Delayed Colorectal Cancer Diagnosis during the COVID-19 Pandemic in Alberta: A Framework for Analyzing Barriers to Diagnosis and Generating Evidence to Support Health System Changes Aimed at Reducing Time to Diagnosis

The frequency of colorectal cancer (CRC) diagnosis has decreased due to the COVID-19 pandemic. Health system planning is needed to address the backlog of undiagnosed patients. We developed a framework for analyzing barriers to diagnosis and estimating patient volumes under different system relaunch scenarios. This retrospective study included CRC cases from the Alberta Cancer Registry for the pre-pandemic (1 January 2016–4 March 2020) and intra-pandemic (5 March 2020–1 July 2020) periods. The data on all the diagnostic milestones in the year prior to a CRC diagnosis were obtained from administrative health data. The CRC diagnostic pathways were identified, and diagnostic intervals were measured. CRC diagnoses made during hospitalization were used as a proxy for severe disease at presentation. A modified Poisson regression analysis was used to estimate the adjusted relative risk (adjRR) and a 95% confidence interval (CI) for the effect of the pandemic on the risk of hospital-based diagnoses. During the study period, 8254 Albertans were diagnosed with CRC. During the pandemic, diagnosis through asymptomatic screening decreased by 6·5%. The adjRR for hospital-based diagnoses intra-COVID-19 vs. pre-COVID-19 was 1.24 (95% CI: 1.03, 1.49). Colonoscopies were identified as the main bottleneck for CRC diagnoses. To clear the backlog before progression is expected, high-risk subgroups should be targeted to double the colonoscopy yield for CRC diagnosis, along with the need for a 140% increase in monthly colonoscopy volumes for a period of 3 months. Given the substantial health system changes required, it is unlikely that a surge in CRC cases will be diagnosed over the coming months. Administrators in Alberta are using these findings to reduce wait times for CRC diagnoses and monitor progression.

Generalizability of Landmark Clinical Trials in Diffuse Large B Cell Lymphoma to Real-World Patients: A Single-Centre Retrospective Cohort Study

Background: Clinical trials are the gold standard by which therapies in oncology are evaluated and ultimately form the bases for approval of novel therapies. Stringent eligibility criteria limit the participation of many "real-world" patients and thus undermine the generalizability of trial results. Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of Non-Hodgkin lymphoma (NHL) and is curable in the majority of patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). The addition of rituximab to CHOP is the only clear advancement in DLBCL therapy in the last 20 years. Though a large minority of patients are not cured by R-CHOP, several subsequent novel therapies have failed to demonstrate benefit in Phase 3 clinical trials. We hypothesized that real world patient populations differ from clinical trial populations with trial eligibility excluding the poor-outcome patients who might benefit most from novel therapy. Methods: We performed a retrospective chart review of all patients 18 years of age or older who were registered within the Alberta Cancer Registry with a new diagnosis of pathology-confirmed DLBCL, between January 1, 2010 and December 31, 2011. Clinical characteristics were reviewed to assess patient eligibility to participate in 3 landmark clinical trials for DLBCL on the basis of inclusion and exclusion criteria defined by each study. The trials included Pfreundschuh, M. et al. (2006) and Coiffier, B. et al. (2002), which were assessed together as representing the landmark studies for rituximab added to CHOP, and the GOYA trial (2017) which evaluated obinutuzumab-CHOP vs R-CHOP. Categorical variables are presented as frequencies and percentages. Univariate probabilities of overall-survival were calculated by Kaplan-Meier method. Results: We identified 480 patients with a diagnosis of DLBCL within the Alberta Cancer Registry. A total of 390 patients were eligible for our study with 20 patients excluded for CNS lymphoma, 29 for unclassifiable B-cell lymphoma, 2 patients who died at the time of diagnosis, and 25 patients with previously treated indolent lymphoma. In addition, 14 patients were excluded for insufficient clinical data. Table 1 demonstrates the clinical characteristics of the population. Out of 390 patients, only 130 (33%) patients met inclusion for the rituximab studies and 134 (34%) for the GOYA study. Table 2 demonstrates the most common criteria leading to trial exclusion, including poor performance status, limited stage disease, inappropriate IPI, transformed lymphoma, history of second primary malignancy, and viral infections. Trial ineligible patients had significantly inferior overall survival compared to trial eligible patients (Figure1). Conclusions: The majority of real-world DLBCL patients are excluded from clinical trials and have inferior outcomes compared to trial eligible patients. The selection of patients with more favourable outcomes for clinical trials may contribute to failure to demonstrate a benefit of novel therapies. Broadening inclusion criteria to include patients with transformed disease and poor performance status could aid in improving the generalisability of DLBCL clinical trials. Disclosures Stewart: Gilead: Honoraria; Roche: Honoraria; Celgene: Honoraria; Amgen: Honoraria; Abbvie: Honoraria; Janssen: Honoraria; Teva: Honoraria; Sandoz: Honoraria; AstraZeneca: Honoraria; Novartis: Honoraria. Owen:AbbVie, F. Hoffmann-La Roche, Janssen, Astrazeneca, Merck, Servier, Novartis, Teva: Honoraria.

Eligibility of real-world patients with stage II/III colorectal cancer (CRC) in adjuvant chemotherapy (AC) trials.

50 Background: The results of AC trials in stage II/III CRC are often generalized to real-world patients. However, clinical trials have stringent inclusion and exclusion criteria, which can potentially lead to poor generalizability of results and slow accrual. This study was conducted to determine the proportion of real-world patients with stage II/ III CRC who would be eligible for AC trials based on common eligibility criteria and to compare the outcomes in eligible and ineligible patients. Methods: We identified all patients diagnosed with stage II/III CRC in 2004-2015 from the Alberta Cancer Registry. Patients meeting any one of the following criteria were considered ineligible: age >75 years, anemia, comorbid conditions (heart disease, uncontrolled diabetes, kidney disease, liver disease) and history of a prior malignancy or immunosuppression. Logistic regression was used to describe the likelihood of receiving AC and Cox regression models were constructed to determine overall survival (OS). Results: A total of 7841 patients with stage II/III CRC were identified, of whom 52% were men and median age at diagnosis was 71 years (IQR: 61-79 years). Approximately 59% patients were deemed trial-ineligible and the most common reasons for ineligibility were advanced age (36%), renal dysfunction (27%), and cardiac disease (17%), respectively. In the real-world, 54% of eligible patients received AC as compared to 23% of ineligible patients [odds ratio 3.89, 95% confidence interval (CI) 3.53-4.28, P< 0.0001]. The 5-year OS of trial-ineligible patients who received AC was significantly better than those treated with surgery alone (table). Conclusions: Majority of real-world patients with stage II/ III CRC are unable to participate in AC trials due to strict exclusion criteria, but a fair proportion of these patients still derive some benefit from AC. The eligibility criteria of AC trials in CRC should be broadened to be more representative of real-world patients. [Table: see text]

Adjustments in relative dose intensity (RDI) for FECD chemotherapy in breast cancer: A population analysis.

547 Background: Reductions in RDI of adjuvant chemotherapy for breast cancer (BC) has been associated with inferior survival. However, earlier studies may be confounded by uncharacterized BC subtype(s) (TNBC, HER2+) and non-taxane chemotherapy regimens (CMF, AC). This retrospective study evaluates survival (DFS/OS) outcomes for patients receiving RDI reductions for FECD adjuvant chemotherapy in Alberta, Canada. Methods: Patients with stage I-III, ER +/-, HER2- BC receiving adjuvant FECD chemotherapy from 2007-2014 were identified using the Alberta Cancer Registry. RDI of individual chemotherapeutics (cycle 1-6) were recorded. Average RDI was stratified by <85% vs ≥85% of total dose. Subgroup analysis for early (cycle 1-3) versus late (cycle 4-6) RDI reductions were evaluated. Events (recurrence/death) from any cause were identified. Results: FECD patients (n=1304) receiving an average RDI <85% (range 25-84%) compared to ≥85% demonstrated a significant decline in DFS (79% vs 85%; p<0.01) and OS (82% vs 89%; p<0.01). Early reductions (any) compared to no reduction in RDI were correlated with inferior DFS (77% vs 86%; p<0.01) and OS (79% vs 90%; p<0.01). Late reductions in RDI did not affect DFS/OS. Proportions of TNBC were non-significant for comparative cohorts. Significantly more N0 and N1-3 patients were seen in the any and no early reduction cohort respectively. Conclusions: In high risk BC patients, average RDI <85% is correlated with reduced DFS/OS for FECD. Early (FEC) compared with late (docetaxel) reductions in RDI are correlated with inferior survival. This data suggests that where possible, total (<85%) and early (FEC) dose reductions should be avoided in patients receiving adjuvant FEC-D chemotherapy. [Table: see text]

An audit of referral and treatment patterns of high-risk prostate cancer patients in Alberta

Introduction: We aimed to determine the impact of clinical practice guidelines (CPG) on rates of radiation oncologist (RO) referral, androgen-deprivation therapy (ADT), radiation therapy (RT), and radical prostatectomy (RP) in patients with high-risk prostate cancer (HR-PCa).Methods: All men >18 years, diagnosed with PCa in 2005 and 2012 were identified from the Alberta Cancer Registry. Patient age, aggregated clinical risk group (ACRG) score, Gleason score (GS), pre-treatment prostate-specific antigen (PSA), RO referral, and treatment received were extracted from electronic medical records. Logistic regression modelling was used to examine associations between RO referral rates and relevant factors.Results: HR-PCa was diagnosed in 261 of 1792 patients in 2005 and 435 of 2148 in 2012. Median age and ACRG scores were similar in both years (p>0.05). The rate of patients with PSA >20 were 67% and 57% in 2005 and 2012, respectively (p=0.004). GS ≤6 was found in 13% vs. 5% of patients, GS 7 in 27% vs. 24%, and GS ≥8 in 59% vs. 71% in 2005 and 2012, respectively (p<0.001). In 2005, RO referral rate was 68% compared to 56% in 2012 (p=0.001), use of RT + ADT was 53% compared to 32% (p<0.001), and RP rate was 9% vs. 17% (p=0.002). On regression analysis, older age, 2012 year of diagnosis and higher PSA were associated with decreased RO referral rates (odds ratios [OR] 0.49, 95% confidence interval [CI] 0.39–0.61; OR 0.51, 95% CI 0.34–0.76; and OR 0.64, 95% CI 0.39–0.61), respectively [p<0.001]).Conclusions: Since CPG creation in 2005, RO referral rates and ADT + RT use declined and RP rates increased, which demonstrates a need to improve adherence to CPG in the HR-PCa population.

An investigation of cancer incidence in a First Nations community in Alberta, Canada, 1995–2006

Objective To determine colorectal and overall cancer incidence as part of a three-pronged investigation in response to the concerns of a First Nations community in Alberta, Canada, located close to sulfur-rich natural gas installations, and to determine whether the incidence of cancers observed in this reserve was higher than expected. Methods A population dataset with information identifying First Nations status and band affiliation was linked to the Alberta Cancer Registry to determine cancer incidence cases between 1995 and 2006 for on- and off-reserve study populations. Using indirect standardized incidence ratios, observed cancer incidence cases for the study populations were compared with cases expected based on three separate reference populations. Results Observed colorectal and overall cancer incidence cases within the First Nations community were not higher than expected. Cervical cancer incidence cases, however, were higher than expected for on- and off-reserve populations; public health measures designed to address this risk have been implemented and on-going surveillance of cancer incidence in the community will be maintained.

Population-based Study of Medulloblastoma: Outcomes in Alberta from 1975 to 1996

Background:The purpose of this study was to determine incidence, survival rate, and prognostic factors as well as the frequency of Collins’ Law Violators (CLVs) in an unselected population of medulloblastoma patients. Collins’ Law dictates that ’cure’ of a child with a tumor occurs after a period that includes the child’s age at diagnosis plus 9 months.Methods:Using the Alberta Cancer Registry a population-based review identified 49 patients with medulloblastoma (19 adults, 30 children) diagnosed from 1975-96. Pathology was reviewed in all cases. All patients had surgical resection, followed by radiotherapy in 47 patients and chemotherapy in 17.Results:The overall 5-year survival was 50%. There was a trend for the extent of resection to be associated with a longer survival (Long rank test, p< 0.06) but this was not significant. Tumor recurrence occurred a median of 22.4 months (range, 6.4-192.3) after diagnosis and median survival after recurrence was 9.3 months (range, 0.4-64.9). The survival curve did not appear to plateau but was affected by tumor-related deaths in 3 (21.4%) of the 21 long-term survivors diagnosed in childhood. These three patients had recurrences a mean of 11.7 years after diagnosis and are designated as CLVs.Conclusions:The survival rate in an unselected population of patients with medulloblastoma is poor. Aggressive resection of the tumors prolongs survival. The Collins’ Law Violators were relatively common and we suggest this concept be abandoned in medulloblastoma.