomenon is particularly distressing in companies that
lack profits to fund incentive plans and must rely on financings to sustain
their continued viability.

Management at EXACT however, strongly feels that a well-constructed and managed
executive incentive plan will drive both performance and shareholder value and
represents an effective investment of its cash resources. To ensure this result,
the EXACT plan has been designed with the following components:

GOALS

Critical to the success of any incentive plan is the ability to set specific and
measurable goals and only those that are tied to key success factors for the
company. To drive performance, it is also important that these goals "stretch"
the envelope at target, but are still attainable. Finally, the goals must not be
so numerous that they diminish focus.

The EXACT Executive Cash Incentive plan involves setting goals for both the
corporation and team as a whole and for each executive/functional area
individually. The company uses a common template for these goals
cross-functionally, which allows for consistent assessment and measurement (see
sample attached). Before implementation, both corporate and individual goals are
reviewed and approved by the

                                       1
<Page>

                                                                  EXACT Sciences
                                                   Executive Cash Incentive Plan
                                                                October 15, 2001

Leadership Team. The Board of Directors will also review corporate goals in
advance of the fiscal year. This process will help drive the establishment of
critical goals and facilitate the communication of clear direction with both the
Board and the management team.

It is also important to recognize that EXACT Sciences is an early stage company
and may be subject to some volatility. Plans and goals may change dynamically
and need to be updated. Also, achievements of great worth may occur that were
not initially envisioned, but which nonetheless prove to be very important.
These factors will also be considered as the plan is reviewed at year-end.

PERFORMANCE ASSESSMENT

After the end of each fiscal year, management will assess performance against
goals. On the corporate level, this will occur first by the management team, and
then between the CEO and the Board of Directors. At the executive level, the
initial review will be with the individual's manager and the CEO with the input
of the Leadership Team as appropriate. Key to the assessment of individual
performance is the understanding that the plan will show a relative distribution
of performance amongst the team. In any given year it is likely there will be
overachievers and under-performers.

PAYOUTS

For assessment, corporate performance against goals has been divided into four
levels: exceeds, achieves, achieves most, or misses. For individual performance
there are only two levels: effective or outstanding performance. Under the plan,
an individual must perform to be rewarded. No incentive payouts will be made to
individuals who do not achieve at least an effective level of performance
against goals regardless of the level of corporate performance.

After performance is assessed, payouts under the plan are calculated by using a
matrix that weights corporate and individual performance equally (see attached).
While this matrix outlines payouts as a percent of salary by position level, it
is possible that the CEO will make recommendations outside of these ranges to
the Compensation Committee.

If in any given year it is the decision of the management team, in concurrence
with the Board, that the financial resources of the company are inadequate to
support the plan regardless of performance, payouts may be restructured using
equity or deferred to such future date when financial resources can
appropriately accommodate them.

                                       2
<Page>

                                                                  EXACT Sciences
                                                   Executive Cash Incentive Plan
                                                                October 15, 2001

SUMMARY

-        Executive Cash Incentive Plan is an annual plan tied to the Fiscal Year
         beginning in Fiscal Year 2001 and continuing each Fiscal Year
         thereafter.

-        Participants in the plan are member of senior management including the
         CEO and all Vice Presidents. Participation may be expanded selectively
         to key Directors at lower payout levels. Executives who are hired
         mid-plan year will participate on a monthly, prorated basis.

-        Corporate goals are developed by management and reviewed by the Board
         of Directors prior to the beginning of each fiscal year. Corporate
         goals are the same for all executives.

-        Individual goals are established by the CEO, with the Leadership Team
         as appropriate, prior to the beginning of fiscal year or at the time of
         hire. These are specific to each individual.

-        At end of fiscal year, the CEO, with the Leadership Team as
         appropriate, assesses individual performance. Corporate performance is
         assessed occur first by the CEO and the Leadership Team and then
         between the CEO and the Board of Directors.

-        Payouts are driven by performance against objectives using a matrix
         format where corporate and individual performance are equally weighted.

-        The matrix outlines payouts as a percent of salary by position level.
         However, it is possible for the CEO to make recommendations outside of
         these ranges to the Compensation Committee.

-        For the purpose of assessing competitive total cash compensation,
         target payout at target performance is defined as Corporate Performance
         is at "Achieves all Goals" and Individual Performance is at
         "Effective". Target payouts vary as a percent of base salary generally
         as follows: CEO - 30% of base salary; Senior/Executive VP - 25% of base
         salary; VP - 20% of base salary. Target payouts may be adjusted within
         levels to reflect specific market data.

                                       3
<Page>

                                                                  EXACT Sciences
                                                   Executive Cash Incentive Plan
                                                                October 15, 2001

PAYOUT MATRICES BY LEVEL

<Table>
<Caption>

-------------------------------------------------------------------------------------------
CEO
-------------------------------------------------------------------------------------------
<S>                <C>                  <C>              <C>              <C>
Corporate          Exceeds Goals        25-35%           35-45%           Incentive Payout
Performance        ---------------------------------------------------     (of base salary)
                   Achieves All Goals   20-30%           30-35%
                   ---------------------------------------------------
                   Achieves Most Goals  10-15%           15-20%
                   ---------------------------------------------------
                   Misses Goals          0%               10%
-------------------------------------------------------------------------------------------
                                      Effective         Outstanding
                                   -----------------------------------
                                         Individual Performance
-------------------------------------------------------------------------------------------

<Caption>

-------------------------------------------------------------------------------------------
SENIOR - EXECUTIVE VICE PRESIDENT LEVEL
-------------------------------------------------------------------------------------------
<S>                <C>                  <C>              <C>              <C>
Corporate          Exceeds Goals        20-30%           30-40%           Incentive Payout
Performance        ---------------------------------------------------     (of base salary)
                   Achieves Goals       15-25%           25-30%
                   ---------------------------------------------------
                   Achieves Most Goals  5-10%             15%
                   ---------------------------------------------------
                   Misses Goals          0%               10%
-------------------------------------------------------------------------------------------
                                      Effective         Outstanding
                                   -----------------------------------
                                         Individual Performance
-------------------------------------------------------------------------------------------

<Caption>

-------------------------------------------------------------------------------------------
VICE PRESIDENT LEVEL
-------------------------------------------------------------------------------------------
<S>                <C>                  <C>              <C>              <C>
Corporate          Exceeds Goals        15-25%           25-35%           Incentive Payout
Performance        ---------------------------------------------------     (of base salary)
                   Achieves Goals       10-20%           20-25%
                   ---------------------------------------------------
                   Achieves Most Goals  5-10%             15%
                   ---------------------------------------------------
                   Misses Goals          0%               10%
-------------------------------------------------------------------------------------------
                                      Effective         Outstanding
                                   -----------------------------------
                                         Individual Performance
-------------------------------------------------------------------------------------------
</Table>

                                       4

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