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Preventing Fatal Second Malignancies from IMRT

by: R L McLaurin Jr MD MBA

IMRT:   Intensity Modulated Radiation Therapy is a relatively recent innovation in the history of Radiation Oncology.  It employs sophisticated computer treatment planning software and hardware to focus the damaging effects of radiation on the malignant tumor while reducing the dose to nearby normal tissues.  It is a major technologic advance over the prior state-of-the-art technique of 3D Conformal Radiation Therapy (3D-CRT).

Years of accumulated data fail to show that IMRT produces any improvement in survival compared to 3D-CRT.  Nonetheless, Medicare pays approximately $45,000 per patient for IMRT vs. $12,000 for 3D-CRT.  The evidence does demonstrate that IMRT provides a small reduction in proctitis, but that advantage is more than offset by a dramatic increase in the risk of fatal second malignancies.

The Institute for Clinical and Economic Review (ICER) conducted a thorough analysis in 2007 comparing IMRT to 3D-CRT for the treatment of localized prostate cancer.  Their findings confirm that IMRT produces no survival benefit.  ICER concluded that the clinical effectiveness of IMRT is not superior to the established standard, and the comparative value of IMRT is low.

 SMART:  Stereotactic Multiple Arc Radiation Therapy is an incremental improvement over conventional 3D-CRT.  It integrates the inherent advantages of “Arc” treatment techniques.  Arc treatment delivers radiation while the radiation source is rotating around the patient.  The advantage of this technique derives from the fact that virtually all tumors have rounded surfaces.

There has never been a square tumor, or a hexagonal one or an octagonal one.  The common 4 or 6 or 8-field plans using a finite number of static portals cannot provide as good a fit to the tumor, because the Arc technique enables us to “bend” the isodose curves to conform more precisely to the target contour.  Simple geometry dictates that the greatest area that can be contained in a given perimeter is a circle.  All of the “extra” area contained in other shapes exposes additional normal tissue to unnecessary radiation.

SMART exclusively employs 6 MV beams, partly because of the risks inherent in high-energy beams.  High-energy beams produce increased radiation scatter and neutron contamination.  These problems are exacerbated by IMRT, and are the root cause of the enhanced risk of fatal second malignancies.

Research has also shown that 6 MV beams produce the optimal treatment plans.  A recent study exploring the effect of beam energy on treatment plan quality in the modern era of sophisticated treatment planning demonstrates that, “for plans with comparable target coverage, critical structure sparing is best achieved with 6 MV beams.”

Prostate Cancer: Not all malignancies are created equal.  Cancer is a disease characterized by a wide spectrum of virulence, and the control rates differ dramatically among malignancies originating from different organ sites.  The National Cancer Institute regularly assembles 5-year relative survival tables, which tabulate the actual survival of patients diagnosed with cancers from various sites, and compares them to the expected actuarial survival of an age-matched cohort of patients who have never had cancer.  These tables demonstrate that the control rate for lung cancer remains dismal at 14%, while the overall 5-year relative survival rate for prostate cancer is 100%. 

 The 100% 5-year relative survival for patients diagnosed with prostate cancer is partly due to improved early detection.  Since the widespread use of the PSA test, there has been a profound “stage shift,” such that the vast majority of prostate cancer cases diagnosed in America today are found in the earliest stage, when the disease is still confined within the prostate gland.  Treatment of organ-confined prostate cancer, whether by surgery or radiation, is highly successful.  For patients diagnosed with localized prostate cancer, cures are the rule rather than the exception.

In order to be absolutely certain that the 5-year relative survival rates are reliable, the National Cancer Institute analyzes only results of patients who have been followed for at least 5 years.  Therefore, the survival tables published in 2007, which demonstrate the 100% 5-yr relative survival rate, reflect the results for patients treated before 2002.  The timeframe is important because 2002 was the year that Medicare began to reimburse for IMRT, which marked only the beginning of the widespread adoption of IMRT.  The excellent survival rates were established prior to the generally availability of IMRT.

Destructive Technology: Despite the paucity of data to support the use of the newer, more expensive modality, the extremely high level of reimbursement has driven virtually every Cancer Center in the State of North Carolina to undertake a wholesale conversion to IMRT.  It has been marketed very aggressively by those who have paid to obtain the technology, some claiming that IMRT must be considered the sole standard of care.

Most troubling about these claims is that they intentionally ignore the fact that IMRT produces a dramatic increase in the risk of fatal second malignancies.  Kry and Followill, radiation physicists from M D Anderson Cancer Center, demonstrated that the risk of fatal second malignancies from IMRT is in the range of 3–5% (see table above).

Followill earlier demonstrated an expected rate of 0.3% for conventional radiation treatment using 6 MV beams.  Thus, IMRT produces a 10 to 17 fold increase in the rate of fatal second malignancies compared to treatment strategies based on conventional radiation with 6 MV beams.

Put another way, the use of IMRT to treat a prostate cancer patient introduces approximately 3-5% risk of additional deaths from second cancers caused solely by the choice of treatment modality.

Since IMRT provides no survival benefit, the added risk of fatal second malignancies would actually decrease the likelihood of survival.  The decreased survival is not yet evident because there is a long lag time from the exposure to high levels of radiation and the subsequent manifestation of second fatal malignancies.  The risk estimates are based upon rigorous scientific measurements, and calculated from well-established coefficients provided by the Nuclear Regulatory Commission (NRC).  These coefficients are derived from data on previous radiation exposure events such as Hiroshima.

Why would anyone pay 4 times as much for the privilege of being exposed to such risk?

Franklin County Cancer Center is the only radiation treatment facility in this part of the state that has not succumbed to the temptation to over-charge patients by using IMRT.  My refusal to install the IMRT technology was made purely on principle.  The “McLaurin Arch” has been commercially available since the mid-1990’s and has been marketed as “IMRT-enabling technology.”  It is among the tools other Cancer Centers around the country, and around the world, use to make IMRT possible.

I could have easily installed the remaining IMRT hardware and software, and would have recaptured my costs in the treatment of the first few prostate cancer patients.  I have chosen not to do so because of ethical reservations regarding both the costs and the risks of the technology.

The recent universal conversion to IMRT by all the other Cancer Centers in the region means that every patient with early stage prostate cancer who get sent out of Franklin County for radiation treatment is now getting charged approximately 4 times as much – to achieve the same short-term results – while exposing him to an unacceptable level of potentially fatal long-term consequences.

If the patient happens to be an employee of Franklin County, though the individual risks paying the ultimate price, it is the county taxpayer who pays the extra cost, both for the current treatment and the cost of the later consequences.

Conclusion:  The exorbitant financial costs and the extremely high risk of fatal second malignancies associated with IMRT far outweigh the modest reduction in proctitis it provides.  The increased risk of fatal second malignancies from IMRT may be as high as 5%.  The best way to prevent unnecessary deaths from IMRT is avoid its use in the first place.