Sapienza Lucas Gomes, Maia Maria Aparecida Conte, Gomes Maria José Leite, Mattar André, Baiocchi Glauco, Calsavara Vinicius Fernando
Department of Radiation Oncology, Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA.
Department of Radiation Oncology, São Camilo Oncologia, São Paulo, SP, Brazil.
Clin Transl Radiat Oncol. 2022 Dec 21;39:100570. doi: 10.1016/j.ctro.2022.100570. eCollection 2023 Mar.
To assess the impact and optimize the prescription of tissue-equivalent bolus in postmastectomy radiotherapy (PMRT), we compared the use of different bolus regimens tailored by skin involvement status.
Patients with breast cancer who required PMRT were recruited (NCT01925651) and classified into two groups: standard-risk (SR, without skin involvement) and high-risk (HR, with skin involvement). SR was randomized between no bolus or 5 mm-bolus on alternate days and HR between 5 mm-bolus on alternate days or daily. Conventional fractionation (50.4 Gy; 1.8 Gy/daily) was used. Acute skin toxicity was evaluated blindly and the radiodermatitis-specific toxicity index [rads-TI] calculated. Subsequently, patients were followed up to assess oncologic outcomes, focusing on chest wall (CW) local control.
Fifty-eight patients were enrolled (34 SR and 24 HR). Baseline characteristics were similar between arms within the same risk group. Overall, maximal radiodermatitis rates were 29.4 % (G2) and 15.7 % (G3). In the SR group, no difference existed in G2 radiodermatitis incidence between the subgroups (p = 0.70) and no G3 events occurred. In the HR group, incidences of G2 (100 % vs 44.5 %, p = 0.01) and G3 radiodermatitis (70 % vs 11.1 %, p = 0.02) were higher with daily bolus. After adjusting for confounders, the daily bolus had a higher incidence of G2 (p = 0.03), G3 radiodermatitis (p = 0.04), and worse rads-TI (p < 0.01). After a median follow-up of 6.2 years, the 5-year local control was 95.8 % (95 %CI: 88.2 %-100 %) in the SR and 91.7 % (95 %CI: 77.3 %-100 %) in the HR groups. Per risk group, there was no difference in local control between the SR (p = 0.90) or the HR bolus regimens (p = 0.70).
Daily 5 mm bolus prescription significantly increased the overall toxicity burden. In this preliminary study, within the same risk group, no detriment in CW local control was detected with less intense bolus regimens (SR: no bolus; HR: alternate-days bolus). Additionally, the rads-TI was able to distinguish overall radiodermatitis burden.
为评估组织等效填充物在乳房切除术后放疗（PMRT）中的影响并优化其处方，我们比较了根据皮肤受累状况定制的不同填充物方案的使用情况。
招募需要进行PMRT的乳腺癌患者（NCT01925651），并将其分为两组：标准风险组（SR，无皮肤受累）和高风险组（HR，有皮肤受累）。SR组在不使用填充物或隔天使用5毫米填充物之间随机分配，HR组在隔天使用5毫米填充物或每天使用之间随机分配。采用常规分割放疗（50.4 Gy；每日1.8 Gy）。对急性皮肤毒性进行盲法评估，并计算放射性皮炎特异性毒性指数[rads-TI]。随后，对患者进行随访以评估肿瘤学结局，重点关注胸壁（CW）局部控制情况。
共纳入58例患者（34例SR组和24例HR组）。同一风险组内各亚组的基线特征相似。总体而言，最大放射性皮炎发生率为29.4%（2级）和15.7%（3级）。在SR组中，各亚组之间2级放射性皮炎发生率无差异（p = 0.70），且未发生3级事件。在HR组中，每日使用填充物时2级（100%对44.5%，p = 0.01）和3级放射性皮炎的发生率（70%对11.1%，p = 0.02）更高。在对混杂因素进行校正后，每日使用填充物时2级（p = 0.03）、3级放射性皮炎（p = 0.04）的发生率更高，且rads-TI更差（p < 0.01）。中位随访6.2年后，SR组的5年局部控制率为95.8%（95%CI：88.2% - 100%），HR组为91.7%（95%CI：77.3% - 100%）。按风险组划分，SR组（p = 0.90）或HR组填充物方案之间的局部控制率无差异（p = 0.70）。
每日5毫米填充物处方显著增加了总体毒性负担。在这项初步研究中，在同一风险组内，强度较低的填充物方案（SR组：不使用填充物；HR组：隔天使用填充物）未检测到对CW局部控制有不利影响。此外，rads-TI能够区分总体放射性皮炎负担。
