Prospective Evaluation of Limited Stage Small Cell Lung Cancer (LS-SCLC) Fractionation Regimen Usage and Toxicity in a Large Statewide Quality Collaborative

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Conference Proceeding

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International Journal of Radiation Oncology Biology Physics


Purpose/Objective(s) National guidelines on LS-SCLC treatment give preference to a hyperfractionated regimen of 45 Gy in 30 fractions (Fx) delivered twice-daily (BID) but allow for daily fractionation (QD) to 60-70 Gy in certain circumstances. Use of the BID regimen has been reportedly low, however this is based upon small retrospective series, national databases that lack radiation treatment specifics, or survey data. We sought to characterize the fractionation regimens used to treat LS-SCLC in actual practice across academic and community settings and analyze factors associated with fractionation and toxicity. Materials/Methods As part of a quality improvement initiative, the Michigan Radiation Oncology Quality Consortium prospectively collects clinical, dosimetric, and physician- and patient-reported outcomes data from patients treated for lung cancer at 29 institutions, which represent about 60% of the radiation oncology volume in the state. Between 2012 and 2021, 3,962 lung cancer cases were enrolled. Of those, 680 (17%) had SCLC histology and the 502 patients with LS-SCLC and known fractionation regimen represent the population studied here. Results Among the 502 LS-SCLC patients, 98% were current or former smokers (50 pack-year mean) and 98% received chemotherapy. In total, 73 (15%) were treated BID to a median dose of 45 Gy / 30 Fx (IQR same) and 429 (85%) were treated QD to a median dose of 60 Gy / 30 Fx (IQR 60-64.8 Gy / 30-36 Fx). The proportion of patients treated BID did not vary by practice setting or demographics except those treated BID were significantly more likely to be married or living with someone (64% vs 51%, p=0.035). There was no difference between the groups in baseline clinical factors such as performance status, weight loss, comorbidities, or pulmonary function. QD treated patients were more likely to experience a treatment break due to toxicity (24% vs 6%, p<0.01) despite no differences in physician-reported toxicity or patient-reported swallowing difficulty at the end of treatment. However, BID treated patients did report twice the rate of difficulty swallowing solids at 1 month (42% vs 19%, p<0.01). Conclusion Despite evidence in its favor, the twice-daily fractionation regimen for LS-SCLC remains infrequently prescribed (15%) in a large multicenter prospectively collected cohort. BID treated patients were more likely to be married or living with someone, perhaps relating to the logistic burden of BID treatment. Despite similar end of treatment toxicity, QD treated patients had more treatment breaks. However, BID treated patients had twice the rate of swallowing difficulty at 1 month suggesting BID toxicity may peak later than QD toxicity, which is consistent with prior reports. Analysis of late toxicity, chemotherapy specifics, and additional physician- and patient-reported outcomes is ongoing.





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