Population Analysis of SABR/SRS for the Treatment of Metastatic Cancer in a Jurisdiction of 15 Million People

PURPOSE/OBJECTIVE(S)

Stereotactic Ablative Radiotherapy (SABR) or Stereotactic Radiosurgery (SRS) for oligometastatic cancer or oligoprogression of metastatic cancer is supported by an expanding body of evidence in the literature. The degree of uptake of these techniques, supplanting traditional and potentially less resource-intensive techniques in this patient population, would be of interest to clinicians and administrators alike.

MATERIALS/METHODS

A review of provincial date for Ontario, Canada (population ∼ 15 million) was performed to quantify the use of SABR/SRS to metastases either in the brain or elsewhere in the body. Data was obtained from a new (April 2022) activity-based hospital funding model, responsible for ALL radiation treatment remuneration at all facilities across the province (i.e., single payer system). Funding is triggered when a patient is treated as per 1 or more of the ∼270 provincial radiation protocols, defined as a "protocol instance". Protocols were developed by clinicians across Ontario according to a consensus-based iterative process, considering provincial, national and international guidelines and/or evidence-based practice. Prerequisite information for remuneration included (but was not limited to): patient demographics, identification of whether a primary tumor or metastasis(es) was treated, protocol, radiation technique, dose/fractionation, and encounter dates. Submission of data was performed by the 17 hospitals who provide radiation services and logic checked centrally by the provincial cancer agency following submission. Validation of data is performed by ongoing iterative processes.

RESULTS

From April 1 to November 30, 2022, a total of 31,916 radiation protocol instances were funded for 27,298 patients. Of these, 4,156 (13%) were SABR/SRS protocols. When only treatment to metastases were considered, the total number of SABR/SRS protocol instances was 3,024 (9.5% of total) and 29.4% of the total number of protocol instances delivered to metastases (10,271). The 29.4% was split further as 1567 protocol instances (15.3%) to brain metastases and 1457 protocol instances elsewhere in the body, most often to lung (3.9%), spine (3.4%), non-spine bone (2.2%) and liver (1.7%), with a further 2.9% to unspecified extra-cranial metastases. Data for all 17 Ontario treatment facilities revealed a range of SABR/SRS usage for metastases from 1.8 to 59.8% (median 23.2%, IQ range 16.9%).

CONCLUSION

On review of recently submitted data, nearly 1/3 of all radiation treatments to metastases in Ontario are delivered using a SABR/SRS technique. There is wide regional variation in the use of these techniques. Reasons for this variation require further investigation.

Locoregional management of in-transit metastasis in melanoma: an Ontario Health (Cancer Care Ontario) clinical practice guideline

Objective

The purpose of this guideline is to provide guidance on appropriate management of satellite and in-transit metastasis (itm) from melanoma.

Methods

The guideline was developed by the Program in Evidence-Based Care (pebc) of Ontario Health (Cancer Care Ontario) and the Melanoma Disease Site Group. Recommendations were drafted by a Working Group based on a systematic review of publications in the medline and embase databases. The document underwent patient- and caregiver-specific consultation and was circulated to the Melanoma Disease Site Group and the pebc Report Approval Panel for internal review; the revised document underwent external review.

Recommendations

"Minimal itm" is defined as lesions in a location with limited spread (generally 1-4 lesions); the lesions are generally superficial, often clustered together, and surgically resectable. "Moderate itm" is defined as more than 5 lesions covering a wider area, or the rapid development (within weeks) of new in-transit lesions. "Maximal itm" is defined as large-volume disease with multiple (>15-20) 2-3 cm nodules or subcutaneous or deeper lesions over a wide area.■ In patients presenting with minimal itm, complete surgical excision with negative pathologic margins is recommended. In addition to complete surgical resection, adjuvant treatment may be considered.■ In patients presenting with moderate unresectable itm, consider using this approach for localized treatment: intralesional interleukin 2 or talimogene laherparepvec as 1st choice, topical diphenylcyclopropenone as 2nd choice, or radiation therapy as 3rd choice. Evidence is insufficient to recommend intralesional bacille Calmette- Guérin or CO2 laser ablation outside of a research setting.■ In patients presenting with maximal itm confined to an extremity, isolated limb perfusion, isolated limb infusion, or systemic therapy may be considered. In extremely select cases, amputation could be considered as a final option in patients without systemic disease after discussion at a multidisciplinary case conference.■ In cases in which local, regional, or surgical treatments for itm might be ineffective or unable to be performed, or if a patient has systemic metastases at the same time, systemic therapy may be considered.

OCTANE (Ontario-wide Cancer Targeted Nucleic Acid Evaluation): a platform for intraprovincial, national, and international clinical data-sharing

Cancer is a genetic disease resulting from germline or somatic genetic aberrations. Rapid progress in the field of genomics in recent years is allowing for increased characterization and understanding of the various forms of the disease. The Ontario-wide Cancer Targeted Nucleic Acid Evaluation (octane) clinical trial, open at cancer centres across Ontario, aims to increase access to genomic sequencing of tumours and to facilitate the collection of clinical data related to enrolled patients and their clinical outcomes. The study is designed to assess the clinical utility of next-generation sequencing (ngs) in cancer patient care, including enhancement of treatment options available to patients. A core aim of the study is to encourage collaboration between cancer hospitals within Ontario while also increasing international collaboration in terms of sharing the newly generated data. The single-payer provincial health care system in Ontario provides a unique opportunity to develop a province-wide registry of ngs testing and a repository of genomically characterized, clinically annotated samples. It also provides an important opportunity to use province-wide real-world data to evaluate outcomes and the cost of ngs for patients with advanced cancer. The octane study is attempting to translate knowledge to help deliver precision oncology in a Canadian environment. In this article, we discuss the background to the study and its implementation, current status, and future directions.

Patient indications for Mohs micrographic surgery: a clinical practice guideline

Objective

The purpose of the present work was to develop evidence-based indications for Mohs micrographic surgery in patients with a diagnosis of skin cancer.

Methods

The guideline was developed by Cancer Care Ontario's Program in Evidence-Based Care, together with the Melanoma Disease Site Group and the Surgical Oncology Program, through a systematic review of relevant literature, patient- and caregiver-specific consultation, and internal and external reviews.

Recommendation 1

Given a lack of high-quality, comparative evidence, surgery (with postoperative or intraoperative margin assessment) or radiation (for those who are ineligible for surgery) should remain the standard of care for patients with skin cancer.

Recommendation 2

Mohs micrographic surgery is recommended for patients with histologically confirmed recurrent basal cell carcinoma of the face and is appropriate for primary basal cell carcinomas of the face that are larger than 1 cm, have aggressive histology, or are located on the H zone of the face.

Recommendation 3

Mohs micrographic surgery should be performed by physicians who have completed a degree in medicine or equivalent, including a Royal College of Physicians and Surgeons of Canada Specialist Certificate or equivalent, and have received advanced training in Mohs micrographic surgery.

A Population-based Study of Survival Impact of New Targeted and Immune-based Therapies for Metastatic or Unresectable Melanoma

AIMS

New targeted drugs and immune therapies reported since 2010 for metastatic or unresectable melanoma (MM) have shown improved survival in randomised trials. We studied the uptake of these new drugs and their impact on population-based survival.

MATERIALS AND METHODS

This was a retrospective, population-based cohort study of all patients treated for MM in Ontario 2007-2015. Provincial administrative sources covering the whole population identified palliative systemic therapy, radiotherapy and metastasis surgery. Temporal trends in utilisation and survival were investigated, as was survival of treatments predefined as 'new drugs' (BRAF or MEK inhibitors, anti-CTLA4 and anti-PD-1 antibodies).

RESULTS

We identified 2793 treated MM patients. First treatment was systemic therapy (46%), radiotherapy (41%) and metastasis surgery (14%). Systemic treatment increased from 53% of patients (2007) to 75% (2015). New drug treatments increased from <6% of known first-line regimens in 2007 to 82% in 2015. One and 2 year overall survival was 28% and 15%, respectively, for all MM 2007-2009, rising to 46% and 35% for 2014-2015 (adjusted hazard ratio 0.56, 95% confidence interval 0.49-0.63, P < 0.0001). Survival gains were observed primarily among those cases initially treated with systemic therapy, which became dominated by the use of new drugs over the study period (2 year overall survival 16% 2007-2009 versus 44% 2014-2015; adjusted hazard ratio 0.46, 95% confidence interval 0.38-0.56, P < 0.0001).

CONCLUSIONS

Utilisation of new targeted drugs and immune therapies for MM has increased considerably in routine practice 2007-2015. Consistent with the results of clinical trials, adoption was associated with substantial increases in survival of patients in the general population.

Mental health services use by melanoma patients receiving adjuvant interferon: association of pre-treatment mental health care with early discontinuation

Background

Although high-dose interferon (hd-ifn) is the sole approved adjuvant systemic treatment for melanoma in many jurisdictions, it is toxic. We sought to assess the population-level effects of hd-ifn toxicity, particularly neuropsychiatric toxicity, hypothesizing that such toxicity would have the greatest effect on mental health services use in advanced resected melanoma.

Methods

This retrospective population-based registry study considered all melanoma patients receiving adjuvant hd-ifn in Ontario during 2008-2012. Toxicity was investigated through health services use compatible with hd-ifn toxicity (for example, mental health physician billings). Using stage data reported from cancer centres about a subset of patients (stages iib-iiic), a propensity-matched analysis compared such service use in patients who did and did not receive hd-ifn. Associations between early hd-ifn discontinuation and health services use were examined.

Results

Of 718 melanoma patients who received hd-ifn, 12% were 65 years of age and older, and 83% had few or no comorbidities. One third of the patients experienced 1 or more toxicity-associated health care utilization events within 1 year of starting hd-ifn. Of 420 utilization events, 364 (87%) were mental health-related, with 54% being family practitioner visits, and 39% being psychiatrist visits. In the propensity-matched analysis, patients receiving hd-ifn were more likely than untreated matched controls to use a mental health service (p = 0.01), with 42% of the control group and 51% of the hd-ifn group using a mental health service in the period spanning the 12 months before to the 24 months after diagnosis. In the multivariable analysis, early drug discontinuation was more likely in the presence of pre-existing mental health issues (odds ratio: 2.0; 95% confidence limits: 1.1, 3.4).

Conclusions

Stage iib-iiic melanoma patients carry a substantial burden of mental health services use whether or not receiving hd-ifn, highlighting an important survivorship issue for these patients. High-dose interferon is associated with more use of mental health services, and pre-treatment use of mental health services is associated with treatment discontinuation. That association should be kept in mind when hd-ifn is being considered.

The population benefit of evidence-based radiotherapy: 5-Year local control and overall survival benefits

BACKGROUND

To describe the population benefit of radiotherapy in a high-income setting if evidence-based guidelines were routinely followed.

METHODS

Australian decision tree models were utilized. Radiotherapy alone (RT) benefit was defined as the absolute proportional benefit of radiotherapy compared with no treatment for radical indications, and of radiotherapy over surgery alone for adjuvant indications. Chemoradiotherapy (CRT) benefit was the absolute incremental benefit of concurrent chemoradiotherapy over RT. Five-year local control (LC) and overall survival (OS) benefits were measured. Citation databases were systematically queried for benefit data. Meta-analysis and sensitivity analysis were performed.

FINDINGS

48% of all cancer patients have indications for radiotherapy, 34% curative and 14% palliative. RT provides 5-year LC benefit in 10.4% of all cancer patients (95% Confidence Interval 9.3, 11.8) and 5-year OS benefit in 2.4% (2.1, 2.7). CRT provides 5-year LC benefit in an additional 0.6% of all cancer patients (0.5, 0.6), and 5-year OS benefit for an additional 0.3% (0.2, 0.4). RT benefit was greatest for head and neck (LC 32%, OS 16%), and cervix (LC 33%, OS 18%). CRT LC benefit was greatest for rectum (6%) and OS for cervix (3%) and brain (3%). Sensitivity analysis confirmed a robust model.

INTERPRETATION

Radiotherapy provides significant 5-year LC and OS benefits as part of evidence-based cancer care. CRT provides modest additional benefits.

The Benefits of Providing External Beam Radiotherapy in Low- and Middle-income Countries

More than half of all cancer diagnoses worldwide occur in low- and middle-income countries (LMICs) and the incidence is projected to rise substantially within the next 20 years. Radiotherapy is a vital, cost-effective treatment for cancer; yet there is currently a huge deficit in radiotherapy services within these countries. The aim of this study was to estimate the potential outcome benefits if external beam radiotherapy was provided to all patients requiring such treatment in LMICs, according to the current evidence-based guidelines. Projected estimates of these benefits were calculated to 2035, obtained by applying the previously published Collaboration for Cancer Outcomes, Research and Evaluation (CCORE) demand and outcome benefit estimates to cancer incidence and projection data from the GLOBOCAN 2012 data. The estimated optimal radiotherapy utilisation rate for all LMICs was 50%. There were about 4.0 million cancer patients in LMICs who required radiotherapy in 2012. This number is projected to increase by 78% by 2035, a far steeper increase than the 38% increase expected in high-income countries. National radiotherapy benefits varied widely, and were influenced by case mix. The 5 year population local control and survival benefits for all LMICs, if radiotherapy was delivered according to guidelines, were estimated to be 9.6% and 4.4%, respectively, compared with no radiotherapy use. This equates to about 1.3 million patients who would derive a local control benefit in 2035, whereas over 615 000 patients would derive a survival benefit if the demand for radiotherapy in LMICs was met. The potential outcome benefits were found to be higher in LMICs. These results further highlight the urgent need to reduce the gap between the supply of, and demand for, radiotherapy in LMICs. We must attempt to address this 'silent crisis' as a matter of priority and the approach must consider the complex societal challenges unique to LMICs.

Quality of Radiation Therapy Referral and Utilisation Post-prostatectomy: A Population-based Study of Time Trends

AIMS

Adjuvant radiotherapy post-prostatectomy has been shown to benefit patients with adverse pathology. It remains unclear whether salvage radiotherapy confers equivalent outcomes. Practice guidelines recommend referral to radiation oncology within 6 months after prostatectomy to discuss adjuvant and salvage radiotherapy. The study objectives were to assess, at a population level: (i) post-prostatectomy referral patterns for radiotherapy; (ii) adjuvant and salvage radiotherapy utilisation; and (iii) time trends in relation to clinical trials and guidelines. These findings provide indications of access to quality care.

MATERIALS AND METHODS

This was a retrospective cohort study. Electronic radiotherapy consultation and treatment records were linked to the population-based Ontario Cancer Registry. The population included prostate cancer cases treated with prostatectomy in Ontario between 2003 and 2012. Radiotherapy referral and treatment rates over time were analysed using the chi-squared trend test.

RESULTS

Over the study period, 30 447 prostate cancer patients received prostatectomy. The proportion seen by radiation oncology within 6 months after prostatectomy doubled from 10.7% in 2003-2004 to 21.7% in 2011-2012 (P < 0.0001 for trend), with the largest annual percentage difference in 2009-2011 (3.4%). Among 4641 patients seen within 6 months, adjuvant radiotherapy rates remained at 51.0% ± 3.0%. Contemporaneous with radiation oncology referral trends, overall adjuvant radiotherapy use increased from 6.2% in 2003-2004 to 11.0% in 2011-2012 (P < 0.001), while salvage radiotherapy remained at 8.4% ± 0.4%. Consequently, the total proportion receiving radiotherapy within 24 months increased from 14.1% in 2003-2004 to 17.7% in 2009-2010 (P < 0.0001).

CONCLUSIONS

There was an increase in access to early radiation oncology referral post-prostatectomy and adjuvant radiotherapy in Ontario between 2003 and 2012, following guideline publication.

A Population-based Model of Local Control and Survival Benefit of Radiotherapy for Lung Cancer

AIMS

To estimate the population-based locoregional control and overall survival benefits of radiotherapy for lung cancer if the whole population were treated according to evidence-based guidelines. These estimates were based on a published radiotherapy utilisation (RTU) model that has been used to estimate the demand and planning of radiotherapy services nationally and internationally.

MATERIALS AND METHODS

The lung cancer RTU model was extended to incorporate an estimate of benefits of radiotherapy alone, and of radiotherapy in conjunction with concurrent chemotherapy (CRT). Benefits were defined as the proportional gains in locoregional control and overall survival from radiotherapy over no radiotherapy for radical indications, and from postoperative radiotherapy over surgery alone for adjuvant indications. A literature review (1990-2015) was conducted to identify benefit estimates of individual radiotherapy indications and summed to estimate the population-based gains for these outcomes. Model robustness was tested through univariate and multivariate sensitivity analyses.

RESULTS

If evidence-based radiotherapy recommendations are followed for the whole lung cancer population, the model estimated that radiotherapy alone would result in a gain of 8.3% (95% confidence interval 7.4-9.2%) in 5 year locoregional control, 11.4% (10.8-12.0%) in 2 year overall survival and 4.0% (3.6-4.4%) in 5 year overall survival. For the use of CRT over radiotherapy alone, estimated benefits would be: locoregional control 1.7% (0.8-2.4%), 2 year overall survival 1.7% (0.5-2.8%) and 5 year overall survival 1.2% (0.7-1.9%).

CONCLUSIONS

The model provided estimates of radiotherapy benefit that could be achieved if treatment guidelines are followed for all cancer patients. These can be used as a benchmark so that the effects of a shortfall in the utilisation of radiotherapy can be better understood and addressed. The model can be adapted to other populations with known epidemiological parameters to ensure the planning of equitable radiotherapy services.

Estimating the population benefit of radiotherapy: using demand models to estimate achievable cancer outcomes

The measurement of population benefits is important for priority setting, economic evaluation and quality improvement. It also informs advocacy. In this article, the use of demand models to estimate the achievable benefit of cancer therapy is reviewed. Achievable benefit refers to the treatment benefit achievable under optimal conditions. The population benefit of radiotherapy has been used as an example. Demand models provide a means of estimating the optimal proportion of patients with treatment indications when guidelines are followed. They may be used to estimate achievable benefit. The choice of end point should reflect the range of benefits associated with the treatment of interest. In some cases, further model development is needed if a pre-existing demand model is used. The benefit of treatment for each indication is estimated using a systematic review process. The highest level of evidence is used to define the benefit for each indication. In cases where multiple sources of the same level and quality of evidence exist, a meta-analysis is carried out. Population-based effectiveness data sources are considered, but three major challenges to their use are: (i) generalisability of the observed outcomes, (ii) data resolution and (iii) confounding and bias. The population benefit determined from this process describes the population proportion achieving a benefit due to the use of guideline-based treatment, compared with no use of that treatment. Sensitivity analysis provides a means for modelling the effect of model uncertainties. The predominant uncertainty is most often due to uncertainty in indication proportion. Preference-sensitive treatment decisions are a common example. The described approach to estimating the achievable benefit of cancer therapy is robust to model uncertainties, rapidly adaptable and is transparent. However, estimates rely on the quality of model data sources and may be affected by model assumptions. Models should be developed for a broader range of modalities of cancer therapy and relevant end points.

The knowledge authoring tool: an XML-based knowledge acquisition environment

As part of an enterprise effort to develop new clinical information systems at Intermountain Health Care, we are developing a Knowledge Authoring Tool that facilitates the development of medical knowledge. At present, users of the application can compose order sets and other clinical knowledge documents based upon XML schemas. The flexible nature of the application allows for the authoring of new types of documents once an XML schema and accompanying web form have been developed and stored in a shared repository. The need for a knowledge acquisition tool stems largely from the desire for medical practitioners to be able to write their own content for clinical use. We hypothesize that knowledge content for clinical use can be successfully implemented around XML-based document frameworks containing structured and coded knowledge.