Exhibit 3.337

PAGE 1

     I, JEFFREY W. BULLOCK, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY CERTIFY THE ATTACHED ARE TRUE AND CORRECT COPIES OF ALL DOCUMENTS ON FILE OF “RIVERTON ONCOLOGY PRACTICE, LLC” AS RECEIVED AND FILED IN THIS OFFICE.

     THE FOLLOWING DOCUMENTS HAVE BEEN CERTIFIED:

     CERTIFICATE OF FORMATION, FILED THE NINTH DAY OF DECEMBER, A.D. 2008, AT 4:40 O’CLOCK P.M.

     AND I DO HEREBY FURTHER CERTIFY THAT THE AFORESAID CERTIFICATES ARE THE ONLY CERTIFICATES ON RECORD OF THE AFORESAID LIMITED LIABILITY COMPANY, “RIVERTON ONCOLOGY PRACTICE, LLC”.

		/s/ Jeffrey W. Bullock  Jeffrey W. Bullock, Secretary of State AUTHENTICATION: 8620295 DATE: 03-14-11
4631489 8100H 110292948

You may verify this certificate online
at corp.delaware.gov/authver.shtml

State of Delaware
Secretary of State
Division of Corporations
Delivered 06:39 PM 12/09/2008
FILED 04:40 PM 12/09/2008
SRV 081179011 - 4631489 FILE

Certificate of Formation
of
Riverton Oncology Practice, LLC

     The undersigned, an authorized natural person, for the purpose of forming a limited liability company, under the provisions and subject to the requirements of the State of Delaware, particularly Chapter 18, Title 6 of the Delaware Code and the acts amendatory thereof and supplemental thereto, and known, identified, and referred to as the Delaware Limited Liability Company Act (the “Act”), hereby certifies that:

     FIRST: The name of the limited liability company is Riverton Oncology Practice, LLC (the “Company”).

     SECOND: The address of the registered office and the name and address of the registered agent of the Company required to be maintained by Section 18-104 of the Act is The Corporation Trust Company, Corporation Trust Center, 1209 Orange Street, Wilmington, Delaware 19801.

     IN WITNESS WHEREOF, the undersigned has executed this Certificate of Formation as of December 9, 2008.

By:	/s/ Mary Kim E. Shipp
	Mary Kim E. Shipp
	Authorized Person