Comparison of Treatment, Cost, and Survival in Patients With Metastatic Colorectal Cancer in Western Washington, United States, and British Columbia, Canada

CDK4/6 Inhibitor Efficacy in ESR1-Mutant Metastatic Breast Cancer

BACKGROUND

In estrogen receptor-positive metastatic breast cancer, ESR1 mutations (ESR1m) are a common mechanism of acquired resistance to aromatase inhibitors (ArIh). However, the impact ESR1 alterations have on CDK4/6 inhibitor (CDK4/6i) sensitivity has not been established. Analyses of CDK4/6i trials suggest that the endocrine therapy partner and specific ESR1 allele may affect susceptibility. We analyzed a real-world data set to investigate CDK4/6i efficacy in ESR1m metastatic breast cancer and associated clinical factors.

METHODS

ESR1m were identified by analysis of circulating-tumor deoxyribonucleic acid. The GuardantINFORM database contains genomic information from tumors linked with claims data. Patients who started a CDK4/6i within 30 days of sequencing were categorized as having ESR1m or non-ESR1-mutant (non-ESR1m) breast cancer. Data were analyzed to determine the real-world time-to-next-treatment, defined as the start of a breast cancer treatment to initiation of the subsequent treatment.

RESULTS

One hundred forty-five patients with ESR1m and 612 with non-ESR1m metastatic breast cancer were analyzed. ESR1m and non-ESR1m tumors had similar real-world time-to-next-treatment on CDK4/6i regimens (hazard ratio, 1.02; 95% confidence interval, 0.82 to 1.23). Duration on therapy in the first-line and second-line plus treatment settings were comparable regardless of ESR1 status. We stratified treatment duration by concurrent endocrine therapy, and patients with ESR1m had worse outcomes on ArIh but comparable real-world time-to-next-treatment on fulvestrant.

CONCLUSIONS

These data suggest ESR1 variants are not associated with pan-CDK4/6i resistance and are consistent with the hypothesis that CDK4/6 blockade combined with a selective estrogen receptor degrader is potentially an effective option for ESR1m metastatic breast cancer.

Treatment Patterns and Outcomes in Pancreatic Cancer: A Comparative Analysis of Ontario and the USA

BACKGROUND

Comparative studies evaluating quality of care in different healthcare systems can guide reform initiatives. This study seeks to characterize best practices by comparing utilization and outcomes for patients with pancreatic cancer (PC) in the USA and Ontario, Canada.

METHODS

Patients (age ≥ 66 years) with PC were identified from the Ontario Cancer Registry and SEER-Medicare databases from 2006 to 2015. Demographics and treatment (surgery, radiation, chemotherapy, or multimodality (surgery and chemotherapy)) were described. In resected patients, neoadjuvant therapy, readmission, and 30- and 90-day postoperative mortality rates were calculated. Survival was assessed using Kaplan-Meier curves.

RESULTS

This study includes 38,858 and 11,512 patients with PC from the USA and Ontario, respectively. More female patients were identified in the USA (54.0%) versus Ontario (46.9%). In the entire cohort, US patients received more radiation in addition to other therapies (18.8% vs. 13.5% Ontario) and chemotherapy alone (34.3% vs. 19.0% Ontario). While rates of resection were similar (13.4% USA vs.12.5% Ontario), multimodality therapy was more common in the UAS (9.0% vs. 6.4%). Among resected patients, neoadjuvant chemotherapy was uncommon in both groups, although more frequent in the USA (12.0% vs. 3.2% Ontario). The 30- and 90-day postoperative mortality rates were lower in Ontario vs. the USA (30-day: 3.26% vs. 4.91%; 90-day: 7.08% vs. 10.96%), however, overall survival was similar between the USA and Ontario.

CONCLUSIONS

We observed substantive differences in treatment and outcomes between PC patients in the USA and Ontario, which may reflect known differences in healthcare systems. Close evaluation of healthcare policies can inform initiatives to improve care quality.

Pan-Cancer Prevalence of Microsatellite Instability-High (MSI-H) Identified by Circulating Tumor DNA and Associated Real-World Clinical Outcomes

PURPOSE

Immune checkpoint inhibitors are approved for advanced solid tumors with microsatellite instability-high (MSI-H). Although several technologies can assess MSI-H status, detection and outcomes with circulating tumor DNA (ctDNA)-detected MSI-H are lacking. As such, we examined pan-cancer MSI-H prevalence across 21 cancers and outcomes after ctDNA-detected MSI-H.

METHODS

Patients with advanced cancer who had ctDNA testing (Guardant360) from October 1, 2018, to June 30, 2022, were retrospectively assessed for prevalence. GuardantINFORM, which includes anonymized genomic and structured payer claims data, was queried to assess outcomes. Patients who initiated new treatment within 90 days of MSI-H detection were sorted into immunotherapy included in treatment (IO) or no immunotherapy included (non-IO) groups. Real-world time to treatment discontinuation (rwTTD) and real-world time to next treatment (rwTTNT) were assessed in months as proxies of progression-free survival (PFS); real-world overall survival (rwOS) was assessed in months. Cox regression tests analyzed differences. Colorectal cancer, non-small-cell lung cancer (NSCLC), prostate cancer, gastroesophageal cancer, and uterine cancer (UC) were assessed independently; all other cancers were grouped.

RESULTS

In total, 1.4% of 171,881 patients had MSI-H detected. Of 770 patients with outcomes available, rwTTD and rwTTNT were significantly longer for patients who received IO compared with non-IO for all cancers (P ≤ .05; hazard ratio [HR] range, 0.31-0.52 and 0.25-0.54, respectively) except NSCLC. rwOS had limited follow-up for all cohorts except UC (IO 39 v non-IO 23 months; HR, 0.18; P = .004); however, there was a consistent trend toward prolonged OS in IO-treated patients.

CONCLUSION

These data support use of a well-validated ctDNA assay to detect MSI-H across solid tumors and suggest prolonged PFS in patients treated with IO-containing regimens after detection. Tumor-agnostic, ctDNA-based MSI testing may be reliable for rapid decision making.

Cost-Effectiveness of Surveillance after Metastasectomy of Stage IV Colorectal Cancer

Surveillance of stage IV colorectal cancer (CRC) after curative-intent metastasectomy can be effective for detecting asymptomatic recurrence. Guidelines for various forms of surveillance exist but are supported by limited evidence. We aimed to determine the most cost-effective strategy for surveillance following curative-intent metastasectomy of stage IV CRC. We performed a decision analysis to compare four active surveillance strategies involving clinic visits and investigations elicited from National Comprehensive Cancer Network (NCCN) recommendations. Markov model inputs included data from a population-based cohort and literature-derived costs, utilities, and probabilities. The primary outcomes were costs (2021 Canadian dollars) and quality-adjusted life years (QALYs) gained. Over a 10-year base-case time horizon, surveillance with follow-ups every 12 months for 5 years was most economically favourable at a willingness-to-pay threshold of CAD 50,000 per QALY. These patterns were generally robust in the sensitivity analysis. A more intensive surveillance strategy was only favourable with a much higher willingness-to-pay threshold of approximately CAD 425,000 per QALY, with follow-ups every 3 months for 2 years then every 12 months for 3 additional years. Our findings are consistent with NCCN guidelines and justify the need for additional research to determine the impact of surveillance on CRC outcomes.

Comparison of Health Care Utilization at the End of Life Among Patients With Cancer in Alberta, Canada, Versus Washington State

PURPOSE

Aggressive care at the end of life (EOL) can lead to unnecessary suffering and health care costs for patients with cancer. Despite geographic proximity and cultural similarities, we hypothesize that EOL care is more intense in the United States multipayer system versus the Canadian single-payer system. We compared health care utilization at EOL among patients with cancer in Alberta, Canada, with those in Washington state in the United States.

METHODS

Adult patients with American Joint Committee on Cancer stage II to IV solid tumors who died between 2014 and 2016 in Alberta and between 2015 and 2017 in Washington were identified from regional population-based cancer registries linked to treatment and hospitalization records (Alberta) and health claims from major regional insurance plans (Washington). The proportion of patients receiving chemotherapy and having multiple emergency department (ED) visits, or intensive care unit (ICU) admissions in the last 30, 60, and 90 days of life (DOL) in Alberta and Washington were determined and compared using two-sample z-test and multivariable logistic regression (α = .006 after Bonferroni correction).

RESULTS

Of patients, 11,177 in Alberta and 12,807 in Washington were included. Patients were similar in age (median, 71 v 72 year), with more patients in Washington with no comorbidities. More patients in Washington were treated with chemotherapy (12.6% v 6.6%; adjusted OR [aOR], 2.74), had multiple ED visits (16.2% v 12.1%; aOR, 1.40), and ICU admissions (23.7% v 3.9%; aOR, 14.27) in the last 30 DOL. Utilization was also higher in Washington in the last 60 and 90 DOL and among those with stage IV disease and those age 65 years and older.

CONCLUSION

Utilization of chemotherapy, ED visits, and ICU admissions near EOL was higher in Washington versus Alberta. Future studies to characterize drivers of aggressive EOL care may help improve cancer care for patients in the United States and Canada.