Palliative radiotherapy for bone metastases at the end of life in Victoria

Effects of ultra-high dose rate radiotherapy with different fractions and dose rate on acute and chronic lung injury in mice

Ultra-high dose rate radiotherapy (FLASH radiation) can naturally render normal tissues around the tumor tissue resistant to radiotherapy. In contrast, the tumor tissue remains sensitive to radiation under the same conditions. However, the effects of different fractions and dose rates on FLASH radiation remain unclear. This study aimed to determine the optimal dose rate and fraction of FLASH radiation for thoracic radiotherapy. Female Balb/c mice aged 6-8 weeks were irradiated with different dose rates (100 Gy/s or 250 Gy/s) and fractions (1, 2, or 4). Survival was observed in mice receiving 30Gy, with lung tissue examined for acute radiation damage 48 h post-radiation. Late radiation pneumonia and survival rates were monitored in mice irradiated with 20 Gy. The median overall survival (OS) was not reached on the 95th day for mice irradiated with 250 Gy/s FLASH radiation, while it was 89.5 days for those irradiated with 100 Gy/s (P = 0.0436). Mice irradiated with 30 Gy/2 Fr and 250 Gy/s FLASH had shorter median OS than those with 30 Gy/1F (P = 0.0132). However, there was no significant difference in OS between mice irradiated with 30 Gy/2 F and 30 Gy/4 F. Survival curves for mice receiving 20 Gy showed no significant difference in toxicity between different dose rates and fractions. FLASH radiation at 250 Gy/s reduced the incidence of acute radiation pneumonitis in mice compared to 100 Gy/s. Different fractions of irradiation influenced survival in mice, but they were only observed in acute radiation reactions and not chronic radiation reactions. Among the tested fraction methods, fraction 2 had the worst impact on the survival of mice, while fractions 1 and 4 showed similar effects and improved survival compared to fraction 2.

Large variation in radiation therapy fractionation for multiple myeloma in Australia

AIM

To evaluate the patterns of use of different radiation therapy (RT) fractionation for multiple myeloma (MM) bone disease.

METHODS

This is a population-based cohort of patients with MM who had RT between 2012 and 2017 as captured in the statewide Victorian Radiotherapy Minimum Data Set in Australia. Data linkage was performed to identify subsets of RT delivered within 3 months of death. RT fractionation was classified into four groups: single-fraction (SFRT), 2-5, 6-10, and > 10 fractions. Changes in RT fractionation use over time were evaluated with the Cochran-Armitage test for trend. Factors associated with RT fractionation were evaluated using multivariate logistic regressions.

RESULTS

Nine hundred and sixty-seven courses of RT were delivered in 623 patients. The proportion of SFRT, 2-5, 6-10 and > 10 fractions RT was 18%, 47%, 28%, and 7%, respectively. There was an increase in the use of 2-5 fractions, from 48% in 2012 to 60% in 2017 (p-trend < .001), with corresponding decrease in the use of 6-10 fractions, from 26% in 2012 to 20% in 2017 (p-trend = .003). Nine percent (40/430) of RT courses at private institutions were SFRT, compared to 25% (135/537) in public institutions (p < .001). In multivariate analyses, treatment in private institution was the strongest predictor of multifraction RT use. SFRT use was more common closer to the end of life-18%, 14%, and 33% of RT within 2-3, 1-2, < 1 month of death, respectively.

CONCLUSION

There is increasing use of shorter course RT (2-5 fractions) for MM over time. SFRT use remains low, with large variation in practice.

Evolving Practice Pattern of Palliative Radiation Therapy for Bone Metastases from Lung Cancer in Australia

AIMS

Radiation therapy is an effective treatment for bone metastases. Single-fraction conformal radiation therapy (SF-CRT) is equally effective as multifraction radiation therapy for the management of uncomplicated bone metastases. There has been a rapid development of advanced radiation therapy techniques (ART) in radiation oncology. We evaluated the changing pattern of SF-CRT and ART use for the management of bone metastases in lung cancer.

MATERIALS AND METHODS

This was a state-wide population-based cohort of lung cancer patients from Victoria, Australia, who received radiation therapy for bone metastases between 2012 and 2017. The primary outcomes were proportion of radiation therapy courses using: SF-CRT and ART. We identified a subcohort in which radiation therapy was delivered at the end of life (EOL), i.e. within 30 days of death. The Cochran-Armitage test for trend was used to evaluate the change in pattern of SF-CRT and ART use over time. Multivariable analyses were used to identify factors associated with the primary outcomes.

RESULTS

Of the 4335 courses of radiation therapy for bone metastases in lung cancer, 20% were SF-CRT - increasing from 19% in 2012 to 26% in 2017 (P-trend = 0.004). In multivariate analyses, treatment to the rib, shoulder, hip or extremities, and treatment in public institutions were independently associated with SF-CRT use, but the effect of year of radiation therapy was no longer significant. Five per cent of radiation therapy was delivered using ART, increasing markedly from 2016 onwards (P-trend < 0.001). In multivariate analyses, treatment in private institutions and more recent years of treatment were independently associated with the use of ART. There were 587 courses of radiation therapy delivered at the EOL, with SF-CRT more commonly used closer to death - 53%, 29% and 25% of radiation therapy within 7 days, 8-14 days and 15-30 days of death, respectively.

CONCLUSION

SF-CRT continued to be underutilised for bone metastases in lung cancer in Australia, including at the EOL. We observed an increase in ART use for bone metastases from 2016, which occurred contemporaneously with changes in government funding.