Radiation therapy center volume linked to survival among patients with cancer
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Treatment at high-volume radiation therapy facilities correlated with improved survival among select patients with common malignancies, according to study results published in Cancer.
Patients who receive radiation therapy in the definitive setting without surgery may benefit most from treatment at high-volume centers, researchers wrote.
“That undergoing surgery at high-volume centers improves outcomes for cancer has been well-studied, including by our group,” Leila Tchelebi, MD, assistant professor in the department of radiation oncology, and Nicholas Zaorsky, MD, MS, assistant professor in the departments of radiation oncology, radiology and public health services, both of Penn State Cancer Institute, wrote in a joint statement to Healio. “The purpose of our study was to determine if receiving radiation at a high-volume center, regardless of surgery, is associated with improved survival for [patients with cancer].”
The analysis included 253,422 patients with solid tumors who received curative-intent radiation therapy across 1,289 facilities from 2004 to 2013. Among them, 6,231 received neoadjuvant radiation (average age, 60 years; 64.3% men; 84% white), 99,211 received definitive radiation without surgery (average age, 67 years; 73.3% men; 81.7% white) and 147,980 received adjuvant radiation (average age, 61 years; 88.8% women; 83% white).
Researchers classified radiation therapy facilities as low, intermediate, high or very high volume, and they separated primary cancer sites into neoadjuvant, adjuvant or definitive radiation subgroups.
Most patients (78.1%) who underwent adjuvant radiation had breast cancer, whereas the majority of patients (73%) who underwent neoadjuvant radiation had rectal cancer. The most common cancers among those treated with definitive radiation included prostate (38.6%), non-small cell lung (28.4%) and head and neck (16.5%).
Survival following receipt of radiation served as the primary outcome.
Results showed significant improvement in survival for patients who received adjuvant radiation at very high-volume vs. low-volume facilities (HR = 0.8; 95% CI, 0.75-0.85), including patients with cancer of the breast (HR = 0.83; 95% CI, 0.77-0.9) or uterus (HR = 0.77; 95% CI, 0.62-0.97). Researchers observed incremental improvement in relative risk for death as facility volume increased.
Patients receiving definitive radiation at very high-volume vs. low-volume facilities also demonstrated a survival benefit (HR = 0.87; 95% CI, 0.84-0.9), with incremental improvement in relative risk for death as facility volume increased. Patients with NSCLC and head and neck cancer who received definitive radiation at high-volume facilities experienced the greatest benefit.
Among patients treated with radiation in the neoadjuvant setting, researchers observed no difference in survival overall according to facility volume (HR = 0.9; 95% CI, 0.77-1.05); however, patients with rectal cancer treated at very high-volume vs. low-volume facilities demonstrated improvement in survival (HR = 0.75; 95% CI, 0.6-0.94).
The findings validated previous data, according to Tchelebi and Zaorsky.
“However, this was the first study to look at [patients with cancer] with a variety of primary tumor sites and to specifically analyze the impact of radiation therapy volume on survival in patients while accounting for the receipt of surgery, which is well-known to impact survival,” they added.
“For the majority of patients with solid malignancies commonly treated with radiation therapy with curative intent, treatment at a high-volume center is associated with improved survival,” Tchelebi and Zaorsky continued. “This is especially true for patients receiving radiation therapy alone, without surgery.”
Study limitations included an inability to account for selection bias —patients treated at higher-volume centers may be inherently healthier or lower-risk, and patients with a higher income and education level have access to more resources, including the ability to travel to higher-volume centers. Researchers also noted that combining different disease sites and stages can cause intricacies of each cancer type to become lost in such analyses.
Tchelebi and Zaorsky called for further research into why patients treated at high-volume radiation centers have better outcomes.
“Is it because of expertise on the part of the treating physicians? Better support services? More resources?” they said. “By understanding the factors that improve outcomes for [patients with cancer], we can strive to implement changes so that all patients receive the highest standard of cancer care.”
For more information:
Leila Tchelebi, MD, can be reached at Department of Radiation Oncology, Penn State Cancer Institute, 500 University Drive, Hershey, PA 17033; email: ltchelebi@pennstatehealth.psu.edu.
Nicholas Zaorsky, MD, MS, can be reached at Department of Radiation Oncology, Penn State Cancer Institute, 500 University Drive, Hershey, PA 17033; email: nicholaszaorsky@gmail.com.
Perspective
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Timothy Kegelman, MD, PhD
Tchelebi and colleagues provide a wide-ranging look into the correlation of radiation treatment center volumes and survival outcomes. As they noted, previous efforts in this area have been dominated by the surgical literature, which have pointed to benefits of operations performed at high-volume centers. In this work, the authors examine an impressive breadth of cancer types and draw similar conclusions with respect to radiation treatment.
Although one expects there may be significant overlap between high-volume surgical facilities and high-volume radiation facilities, the authors attempted to extricate the relationship of the two by controlling for surgery performed. However, excluded is a large cohort of patients who did not receive all their treatment at one center. Investigating this subset of patients offers potential support for the authors’ conclusions. Consider breast cancer, for example: If high-volume radiation facilities retained their correlation with survival outcomes for patients treated at low-volume surgical centers, this may more strongly support the conclusions as stated.
The weaknesses of similar large database studies are well-known and acknowledged by the authors. Chief among these are the inherent differences among patients treated at high-volume centers compared with others. Efforts to control for these differences are always imperfect and were attempted here through multivariate analysis, controlling for such variables as income, comorbidity score and distance traveled. Nonetheless, the results regarding definitive prostate cancer treatment raise concern that these corrections may fall short.
It was unexpected that differences were found in 5-year survival for treatment of nonmetastatic prostate cancer, a group likely dominated by low- and intermediate-risk disease. Are there differences in radiation delivered at very high-volume centers that confer a survival benefit when one was not observed among men randomly assigned to active surveillance, surgery or radiation on ProtecT? A more likely result is there are important variations manifested when patients are sorted by volume of treatment facility that are not adequately captured by the National Cancer Database.
Nonetheless, the authors deserve to be lauded for their efforts that likely will raise interesting questions and subjects for further research. Although this work focused on facility volume, does individual physician volume play a role in radiation outcomes? What aspects of treatment are important to be disseminated effectively from high-volume to low-volume centers? As subsequent questions are being explored, it is imperative that we continue to recognize the valuable role real-world data can have in clinical practice while exercising caution in attributing correlation to impact.
References:
Neal DE, et al. Eur Urol. 2020;doi:10.1016/j.eururo.2019.10.030.
Yang DX, et al. JAMA Netw Open. 2021;doi:10.1001/jamanetworkopen.2021.1793.
Hospital of the University of Pennsylvania
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