Advances and Challenges in Radiation Protection of Patients Modern Radiotherapy. Risk Acceptability

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1 Advances and Challenges in Radiation Protection of Patients Modern Radiotherapy Risk Acceptability Versailles, France December 2-4, 2009 Fred A. Mettler Jr. M.,D., M.P.H. New Mexico Federal Regional Medical Center Albuquerque, New Mexico, USA

2 Radiation Protection in Medicine ICRP 105 says.. Justification.. Use of radiation in medicine (level1) of a practice/procedure (level 2) for an individual (level 3) Benefit should exceed risk Optimization of the relationship between tumor control and complications..but there is little guidance on how risk/benefit balance is to be done in medicine or who actually does it

3 Risk Is risk really quantifiable? While many dangers are quantifiable. judgments, values and culture affect acceptability of risk A basic difficulty is that those should or will participate in the risk decision have divergent perspectives Radiation risk and acceptability cannot be dealt with alone. They occur in a world with many other factors

4 Quantitative risk assessment (QRA): Can we do it for cancer therapy? What can go wrong with our system? What is the likelihood of that happening under the current plan? If it does happen what are the consequences? i.e. what is the damage?

5 Can we find an extreme example of radiation and other risks.. to look at how risk acceptability is done?

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8 The radiation protection philosophy and risk acceptability views of an astronaut Ellen Baker, NASA As astronauts our mission risks are high but that does not mean that we should also accept high levels of radiation risk We still do not understand the full range of radiation risks Therefore we rely on you to provide us with the latest information and provide us with the most up-to-date techniques to reduce or minimize radiation risks

9 What is the universe of risk the patient is faced with? A tour of risk through the patients eyes Prostate cancer as an example most common cancer in men

10 Risk acceptance in radiotherapy Who accepts the risk???? The patient.. Isn t that obvious??

11 Can we really expect any normal 70-year old figure out whether to accept the risks and uncertainties that are associated with prostate cancer? Occult tumors Clinical staging PSA screening Cryosurgery Biopsy PSA velocity Impotence Gleason score Watchful waiting Biochemical recurrence IMRT Bone scan/ct/mri Brachytherapy Hormone therapy Radical prostatectomy Survival rate Conformal radiotherapy Robotic surgery

12 The risk/decision pathways for the prostate cancer patient PSA Screen no yes RPP PSA < 4 <4 but rising >4 no Biopsy yes Gleason 6 or less 7 8,9 Staging Clinical no Bone scan/ct/mri yes Robotic External Brachytherapy Both Surgery Radiation? negative equivocal positive no Hormone yes

13 PSA Screen no yes RPP Biopsy yes Gleason 7 8,9 Robotic Risk of anywhere from 15-30% Surgery of being wrong about whether he has cancer at all and it may not make External much difference in outcome Radiation Brachytherapy? Both Percent of patients with PSA < 4 with cancer ~15% Percent of patients with PSA > 4 without cancer ~ 65-75% no PSA screening doubles the 6 incidence or less of diagnosis does not change death rate (NEJM 360: ,2009) negative no Bone scan/ct/mri yes equivocal positive Staging Clinical yes Hormone no

14 Can PSA or Gleason score determine bone metastases or disease extent? PSA < >50 1.7% 5.9% 11.5% 53.3% Gleason score A score of 7 or greater has a 58% accuracy regarding disease confined to the prostate this criteria has a 42% chance of being wrong

15 What are results of bone scans? Staging 9% positive 9% equivocal 82% negative Or ~10% of the time we say we don t know whether you have metastatic disease or which therapy is appropriate Followup - 18% positive - 9% equivocal -73% negative

16 How accurate are the bones scan interpretations?

17 NaF-18 PET/CT bone scan

18 NaF-18 PET/CT bone scan

19 More NaF-18 scans read as equivocal but 8/8 biopsies were negative for malignancy..

20 How accurate is the clinical staging by the physician? Subsequent surgery has shown that about 50% of the time, clinical staging underestimates the spread of disease Or a risk of 50% error if you only rely on your doctors physical examination

21 Which therapy should I have?

22 Risk Perception and communication What you said was not necessarily what you meant and What you said was not necessarily what he heard

23 How the same risk data presented differently affects choice Mortality rate Survival rate Surgery Radiation Surgery Radiation Treatment 10% 0% 90% 100% After 1 yr 32% 23% 68% 77% After 5 yr 66% 78% 34% 22% % choosing RT 44% 18% McNeil NEJM ,1982 assumed lung cancer

24 Where is the data on which therapies work best? I will ask Dr. Google...

25 da Vinci robotic therapy ad

26 Surgery has a better cure rate than brachytherapy

27 Brachytherapy possibly combined with external is almost as good as surgery and with fewer complications

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29 OK, I ve confused myself enough on all the other issues and I have now decided to do radiation therapy what are my risks from that??

30 Prostate radiotherapy complications External Urinary grade 3 or more 8% GI toxicity grade 3 or more 3-4% Brachytherapy 21% nocturia 12% need β blockers 8-9% erectile dysfunction 6% incontinence 5% rectal injury 3-8% catheter dependent or need surgery

31 What is the radiotherapy accident risk? In the U.S. annually 197,000 patients get external beam radiotherapy for prostate cancer and ~50,000 get brachytherapy

32 92 of 116 cases under-treated

33 What is the second cancer risk from prostate radiotherapy? Depending on what you read Pick a number between 0 and 25%

34 2007 Literature review from mid 1980 to after age adjustment no clear increase was detectable 0% risk

35 2008 The age adjusted rate of SPC for external beam was 2.45/100,000 The hazard ratio for SPC was 1.26 for external beam compared to no radiotherapy (26% increase) No significant differences were seen in the incidence of radiation-induced second primary cancers between the radiation therapy groups

36 2007 approximately one in 70 patients undergoing radiation and surviving more than 10 years will develop secondary cancer.or 1.4% not necessarily due to radiation

37 2009 external Overall incidence of SPC was 8.4% 1747 cases / 100,000 for surgery and radiotherapy 1581 cases/ 100,000 for surgery only..an excess of 374 cases/100,000 was seen in the external radiotherapy group compared to surgery or 0.4% excess risk

38 Even what risk is accepted by the patient does not occur in a void Family Age Quality of life Co-morbidities Financial Availability Trust in physician

39 A large part of risk acceptance is not really done by the patient at all But by Patient Family Physician Institution Manufacturers Regulators Society

40 What I would ask Has the machine been fixed lately? What are the qualifications of the staff? Are there recent changes in staff? What are the data on cure and complication nationally compared to this hospital? During my treatment, how do you check what dose I am getting or have gotten? How long has this particular machine and protocol been used?

41 My conclusions The patient does not really understand all the risks in a complex situation and therefore cannot fully accept the risk The techniques and treatments change rapidly and risk is often not well defined so physicians cannot fully explain the risks Many risks are determined (accepted) by manufacturers, advisory and regulatory bodies who have made decisions

42 My conclusions Radiation risks are not the major issue faced by the patient. There are many other larger risks and unknowns the patient must deal with. Radiation risks are essentially controlled (accepted) by persons other than the patient Risk acceptance largely depends on the trust in the institutions presenting the expert rating and by the previous success and failures of those institutions. (Short 1984)

43 Philosophy of protection (astronaut) patient As (astronauts) patients our (mission) risks are high but that does not mean that we should also accept high levels of radiation risk We still do not understand the full range of radiation risks Therefore we rely on you to provide us with the latest information and provide us with the most up-to-date techniques to reduce or minimize radiation risks

44 Does it work that way all the time??

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50 Thank you