POWER OF ATTORNEY

	The undersigned hereby constitutes and appoints each of D. Scott Coward, Mark
Busch and Kyle Stacey, signing singly, as the undersigned's true and lawful
attorney-in-fact to:

	(1)	execute for and on behalf of the undersigned, in the undersigned's capacity
as a director of Exact Sciences Corporation (the "Company"), Forms 3, 4 and 5 in
accordance with Section 16(a) of the Securities Exchange Act of 1934 and the
rules thereunder (the "Exchange Act"), as well as the Form ID to obtain and/or
renew EDGAR codes for use in connection with the filing of Forms 3, 4 and 5 and
any other related documentation;

	(2)	do and perform any and all acts for and on behalf of the undersigned which
may be necessary or desirable to complete and execute any such Forms 3, 4 or 5,
Form ID or other related documentation, complete and execute any amendment or
amendments thereto, and timely file such forms or documentation with the United
States Securities and Exchange Commission and any stock exchange or similar
authority;

	(3)	take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned pursuant to this Power of Attorney shall be in such form and shall
contain such terms and conditions as such attorney-in-fact may approve in such
attorney-in-fact's discretion; and

	(4)	in connection with the preparation and filing of Forms 3, 4 and 5, seek or
obtain, as the undersigned's attorney-in-fact and on the undersigned's behalf,
information regarding transactions in the Company's securities from any third
party, including brokers, employee benefit plan administrators and trustees, and
the undersigned hereby authorizes any such person to release any such
information to such attorney-in-fact and approves and ratifies any such release
of information.

	The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary, or proper to be done in connection with the exercise of any of the
rights and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of
substitution or revocation, herby ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this Power of Attorney and the
rights and powers herein granted.  The undersigned acknowledges that the
foregoing attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming, nor is the Company assuming, any of the
undersigned's responsibilities to comply with Section 16 of the Exchange Act.

	This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

	This Power of Attorney does not relieve the undersigned from responsibility for
compliance with the undersigned's obligations under the Exchange Act, including,
without limitation, the reporting requirements under Section 16 of the Exchange
Act.  Additionally, although pursuant to this Power of Attorney the Company will
use commercially reasonable best efforts to timely and accurately file Section
16 reports on behalf of the undersigned, the Company does not represent or
warrant that it will be able to in all cases timely and accurately file Section
16 reports on behalf of the undersigned due to various factors, including, but
not limited to, the shorter deadlines mandated by the Sarbanes-Oxley Act of
2002, possible time zone differences between the Company and the undersigned and
the Company's need to rely on other parties for information, including the
undersigned and brokers of the undersigned.

	IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 19th day of October, 2017.


/s/ Eli Casdin
Eli Casdin