One example of how Clinical Cancer Registry level data can review practice variation - assessment of the variations in use of hypofractionation in NSW 2007-2012 for early, node-negative breast cancer.
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We examined the possible utility of using Cancer Institute NSW Clinical Cancer Registry data by examining one contentious issue in radiation oncology as an example. Increasing evidence has been published about the safety and efficacy of hypofractionated radiotherapy, in comparison with standard fractionation, in early, node-negative breast cancer.
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One example of how Clinical Cancer Registry level data can review practice variation - assessment of the variations in use of hypofractionation in NSW 2007-2012 for early, node-negative breast cancer.
- 2. The use of NSWCI data to review clinical variations – Early Breast Cancer Hypofractionation: A Case Study Delaney G., Gandhidasan, S., Walton R., Terlich F., Baker D., Currow D. NSW Cancer Institute and SWSLHD
- 3. Aims of this presentation • Introduce the concept of clinical variation assessment using NSWCCR data • Explore the variations of practice in hypofractionation for early breast cancer XRT to assess what factors impact adoption of new treatments • Hypofractionation in breast tangents – Controversial – Likely to be variation – Evidence evolution over time
- 4. NSW Cancer Registry • Combined data from the mandated Central registry and clinical data from most LHDs (since 2005) • 388 000 cases within the registry with complete data – Lacking private hospital data (coming) – Lacking data from some rural LHDs (coming) – Long-term plans for an entire data set
- 5. Breast Cancer Hypofractionation • Hypofractionation is giving XRT in a shorter number of fractions e.g. 16 versus conventional 25 • 5 RCTs with long-term follow-up have shown equivalence to standard fractionation for early breast cancer (local control and survival) • Possible long-term toxicity concerns relate to high fraction size (2.6-2.7 Gy versus standard 1.8-2) • Longer term case control studies have shown no additional toxicity
- 6. Tangent XRT Hypofractionation Author Tmt years # regimen n Median (range) F/U (yrs) Year of publication Baillet et al. 1982-1984 23/4 230 5.5 1990 Whelan et al. 1993-1996 42.5/16 1234 12 (>10) 2002/2010 Yarnold, Owen et al. 1986-1998 39/13 42.9/13 1410 9.7 (7-18.4) 2005/2006 Yarnold et al. (START B) 1999-2001 40/15 2215 6.0 (<8) 2008 Yarnold et al. (START A) 1998-2002 41.6/13 39Gy/13 2236 5.1 (<8) 2008 Lalani et al. 1994-2003 Various (non RCT) for DCIS 1609 9.2 2014
- 10. ASTRO and Australian guidelines Recommend breast hypofractionation but perhaps insufficient evidence in some sub-groups • Large breast • Chemotherapy • Young women • Node XRT http://guidelines.canceraustralia.gov.au/guidelines/guideline_12.pdf
- 11. So what should the benchmark be? ASTRO/Australian guidelines
- 12. So what should the benchmark be? • All patients (believers) = 100% – Long term follow up available – Adoption by some other groups as standard e.g. some parts of Canada – Leads to greater resource efficiency • Selected patients (believe where evidence strong) = 40% • No patients (non-believers) = 0% – Old way is tried and tested – Long-term toxicity still not long enough especially for rarer toxicities such as cardiac risk
- 13. Methodology • All T1-2N0M0 treated with tangent XRT during the XRT study period 2008- 2012 in public XRT dept. • Analysis of dose/fraction (hypo# defined as >2.4Gy/f) against : – age, – laterality, – residence distance from department, – year of tmt, – department treated – clinician NO surrogate marker for breast size available
- 14. RESULTS • 10572 patients with T1-2N0M0 • 6066 (63%) treated with XRT in a public facility – 3947 (65%) received standard – 2119 (35%) received hypo Estimate z value P value Age at diagnosis (10 years) OR = 2.10 20.756 P<0.001 Laterality (right vs left) OR = 1.27 3.285 P=0.001 Distance (100km) OR = 1.12 3.105 P=0.002 Year OR = 1.15 4.858 P<0.001 AMO σ σ = 1.09 Facility σ σ = 1.39 The greatest predictor for variability was clinician
- 15. 50 60 70 Median age (yrs) 6 8 9 10 16 22 26 28 32 43 69 71 72 92 35 94 92 91 90 84 78 74 72 68 57 31 29 28 8 65 0% 100% Facility 14 (n=118) Facility 13 (n=260) Facility 12 (n=368) Facility 11 (n=520) Facility 10 (n=670) Facility 9 (n=571) Facility 8 (n=438) Facility 7 (n=826) Facility 6 (n=526) Facility 5 (n=244) Facility 4 (n=98) Facility 3 (n=280) Facility 2 (n=888) Facility 1 (n=259) Total (n=6066) Treatment regimen received (%) Hypofractionation Standard
- 16. 6 10 5 20 18 27 31 38 39 48 53 65 82 94 90 95 80 82 73 69 62 61 52 47 35 18 0% 100% < 30 (n=18) 30-34 (n=68) 35-39 (n=133) 40-44 (n=322) 45-49 (n=581) 50-54 (n=842) 55-59 (n=854) 60-64 (n=1079) 65-69 (n=1030) 70-74 (n=521) 75-79 (n=353) 80-84 (n=195) 85+ (n=68) Treatment regimen received (%) Agegroupattreatment Hypofractionation Standard
- 17. 25 34 36 38 40 0 100 2008 2009 2010 2011 2012 Hypofractionationreceived(%) Year of treatment
- 18. 14 7 10 7 17 30 27 29 34 45 75 71 74 88 36 4 4 9 10 15 16 25 28 31 42 67 68 71 97 34 0 100 Facility 14 (n=260) Facility 13 (n=118) Facility 12 (n=518) Facility 11 (n=368) Facility 10 (n=670) Facility 9 (n=571) Facility 8 (n=437) Facility 7 (n=826) Facility 6 (n=521) Facility 5 (n=244) Facility 4 (n=280) Facility 3 (n=98) Facility 2 (n=884) Facility 1 (n=259) Total (n=6054) Hypofractionation received (%) Left Right
- 19. Summary findings • Difference in use of hypofractionation • Variation causes are multi-factorial (facility, AMO, age, laterality, distance) • Clearly the area remains controversial in NSW • Identifying some factors might help understand motivation and set future research direction • Raises issues about whether variation is appropriate or not
- 20. Is follow-up long enough?
- 21. Other regions AUTHOR REGION STUDY PERIOD HF RATE PREDICTORS Dayes et al. Ontario, Canada 1999-2001 100% Substantially higher than a similar US cohort Jagsi et al. Michigan, US 2011-2013 31% older age, smaller body habitus, no chemo Jagsi et al., SEER, US 2004-2010 23% (2009- 2010) Older age, smaller T, increased comorbidity, higher education, region, year Wang et al., NCDB, US 2004-2011 23% (2011) Year, travel distance, academic facility, high median income, smaller T, lower grade Bekelman et al. 14 US centers 2008-2012 21% (2012) Year, older age, IMRT use, type of facility THIS STUDY NSW 2008-2012 35% (2008- 2012) Facility, AMO, year, laterality, older age, travel distance
- 22. Where to from here? • Registry data – Consider other variations in treatment e.g. SNB, WLE, post- mastectomy XRT, chemotherapy • Hypofractionation - Feed data back to departments - Update data and include private departments - Focus groups, debate the evidence - Review literature - Consensus recommendations - Ideal to link these data to outcome data (e.g. long-term IHD data) - Feedback quality loop - Increased access to techniques that minimise heart dose might help
- 23. Thank you
Editor's Notes
- Thankyou to the organizers for the invitation to present this paper.
- The aims of this paper are to highlight the data available in the Clinical Cancer Registry and how it might be used to assess clinical practice variation. In this example, we examine the patterns of hypofractionation in early breast cancer radiotherapy. The reason why we chose this topic is that it is controversial, there is likely to be wide variation, the evidence has evolved throughout the study period so we thought it might be interesting to see how evidence led to, or did not lead to, change.
- The NSW Clinical Cancer Registry is an amalgamation of the old Central, legally-mandated registry system established in 1972 along with the Clinical Cancer registries that were commenced in 6 lead LHDs in 2005 that collect additional data on treatment. Currently there are 388 000 cases that have full data including treatment, although currently there are several limitations in completeness that are currently being worked on, including access to private hospital data and some regions of the state. The long-term plans are to fill these gaps.
- Hypofractionation is defined as giving radiotherapy in a shorter number of treatments than the conventional 25 treatments usually usually in about 13-15 treatments at a higher dose per fraction or per treatment. 5 randomised controlled trials have identified that with medium term to long-term follow up that hypofractionation regimens are equally well-tolerated and have similar local control rates. There was the potential that we might have seen greater long term toxicity with the bigger fraction sizes. However, that has not been the case to date.
- The 5 trials are listed here in black. Note that these studies have large patient numbers and have been published 6-10 years ago, and some have follow up that is beyond 10 years. The study in orange is a non-randomised case control series in DCIS that also has long follow up and shows no difference in long term toxicity.
- In 2010, an entire edition of the Breast Journal was devoted to hypofractionation in breast, with Canadian experts arguing that hypofractionation should become routine practice.
- As did experts from the NICE guidelines.
- The ASTRO group, and the Australian group, of which I was a member (with the hyperlink below), were a little more cautious…
- ..in that they said that hypofractionation could be considered reasonable in many patients although several sub-groups were perhaps insufficiently represented in these trials to make a blanket rule. These included patients with large breasts, those having had chemotherapy, women less than 50, and when the nodes are to be treated. However, it was reasonable to even consider these patients.
- Our group have also created a decision tree to estimate what proportion of patients fit into the “well-studied” group of the ASTRO and Australian guidelines, so if we were to exclude all patients that are <50, or have chemotherapy or have a larger breast then we estimate that about 40% of women still fall within the well-studied group where even the conservative Australian and ASTRO guidelines would recommend hypofraction. Only 5 of the 14 radiation oncology departments have a rate higher than 40%.
- So what should the benchmark be? There might be 3 groups of clinicians. Those that are largely believers, treating a high proportion of patients with hypofractionation. The middle group of tailors, who might tailor treatment to selected patients where the evidence is most representative and the non-believers that despite what has been published remain concerned, either by resisting change as the old way remains a good treatment or they have some ongoing doubts about longer-term toxicity.
- In this study we studied the public radiotherapy fractionation regimens of all early, node negative breast cancer patients within the registry who received XRT between 2008 and 2012. Hypofractionation was defined as treatment with a treatment fraction greater than 2.4Gy. We assessed the rate of hypofractionation against various factors including patient age, the laterality of the treatment, the distance from home to treatment, the year treated and the department where treated. Breast size was unable to be assessed.
- 10572 patients with early breast cancer were identified, 6066 of whom received radiotherapy during this period representing 63% of all early breast cancer patients. Of those patients 35% of patients received hypofractionated radiotherapy. Factors that were significant predictors for receiving hypofractionation were older age, laterality, further distance from treatment, later year of treatment, treating clinician and treating facility. The factor that most affected variability was the treating clinician.
- The range of hypofractionation by department was 92% to 6%, with stepwise increases across the 14 facilities. You will note on the right that median age where hypofractionation was used was higher in all centres, with some centres seeming to more preferentially treat older patients with hypofractionation than other departments.
- There was a variation according to age across the cohort, with 82% of women older than 85 receiving hypofractionation, compared with <20% of women less than 50.
- There was a mild increase in the use of hypofractionation with increasing year although I remind you that the guidelines and the majority of the papers were published by the end of 2010 suggesting little publication impact on practice change.
- Some departments also had a small preference for treating right sided breasts with hypofractionation compared with the left breast. This is presumably due to concerns some clinicians might have about heart dose for the left breast treatments when using high dose per fraction.
- So our main findings were that there is significant variation in hypofraction use in public radiotherapy facilities across the state. Variations appear to be multi-factorial. By identifying and attempting to understand this variation then one might be able to develops strategies to reduce this variation over time. It also raises issues whether treatment variations like this are appropriate or not.
- So maybe there remains doubt. For example, this Norwegian study examined retrospectively the IHD death rate for patients receiving hypofractionation versus standard. Now this is a different cohort to early breast in the nodal treatments were also given. However, the point I wanted to highlight here is that the curves only start to separate at 13 years follow up so maybe there is a reasonable concern harboured by the radiation oncologists, so I am not necessarily standing up here saying that I know what the answer should be.
- Apart from the Ontarians who appear to have adopted hypofractionation uniformly, when compared with North American centres, our results are comparable. We are the first to identify laterality as being a factor. Most of the other factors have been shown by others to also predict for hypofractionation use.
- So, hopefully I have provided you with some interesting data to at least start the debate about clinical variation and how we might use registry in studying other clinical variations. With respect to hypofractionation we plan to feed these data back to the departments so they know where they sit compared to other departments to at least allow them the opportunity to review their practice. In order to elicit change, if that is thought appropriate, then this will require updating of the data and including the private departments, developing focus groups and reviewing the evidence and guidelines to decide what is reasonable and then to continually feed the data back. Ideally it will be good to link the radiotherapy data to long-term cardiac data to then see whether concerns regarding toxicity are valid or not. In addition, now that there are emerging radiotherapy techniques that reduce heart dose such as breath-hold, perhaps these arguments are less valid now. Thank you for your attention.
- Thank you