Purpose

Randomized data support accelerated partial breast irradiation (APBI) for early-stage breast cancer with variable techniques and cosmesis outcomes. We have treated patients with 5-fraction prone external beam APBI for over a decade and herein report acute and late outcomes.

Methods and Materials

Patients receiving APBI 600 cGy × 5 between 2010 and 2019 were included. APBI was primarily delivered prone, with opposed tangents targeting the tumor bed expanded by 1.5 cm (cropped 6 mm from skin). Ipsilateral breast was constrained to V50% < 60% and V100% < 35%. Survival was estimated with Kaplan-Meier. Late toxicities and clinician- and patient-rated cosmesis were evaluated for patients with >6 months follow-up (FU).

Results

Of 345 patients meeting criteria, 14 were excluded due to APBI given for ipsilateral breast tumor recurrence (IBTR; n = 3), palliation (n = 9), and incomplete radiation therapy course (n = 2). Of the 331 remaining, median age was 70, 7.2% had ductal carcinoma in situ, and 94.3% were treated prone, with 32% treated every other day and 68% on consecutive days. Mean heart dose was 23.8 cGy for left-sided and 12.7 cGy for right-sided cancers. Ipsilateral lung V30% was 0.4%. At 5-year median FU, there were 7 (2.1%) IBTR, 9 (2.7%) contralateral recurrences, and 1 (0.3%) distant metastasis. Five-year local recurrence-free, disease-free, and overall survival was 99.5%, 96.7%, and 98.1%, respectively. When comparing patients with IBTR versus without, a higher proportion did not receive hormone therapy (71.4% vs. 26.2%, P = .018). Rates of acute grade 1 to 2 dermatitis, fatigue, and pain were 35.4%, 21.8%, and 9.4%, respectively, with no grade 3 toxicity. The rate of good-excellent physician- and patient-rated cosmesis (n = 199, median FU 2.8 years) was 92.5% and 89.4%, respectively. Patients experienced low rates of telangiectasia, fibrosis, and retraction/atrophy.

Conclusions

We report excellent dosimetric, oncologic, cosmetic, and late toxicity outcomes for patients treated with 5-fraction APBI. To our knowledge this is the largest series of women treated with prone APBI.

中文翻译：

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5 分数俯卧加速部分乳房照射：长期肿瘤学、剂量学和美容结果

目的

随机数据支持早期乳腺癌的加速部分乳房照射（APBI），具有可变的技术和美容效果。十多年来，我们已经治疗了 5 次俯卧外束 APBI 患者，并在此报告了急性和晚期结果。

方法和材料

纳入 2010 年至 2019 年间接受 APBI 600 cGy × 5 的患者。APBI 主要采用俯卧位给药，针对肿瘤床的相对切线扩大了 1.5 厘米（距皮肤 6 毫米）。同侧乳房受限于 V50% < 60% 和 V100% < 35%。使用 Kaplan-Meier 估计存活率。对随访时间 > 6 个月 (FU) 的患者评估晚期毒性以及临床医生和患者评定的美容效果。

结果

在符合标准的 345 名患者中，14 名因同侧乳腺肿瘤复发（IBTR；n = 3）、姑息治疗（n = 9）和不完整的放射治疗过程（n = 2）而被排除在外。在剩下的 331 人中，中位年龄为 70 岁，7.2% 患有导管原位癌，94.3% 接受俯卧治疗，32% 隔日治疗，68% 连续治疗。左侧癌症的平均心脏剂量为 23.8 cGy，右侧癌症的平均心脏剂量为 12.7 cGy。同侧肺 V30% 为 0.4%。在 5 年中位 FU 时，IBTR 7 例（2.1%），对侧复发 9 例（2.7%），远处转移 1 例（0.3%）。五年局部无复发、无病和总生存率分别为 99.5%、96.7% 和 98.1%。在比较接受 IBTR 与未接受 IBTR 的患者时，更高比例的患者未接受激素治疗（71.4% vs. 26.2%，P = .018)。急性 1 至 2 级皮炎、疲劳和疼痛的发生率分别为 35.4%、21.8% 和 9.4%，无 3 级毒性。优秀医师和患者评价的美容（n = 199，中位 FU 2.8 年）分别为 92.5% 和 89.4%。患者毛细血管扩张、纤维化和收缩/萎缩的发生率较低。

结论

我们报告了接受 5 分数 APBI 治疗的患者的剂量学、肿瘤学、美容和晚期毒性结果。据我们所知，这是接受俯卧 APBI 治疗的最大系列女性。