Why can't you have radiotherapy twice
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Why Can't You Have Radiotherapy Twice?
Radiotherapy is a common treatment for various cancers, including limited-stage small-cell lung cancer (LS-SCLC). However, undergoing radiotherapy more than once is generally not recommended due to several critical factors related to treatment efficacy, patient safety, and potential adverse effects.
Radiotherapy Dose and Schedule Optimization
Twice-Daily vs. Once-Daily Radiotherapy
Studies have shown that twice-daily radiotherapy (BID) can be more effective than once-daily radiotherapy (QD) for certain cancers, including LS-SCLC. For instance, a trial comparing 45 Gy in 30 fractions twice daily with 66 Gy in 33 fractions once daily found no significant difference in overall survival between the two regimens, but twice-daily treatment was associated with higher rates of severe neutropenia . Another study demonstrated that twice-daily radiotherapy significantly improved survival compared to once-daily radiotherapy, with median survival rates of 23 months versus 19 months, respectively.
High-Dose Radiotherapy
Increasing the radiotherapy dose has been explored to improve outcomes. A study comparing 60 Gy in 40 fractions twice daily with 45 Gy in 30 fractions found that the higher dose improved survival without increasing toxicity. However, another trial found no significant survival benefit when comparing 70 Gy once daily with 45 Gy twice daily, suggesting that higher doses do not always translate to better outcomes.
Adverse Effects and Toxicity
Acute and Long-Term Toxicity
Radiotherapy, especially when administered twice daily, can lead to significant acute and long-term toxicities. Common adverse effects include neutropenia, esophagitis, and pneumonitis. For example, a study reported that grade 3 esophagitis was more frequent in patients receiving twice-daily radiotherapy compared to those receiving once-daily treatment. Another trial found similar toxicity profiles between once-daily and twice-daily regimens, but with a higher incidence of severe neutropenia in the twice-daily group.
Treatment-Related Mortality
The risk of treatment-related mortality is another critical factor. Studies have reported treatment-related deaths in both once-daily and twice-daily radiotherapy groups, although the rates were generally low. For instance, one study noted three treatment-related deaths in both the 60 Gy and 45 Gy groups.
Practical Considerations
Patient Performance and Logistics
The decision to use once-daily or twice-daily radiotherapy often depends on practical considerations such as patient performance status and logistical factors. A survey of European thoracic radiation oncologists revealed that the choice between QD and BID regimens is influenced by factors like patient ability to travel to the radiotherapy site and radiotherapy dose constraints.
Prophylactic Cranial Irradiation
Prophylactic cranial irradiation (PCI) is often offered to responders to prevent brain metastases, adding another layer of complexity to the treatment regimen. Both once-daily and twice-daily radiotherapy regimens have been used in conjunction with PCI, with no significant differences in overall survival .
Conclusion
Undergoing radiotherapy more than once is generally not recommended due to the cumulative toxicity and potential adverse effects associated with repeated treatments. While optimizing the radiotherapy dose and schedule can improve outcomes, the risk of severe side effects and treatment-related mortality must be carefully balanced. Practical considerations, including patient performance status and logistical factors, also play a crucial role in determining the appropriate radiotherapy regimen. Therefore, the decision to undergo radiotherapy should be made on a case-by-case basis, considering all these factors to ensure the best possible outcome for the patient.
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