No treatment strategy that incorporated the Oncotype DX DCIS Score test appeared cost-effective for patients with ductal carcinoma in situ considering adjuvant radiation therapy, according to research published in Journal of Clinical Oncology.
However, use of the assay correlated with a lower proportion of women undergoing radiation per ipsilateral breast event, results showed.
Ductal carcinoma in situ (DCIS) accounts for approximately 25% of breast cancers diagnosed in the United States. Breast-conserving surgery and radiation therapy serve as a standard of care for DCIS; however, randomized studies have suggested that many women can omit adjuvant radiation therapy without significantly increasing their risk for an ipsilateral breast event.
The Oncotype DX DCIS Score (Genomic Health) is a genetic test that estimates the risk for an ipsilateral breast event in patients treated with breast-conserving surgery.
“Two studies have shown its ability to predict the 10-year risk [for] developing an ipsilateral breast event in patients treated with breast-conserving surgery without adjuvant radiation therapy, suggesting the potential to use this test to select women who may be treated with surgery alone,” Ann C. Raldow, MD, MPH, assistant professor of radiation oncology at UCLA’s David Geffen School of Medicine, and colleagues wrote. “However, such genomic assays are expensive, and the optimal strategy for their use remains unclear.”
Raldow and colleagues sought to determine the cost-effectiveness — defined as $100,000 per quality-adjusted life-year or less — of different strategies that used the assay to guide treatment in this patient population.
The researchers constructed a Markov model that simulated 10-year outcomes to consider hypothetical testing strategies for women aged 60 years. The patient population was based on the ECOG E5194 trial, which included women with low- or intermediate-grade DCIS ( 2.5 cm; cohort 1) and high-grade DCIS ( 1 cm; cohort 2).
The researchers considered five strategies:
- no testing and no radiation therapy (strategy 1);
- no testing and radiation therapy only for cohort 2 (strategy 2);
- no radiation therapy for low-grade DCIS and testing for intermediate- or high-grade DCIS, with radiation therapy for intermediate- or high-risk scores (strategy 3);
- testing for all and radiation therapy for intermediate- and high-risk scores (strategy 4); and
- no testing with radiation therapy for all (strategy 5).
The researchers used data from available literature and Medicare claims to determine incremental cost-effectiveness ratios and the number of women needed to irradiate to prevent one ipsilateral breast event.
None of the treatment strategies appeared cost-effective compared with the reference strategy of observation after breast-conserving surgery.
Mean per-person costs ranged from $1,360 for strategy 1 to $10,969 for strategy 5.
Strategy 1 was the favored approach in a sensitivity analysis that varied the relative risk reduction conferred by radiation between 25% and 100% at a willingness-to-pay threshold of $100,000 per quality-adjusted life-year. No strategy was cost-effective relative to observation when researchers compared different risk reductions across low- and high-risk patients.
The researchers analyzed costs per ipsilateral breast event and invasive breast cancer prevented, using strategy 1 as reference. This analysis showed strategy 2 was the most cost-effective, at $108,300 per ipsilateral breast event and $214,891 per invasive breast cancer prevented.
Compared with strategy 1, the number of patients needed to irradiate to prevent one ipsilateral breast event ranged from 7.5 for strategy 4 to 13.1 for strategy 5. For the prevention of invasive breast cancer, the number needed to irradiate ranged from 13.8 for strategy 4 to 29.7 for strategy 5.
There are several limitations of the analysis, according to the researchers.
“First, we made some simplifying assumptions about the natural history and treatment of disease to specify a finite number of clinical events,” they wrote. “Second, we did not explore the impact of uncertainty in model input parameters on results across multiple parameters simultaneously.”
These findings suggest patient preferences are key in determining treatments, the researchers added.
“Given current parameters, radiation therapy was not cost-effective unless the utility of a patient who had not undergone radiation therapy was lower than that of a patient who had undergone radiation therapy, at which point treating all patients was favored,” Raldow and colleagues wrote. “Therefore, physicians should elicit individual patient preferences to maximize quality-of-life outcomes.” – by Cameron Kelsall
Disclosure: One study researcher reports consultant roles with CareCore and U.S. Oncology and institutional research funding from Genomic Health. Raldow and the other researchers report no relevant financial disclosures.