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<p>This study aimed to establish reference dose–volume parameters for various organs at risk (OARs) across clinically relevant dose-fractionation regimens in breast cancer radiotherapy. It further evaluated the variation in biologically effective doses (BEDs) of OARs as functions of different α/β values and fractionation schedules. The regimens examined include conventional (50&#xa0;Gy in 25 fractions), moderately hypofractionated (40&#xa0;Gy in 15 fractions), and ultrahypofractionated (27&#xa0;Gy–26&#xa0;Gy in 5 fractions) approaches. Left-sided breast (Br) or chest wall (CW) cancer, with or without supraclavicular fossa involvement, were planned using five-field intensity-modulated radiotherapy (IMRT). Evaluation parameters included heart D0.2&#xa0;cc, heart mean dose, and ipsilateral (left) lung mean dose. BEDs were calculated for six α/β values: 3.7, 3.0, 2.3, 2.0, 1.8, and 1.7&#xa0;Gy. Variations between prescribed and achieved doses, along with their corresponding BEDs, were analyzed using one-way ANOVA. This study included 359 patients, with 50 in the ultrahypofractionated group and 309 in the combined moderately hypofractionated and conventional group. For the 50&#xa0;Gy regimen, left lung mean BEDs ranged from 15.1 ± 4.2&#xa0;Gy to 21.4 ± 6.2&#xa0;Gy across different α/β values, suggesting potential risks of radiation pneumonitis or lung fibrosis. In contrast, the 26&#xa0;Gy regimen yielded lower mean BEDs, ranging from 8.4 ± 1.8&#xa0;Gy to 14.3 ± 3.3&#xa0;Gy, indicating a more favourable risk–benefit profile. For the heart, mean BEDs were 6.1 ± 2.1&#xa0;Gy to 8.6 ± 3.3&#xa0;Gy with 50&#xa0;Gy, compared with 3.3 ± 0.9&#xa0;Gy to 5.7 ± 1.5&#xa0;Gy with 26&#xa0;Gy. Heart D0.2&#xa0;cc BEDs were higher for 50&#xa0;Gy (69.6 ± 11.6&#xa0;Gy to 98.2 ± 15.8&#xa0;Gy) than for 26&#xa0;Gy (48.3 ± 11.7&#xa0;Gy to 81.4 ± 18.7&#xa0;Gy). All differences between prescription doses, OAR doses, and corresponding BEDs were statistically significant (<i>p</i> = 0.003–0.035). It is concluded that this study provided reference OAR dose–volume parameters and BED values across a range of α/β values for conventional, moderately hypofractionated, and ultrahypofractionated breast cancer radiotherapy in a large cohort of Asian women. Data presented here can guide treatment planning, support dose constraint selection, and aid interpretation of dosimetric data, particularly for ultrahypofractionated regimens, where evidence remains limited.</p>

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Characteristic variation of organs at risk dose and biologically effective dose as a function of different α/β values for conventional, moderate, and ultrahypofractionated breast cancer radiotherapy

  • 期刊论文

  • 发表日期：

    2025年11月15日

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  • Biplab Sarkar,
  • Anirudh Pradhan

摘要

This study aimed to establish reference dose–volume parameters for various organs at risk (OARs) across clinically relevant dose-fractionation regimens in breast cancer radiotherapy. It further evaluated the variation in biologically effective doses (BEDs) of OARs as functions of different α/β values and fractionation schedules. The regimens examined include conventional (50 Gy in 25 fractions), moderately hypofractionated (40 Gy in 15 fractions), and ultrahypofractionated (27 Gy–26 Gy in 5 fractions) approaches. Left-sided breast (Br) or chest wall (CW) cancer, with or without supraclavicular fossa involvement, were planned using five-field intensity-modulated radiotherapy (IMRT). Evaluation parameters included heart D0.2 cc, heart mean dose, and ipsilateral (left) lung mean dose. BEDs were calculated for six α/β values: 3.7, 3.0, 2.3, 2.0, 1.8, and 1.7 Gy. Variations between prescribed and achieved doses, along with their corresponding BEDs, were analyzed using one-way ANOVA. This study included 359 patients, with 50 in the ultrahypofractionated group and 309 in the combined moderately hypofractionated and conventional group. For the 50 Gy regimen, left lung mean BEDs ranged from 15.1 ± 4.2 Gy to 21.4 ± 6.2 Gy across different α/β values, suggesting potential risks of radiation pneumonitis or lung fibrosis. In contrast, the 26 Gy regimen yielded lower mean BEDs, ranging from 8.4 ± 1.8 Gy to 14.3 ± 3.3 Gy, indicating a more favourable risk–benefit profile. For the heart, mean BEDs were 6.1 ± 2.1 Gy to 8.6 ± 3.3 Gy with 50 Gy, compared with 3.3 ± 0.9 Gy to 5.7 ± 1.5 Gy with 26 Gy. Heart D0.2 cc BEDs were higher for 50 Gy (69.6 ± 11.6 Gy to 98.2 ± 15.8 Gy) than for 26 Gy (48.3 ± 11.7 Gy to 81.4 ± 18.7 Gy). All differences between prescription doses, OAR doses, and corresponding BEDs were statistically significant (p = 0.003–0.035). It is concluded that this study provided reference OAR dose–volume parameters and BED values across a range of α/β values for conventional, moderately hypofractionated, and ultrahypofractionated breast cancer radiotherapy in a large cohort of Asian women. Data presented here can guide treatment planning, support dose constraint selection, and aid interpretation of dosimetric data, particularly for ultrahypofractionated regimens, where evidence remains limited.