Increased radiation dose after missed treatments may benefit some patients with NSCLC
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Some patients with non-small cell lung cancer who miss radiation treatments may benefit from higher radiation doses, according to a study presented at American Society for Radiation Oncology (ASTRO) Annual Meeting.
The research from Fox Chase Cancer Center showed that for patients with stage III NSCLC undergoing radiation, the risk for death increases in proportion to the number of missed treatments. However, increased doses for patients who miss a modest number of treatments may mitigate this risk.
Individuals who receive radiation for lung cancer generally undergo intensive treatment over a long period, often 5 days a week for up to 6 weeks. During this period, it is not uncommon for patients to miss a few treatment days due to weather, illness or other reasons. These treatment days are made up later, prolonging treatment.
“For the most part, we assure patients, saying, ‘It’s not a big deal; you can miss a day. We can add it on at the end, no problem,” lead author Peter Lee, MD, PhD, radiation oncology resident in the department of radiation oncology at Fox Chase, said in a press release. “But at the same time, we do know that, ideally, you should get treatment done as prescribed and not miss any days.”
The study is part of a larger movement toward more personalized cancer care, according to Lee.
“Ideally, we can begin to adapt treatment to the individual patient,” he said. “So, if a patient misses a certain number of days, we can change their prescription and add on a higher dose as they finish their treatment.”
In the study, Lee and colleagues assessed data on 26,101 patients with stage III NSCLC who underwent chemoradiation and no other treatment between 2004 and 2017. Of these individuals, 8,644 experienced prolonged treatment due to missed days. Nearly half (46.5%) had delays of 1 to 3 days, whereas 18.6% had delays of 4 to 6 days, 12.9% had delays of 7 to 9 days, and the remainder had delays of 10 days or longer.
All patients received radiation doses within the standard of care, but 3,809 received a total dose of 60 Gy and 1,924 received a slightly higher overall dose of 66 Gy.
The researchers found that although there was not a threshold of missed treatment days that prompted increased mortality, the risk for death did increase steadily in relation to the number of days a patient missed.
Moreover, they identified an apparent window where a higher dose of radiation may balance out the missed treatment days. Specifically, low-dose patients who skipped 4 to 9 treatment days had a significantly higher mortality risk than patients who received the higher radiation dose (HR = 1.2; 95% CI, 1.06-1.38).
“Patients who were delayed by 10 or more days didn’t see this benefit,” Lee said in the press release. “That may suggest that once you reach that point, the higher dose isn’t going to make up for missing so many days.”
Lee added that although the study identified a clear association between missed treatments and mortality, this relationship may not be causal. Patients who missed treatment days due to illness or adverse events may have been more severely ill when they began treatment and more likely to die of other causes.
The researchers plan to conduct another study of patients with lung cancer undergoing surgery and chemotherapy in addition to radiation therapy.
References :
- Higher radiation dose may sometimes balance out delayed treatment sessions, study finds (press release). Available at: www.foxchase.org/news. Published Oct. 21, 2022.
- Lee P, et al. Abstract 2846. Presented at: ASTRO Annual Meeting; Oct. 23-26, 2022; San Antonio.
Perspective
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Kevin Stephans, MD
Historical data in lung, gynecologic, and head and neck cancers have suggested that treatment interruptions resulting in prolongation of curative radiation dose regimens have a negative effect on OS.In this study, researchers examined a large national database to identify 8,644 patients (out of a group of 26,101) who had their treatment extended by more than 2 days from their planned completion due to treatment interruption of any cause. Extending treatment by an additional 3 days appeared consistently associated with decreased survival, even as treatment was additionally extended through 15 additional days. It is not clear whether this is causative or just correlative in this retrospective database, as the factor causing delay may be directly associated with decreased survival as much as the delay itself. Physicians already work to avoid delays, except in circumstances where they are unavoidable.
More valuable due to the potential for intervention, the authors further note that increased radiation dose — 66 Gy compared with the more standard regimen of 60 Gy — appeared associated with reduced risk for death among patients extended by 4 to 9 days (risk did not vary from 60 Gy among those with shorter or longer delays). Although it requires validation in additional datasets, this suggests the possibility that increasing radiation dose might overcome the negative effect of these modest treatment delays, giving radiation oncologists a potential action consideration in this group. Although retrospective data does not confirm causation, increasing radiation dose from 60 Gy to 66 Gy for patients who have experienced modest treatment delays offers a very feasible and clinically reasonable intervention. As such, this study offers valuable data to support an intervention that many practices likely already consider, but didn’t previously know how to quantitate and validate.
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Lee P, et al. Abstract 2846. Presented at: ASTRO Annual Meeting; Oct. 23-26, 2022; San Antonio.
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