Exhibit 99.1

21ST CENTURY ONCOLOGY HOLDINGS, INC.

21ST CENTURY ONCOLOGY HOLDINGS INC. REPORTS FOURTH QUARTER AND FULL YEAR 2014 FINANCIAL RESULTS

Fourth Quarter 2014 Highlights:

·                  Total pro-forma revenues of $269.5  million, a 28.8% year-over-year increase

·                  7th consecutive quarter of growth in same store freestanding treatments per day, up 2.3% year-over-year

·                  4th consecutive quarter of Pro Forma Adjusted EBITDA margin expansion — 13.8% of total pro-forma revenues

·                  International cases increased 5.0% versus prior year period

·                  OnCure Holdings, Inc. (“Oncure”) and South Florida Radiation Oncology (“SFRO”) continue to perform ahead of expectations

Full Year 2014 Highlights:

·                  Pro-forma revenues surpass $1.0 billion, increasing 22.5%

·                  Domestic same store treatments per day increased 2.6%

·                  International revenues approaching $100 million, cases increased 10.4%

·                  Pro Forma Adjusted EBITDA of $150.9 million

·                  Reduced debt by $200 million with proceeds from Canada Pension Plan Investment Board (“CPPIB”) investment

Recent Developments:

·                  Entered into new region of Northwestern U.S. through joint venture with Northwest Cancer Clinic, LLC (“NWCC”) in January, 2015

·                  SFRO added two centers, enhancing its coordination of care and ability to leverage resources

·                  Established formal affiliations with the University of Florida (“UF”) and the University of California Los Angeles (“UCLA”)

FORT MYERS, FL, March 18, 2015 — 21st Century Oncology Holdings, Inc. (“21C or the “Company”), the leading global, physician-led provider of integrated cancer care (“ICC”) services, announced today its financial results for the fourth quarter and full year ended December 31, 2014.

Dr. Daniel Dosoretz, Founder and Chief Executive Officer, commented, “We closed 2014 with continued growth in same store freestanding treatments which resulted in our fourth consecutive quarter of year-over-year Pro Forma Adjusted EBITDA margin expansion. We expect these trends of treatment growth and EBITDA margin expansion will continue into 2015. A major Company milestone occurred in September 2014 when we received a $325 million cash equity investment from CPPIB.  During the remainder of the year we used these proceeds to reduce debt by $200 million, bolster liquidity, complete a successful OnCure capital upgrade program, and enter 2015 with a large joint venture in attractive new markets. The resulting deleveraging and liquidity improvement enabled us to maintain our focus during the final months of the year on organic growth, operational improvements, integration execution, improving results in underperforming markets, and expense management.”

Dr. Dosoretz continued, “I am very pleased with our operational results, both domestic and international, during the fourth quarter. Early indications in 2015 show continued organic momentum. We were able to build upon the third quarter and achieve steady same store treatment growth in the fourth quarter of 2.3%, our seventh consecutive quarter of same store growth. Completed case volume increased again this quarter, driven by organic growth and continued significant contributions from our two largest acquisitions, OnCure and SFRO, which closed in October 2013 and February 2014 respectively. Importantly, we believe that they will continue to provide incremental organic growth opportunities via the leveraging of 21C’s clinical leadership, scale, infrastructure, and ICC model. Additionally, in early January we announced a joint venture with Northwest Cancer Clinic, LLC (“NWCC”), expanding our geographical reach into a brand new region in the Northwestern U.S, one of the fastest growing regions in the country. We look forward to updating our stakeholders on additional strategic opportunities currently in the development stage. We remain focused on continued EBITDA growth through 2015 and into 2016 with marketing efforts focused on our key physician communities further complimented by ICC expansion where it is warranted.”

“For the full year, we achieved a 22.5% year-over-year increase in total pro forma revenue and total Pro Forma Adjusted EBITDA of $150.9 million, a year-over-year increase of 27.3%. In 2014, total international cases increased 10.4%, and we expect international revenues to surpass $100 million in 2015. During 2014, we added a net of 123 new physicians. Also during the year we added a net of 17 additional centers, 14 of which are domestic and 3 international. We entered 2015 with the same focus on executing our strategy of organic growth combined with prudently taking advantage of attractive strategic de-leveraging acquisitions and joint ventures in order to continue delivering integrated cancer care at academic quality and create compelling value for our steadily expanding patient population,” added Dr. Dosoretz.

Fourth Quarter 2014 Results

Total pro-forma revenues for the fourth quarter of 2014 were $269.5 million, compared to total pro-forma revenues of $209.2 million in the same quarter of 2013, driven by the Company’s acquisition activity and organic growth.

Domestic same store treatments per day increased 2.3% in the fourth quarter of 2014 while same store freestanding revenues increased 2.0%. The growth was primarily driven by the continued expansion of our physician network and strong growth in our key markets. Domestic same store therapy revenue per treatment decreased 0.3% in the fourth quarter of 2014, primarily due to an increased shift in payor mix to Medicare replacement products.

Total Relative Value Units (RVUs) per day increased by 22.4% in the fourth quarter versus the same period of the prior year due to acquisitions, same store treatment growth and service mix. On a same store basis, RVUs increased 0.2% versus the same period last year. Adjusted earnings before interest, taxes, depreciation, amortization, stock-based compensation and other non-cash and pro forma items (“Pro Forma Adjusted EBITDA”) in the fourth quarter of 2014 was $37.2 million, or 13.8% of total revenues, up 36.6% compared to $27.2 million, or 13.0% of total pro forma revenues, in the fourth quarter of 2013. A reconciliation of net loss attributable to 21C, determined in accordance with generally accepted accounting principles to Pro Forma Adjusted EBITDA and total revenues, determined in accordance with generally accepted accounting principles, to total pro forma revenues for the quarters ended December 31, 2014 and 2013 is included in the attached supplemental financial information.

Income tax expense in the fourth quarter of 2014 was $0.1 million, compared to an income tax benefit of $25.3 million in the fourth quarter of 2013. The net loss for the fourth quarter of 2014 was $22.7 million, compared to a net loss of $14.3 million in the fourth quarter of 2013.

Full Year 2014 Results

Total pro forma revenues for the full year ended December 31, 2014 were $1.0 billion, an increase of 22.5% compared to $845.3 million in revenues for the full year 2013. Full year 2014 pro forma revenues include $8.8 million in revenue contribution from acquisitions, as if the acquisitions had closed on January 1, 2014. The increase in revenue was principally due to increased domestic census, acquisitions, stronger results from joint ventures, and international revenue growth.

Domestic same store treatments per day increased 2.6% for the full year 2014. This was driven by expansion of our ICC model as well as physician and center-level marketing efforts resulting in an increased patient census. Domestic same store therapy revenue per treatment increased 2.5% compared to 2013.

Pro Forma Adjusted EBITDA for the full year 2014 was $150.9 million, or 14.6% of total pro forma revenues, compared to $118.6 million, or 14.0% of total pro forma revenues for the full year 2013.  Pro Forma Adjusted EBITDA margins increased in the current quarter versus the prior year period primarily due to the Company’s focus on expense management. A reconciliation of net loss attributable to 21C, determined in accordance with generally accepted accounting principles to Pro Forma Adjusted EBITDA and total revenues, determined in accordance with generally accepted accounting principles, to total pro forma revenues for the full years ended December 31, 2014 and 2013 is included in the attached supplemental financial information.

Income tax expense for the full year 2014 was $5.2 million, compared to an income tax benefit of $20.4 million in 2013. The net loss for the full year 2014 was $343.2 million, compared to a

net loss of $78.2 million for the full year 2013. The net loss for the full year 2014 included impairment charges of $229.5 million, attributable to revisions of the Company’s financial forecasts largely as a result of reductions in reimbursement and limited capital resources during the second quarter of 2014 that resulted in a write down of goodwill, trade name and an investment in a joint venture to their implied fair values.

Recent Developments

On January 2, 2015, 21C entered into a joint venture with NWCC.  21C acquired an 80% interest in a newly-formed joint venture entity, with NWCC’s current physician leader, Sheila Rege, M.D., holding a 20% equity interest. This joint venture expands 21C’s geographical exposure into a new market in the Northwestern U.S., one of the fastest growing regions in the country, with future expansion opportunities via satellite offices and ICC expansion in the region.

SFRO completed the purchase of a center in Hollywood, Florida, which was previously under a management agreement and another center in downtown West Palm Beach at the Good Samaritan Medical Center.

During the first quarter of 2015 the Company finalized arrangements with two prestigious universities.  21C will in conjunction with UF provide medical and administrative services in the Jacksonville, Florida market and in southern California 21C will partner with UCLA and coordinate care for our mutual patients in convenient community-based locations.

Conference Call

The Company will host a conference call on Thursday, March 19, 2015 at 12:30 p.m. Eastern Time, during which management will discuss its financial results in further detail. The dial-in numbers are (877) 407-9039 for domestic callers and (201) 689-8470 for international callers.  In addition, a telephonic replay of the call will be available until April 3, 2015.  The replay dial-in numbers are (877) 870-5176 for domestic callers and (858) 384-5517 for international callers.  Please use the conference ID number 13604274 to access the replay.

A live webcast and webcast replay of the call will also be available from the Events section on the corporate web site at www.21co.com.

About 21st Century Oncology Holdings, Inc.

21st Century Oncology Holdings, Inc. is the largest global, physician led provider of integrated cancer care services. The Company offers a comprehensive range of cancer treatment services, focused on delivering academic quality, cost-effective patient care in personal and convenient settings. As of December 31, 2014, the Company operated 180 treatment centers, including 144 centers located in 16 U.S. states and 36 centers located in six countries in Latin America.  (Source: 21st Century Oncology Holdings, Inc.)

Forward-Looking Statements

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 Act of 1934, as amended.  Statements preceded by, followed by or that otherwise include the words “believes”, “expects”,

“anticipates”, “intends”, “projects”, “estimates”, “plans”, “may increase”, “forecast” and similar expressions or future or conditional verbs such as “will”, “should”, “would”, “may” and “could” are generally forward-looking in nature and not historical facts. Forward-looking statements are based on management’s current expectations or beliefs about the Company’s future plans, expectations and objectives, including, but not limited to, the Company’s expected financial results and estimates for 2015 and the effects of the CMS’s Final Rule for the 2015 Physician Fee Schedule on its results.  These forward-looking statements are not historical facts and are subject to risks and uncertainties that could cause the actual results to differ materially from those projected in these forward-looking statements including, but not limited to reductions in Medicare reimbursement, healthcare reform, decreases in payments by managed care organizations and other commercial payers and other risk factors that may be described from time to time in the Company’s filings with the Securities and Exchange Commission.  Readers of this release are cautioned not to place undue reliance on forward-looking statements contained herein, which speak only as of the date stated, or if no date is stated, as of the date of this press release. The Company undertakes no obligation to publicly update or revise the forward-looking statements contained herein to reflect changed events or circumstances after the date of this release, unless required by law.

21ST CENTURY ONCOLOGY HOLDINGS, INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

(in thousands, except share amounts)

(unaudited)

21ST CENTURY ONCOLOGY HOLDINGS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

(in thousands)

(unaudited)

21ST CENTURY ONCOLOGY HOLDINGS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

(unaudited)

21ST CENTURY ONCOLOGY HOLDINGS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

(unaudited)

21ST CENTURY ONCOLOGY HOLDINGS, INC.

Supplemental Financial Information (Unaudited)

Reconciliation of Total Pro-forma Revenue and Pro-forma Adjusted EBITDA to Net Loss Attributable

to 21st Century Oncology Holdings, Inc. Shareholder

(1) Pro-forma Adjusted EBITDA is defined as income (loss) before interest expense (net of interest income), income taxes, depreciation and amortization, gain on the sale of an interest in a joint venture, loss on sale leaseback transaction, early extinguishment of debt, fair value adjustment of earn-out liability, fair value adjustment of embedded derivative, impairment loss, foreign currency derivative contract loss (gain), management fees accrued to our sponsor, non-cash expenses including costs relating to stock compensation, amortization of straight-line rent and amortization of capital expenditures relating to repairs and maintenance, non-cash equipment rent, sale-lease back adjustments, acquisition-related costs, other expenses including loss on sale of assets, severance payments related to termination of employee staff reductions, tail premiums on termed physicians, franchise taxes, costs relating to consulting services on Medicare reimbursement, litigation settlements with physicians, costs associated with tradename and rebranding initiatives, expenses associated with idle / closed radiation therapy treatment facilities and pro-forma full period effect of acquisition EBITDA.

(a) Pro-forma amounts related to adjustments to total revenues and Pro-forma Adjusted EBITDA to reflect the full period effect of our acquisitions and Value Added Services contracts completed during 2014 and 2013.  The adjustments reflect the impact to our total revenues and Pro-forma Adjusted EBITDA as if the acquisitions and Value Added Services contracts had occurred at the beginning of the year.

(b) Management fees are fees accrued to our sponsor, Vestar Capital Partners.

(c) Non-cash expenses including costs relating to stock compensation, amortization of straight-line rent, amortization of capital expenditures relating to warranty arrangements amortized to repairs and maintenance and non-cash equipment rent.

(d) Sale-lease back adjustments relates to the adjustment of benefit derived from the classification of operating leases as finance obligations reflecting a reclassification of interest expense and depreciation and amortization expense as rent expense.

(e) Acquisition related costs associated with ASC 805, “Business Combinations”, including professional fees, corporate development, integration and due diligence costs relating to the acquisition of medical practices.

(f) Other expenses include loss on sale of assets, severance payments related to termination of employee staff reductions, tail premiums paid on terminated physicians, franchise taxes and costs relating to consulting services on Medicare reimbursement.

(g) Litigation settlement relates to costs associated with the termination of physicians and loss contingency reserves related to the Medicare diagnostic testing matter.

(h) Expenses related to the costs associated with the Company’s tradename and rebranding initiatives.

(i) Expenses associated with idle / closed radiation therapy treatment facilities.

(j) Expenses associated with negotiating with note-holders, recapitalization support agreement and legal and consulting fees associated with management of liquidity.

We believe the Pro-forma Adjusted EBITDA provides useful information about our financial performance to investors, lenders, financial analysts and rating agencies since these groups have historically used EBITDA-related measures in the healthcare industry, along with other measures, to estimate the value of a company, to make informed investment decisions, to evaluate a company’s leverage capacity and its ability to meet its debt service requirements.  Pro-forma Adjusted EBITDA eliminates the uneven effect of non-cash depreciation of tangibles assets and amortization of intangible assets, much of which results from acquisitions accounted for under the purchase method of accounting.  Pro-forma Adjusted EBITDA is also used by us to measure individual performance for incentive compensation purposes and as an analytical indicator for purposes of allocating resources to our operating business and assessing their performance, both internally and relative to our peers, as well as to evaluate the performance of our operating management teams, and for purposes in the calculation of debt covenants and related disclosures.

Pro-forma Adjusted EBITDA is not intended as a substitute for net income (loss) attributable to 21st Century Oncology Holdings, Inc. shareholder, operating cash flows or other cash flow data determined in accordance with accounting principles generally accepted in the United States. Due to varying methods of calculation, Pro-forma Adjusted EBITDA as presented may not be comparable to similarly titled measures of other companies.

21ST CENTURY ONCOLOGY HOLDINGS, INC.

KEY OPERATING STATISTICS

(unaudited)

*       Total cases completed represents a count of patients that have completed their course of treatment. Total case counts are based on legacy and acquired clinical systems.