Department of Pathology, University of California, San Francisco, San Francisco, CA, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA; Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Department of Pathology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania.
Lancet Oncol. 2024 Nov;25(11):1440-1452. doi: 10.1016/S1470-2045(24)00456-X. Epub 2024 Oct 3.
Use of fine-needle aspiration biopsy (FNAB) specimens on Xpert Breast Cancer STRAT4 Assay (STRAT4; Cepheid, Sunnyvale, CA, USA), a CE-marked in-vitro diagnostic medical device, could potentially increase access to breast cancer biomarker testing in resource-constrained settings. We aimed to assess the performance of a research use-only version of STRAT4 using FNAB specimens in Tanzania.
In this prospective diagnostic accuracy study, patients aged 18 years or older with palpable breast masses presenting to the FNAB Clinic at Muhimbili National Hospital (Dar es Salaam, Tanzania) were recruited consecutively. Patients who were pregnant, lactating, or had a previous diagnosis of breast cancer were excluded. STRAT4 testing was performed on off-label FNAB samples using four protocols: the 1 × protocol (using the standard lysate method) on FNAB smears (1 × FNAB), quick lysis and Maui protocols (both on FNAB smears), and the 1 × protocol on formalin-fixed paraffin-embedded (FFPE) cell block material (1 × cell block). For 1 × FNAB and 1 × cell block, tissue was processed using FFPE lysis reagent, incubated at 80°C with proteinase K, and followed by addition of 95% or higher ethanol. Quick lysis was processed using FFPE lysis reagent and 95% or higher ethanol, whereas Maui was processed using a proprietary research-use only lysis reagent. The primary outcomes were overall concordance, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of STRAT4 as compared with immunohistochemistry or immunohistochemistry plus fluorescence in-situ hybridisation performed on cell blocks using clinically validated protocols in a Clinical Laboratory Improvement Amendments-accredited laboratory at the University of California, San Francisco (San Francisco, CA, USA).
Between Nov 29, 2017, and Dec 17, 2020, 208 patients were enrolled. Of 208 cases, 51 (25%) were excluded from analysis because of insufficient tissue in the cell block or absent cell blocks, leaving 157 participants (all female) for analysis. For oestrogen receptor, 1 × FNAB had the best performance, with an overall concordance of 95% (95% CI 90-100), sensitivity of 94% (85-100), specificity of 97% (90-100), and AUC of 0·96 (0·81-1·00). For progesterone receptor, 1 × cell block had the best overall performance (overall concordance 89% [95% CI 84-95], sensitivity 91% [82-99], and specificity 89% [81-97], with an AUC of 0·93 [0·89-0·99]) and 1 × FNAB performed the best among the smear protocols, with a concordance of 84% (95% CI 74-93), sensitivity of 63% (43-82), specificity of 97% (92-100), and AUC of 0·91 (0·72-0·97). For HER2, Maui had the highest agreement, with an overall concordance of 93% (95% CI 89-98), sensitivity of 96% (88-100), specificity of 92% (87-98), and AUC of 0·95 (0·98-1·00). For Ki67, Maui had the best performance of smear protocols, with a concordance of 73% (95% CI 64-82), sensitivity of 70% (58-81), specificity of 81% (66-96), and AUC of 0·80 (0·54-0·82).
Processing FNAB samples with STRAT4 is feasible in Tanzania, and performance for the oestrogen receptor is robust. Further optimisation of STRAT4 for FNAB has the potential to improve timely access to breast cancer diagnostics in resource-constrained settings.
US National Institutes of Health; UCSF Global Cancer Program, Helen Diller Family Comprehensive Cancer Center; UCSF Department of Pathology; and Cepheid.
STRAT4 检测（STRAT4；Cepheid，加利福尼亚州森尼韦尔）是一种经过 CE 标记的体外诊断医疗器械，利用细针穿刺抽吸活检（FNAB）标本进行检测，有可能增加资源有限环境下进行乳腺癌生物标志物检测的机会。我们的目的是评估 STRAT4 的研究专用版本在坦桑尼亚使用 FNAB 标本的性能。
这是一项前瞻性诊断准确性研究，连续纳入了 18 岁或以上，有可触及乳腺肿块，且于穆希比利国家医院（坦桑尼亚达累斯萨拉姆） FNAB 诊所就诊的患者。妊娠、哺乳期或有乳腺癌既往诊断的患者被排除在外。使用四种方案在研究专用的 STRAT4 上对 FNAB 标本进行检测：标准裂解液法的 1×方案（1×FNAB）用于 FNAB 涂片，快速裂解和 Maui 方案（均用于 FNAB 涂片），以及甲醛固定石蜡包埋（FFPE）细胞块材料的 1×方案（1×细胞块）。对于 1×FNAB 和 1×细胞块，组织使用 FFPE 裂解试剂处理，在 80°C 下与蛋白酶 K孵育，然后加入 95%或更高浓度的乙醇。快速裂解使用 FFPE 裂解试剂和 95%或更高浓度的乙醇，而 Maui 使用专有研究专用的裂解试剂。主要结局指标是与加利福尼亚大学旧金山分校（旧金山，加利福尼亚州）临床实验室改进修正案认证实验室中使用临床验证方案在细胞块上进行的免疫组织化学或免疫组织化学加荧光原位杂交相比，STRAT4 的总体一致性、敏感性、特异性和接受者操作特征曲线（ROC）下面积（AUC）。
2017 年 11 月 29 日至 2020 年 12 月 17 日期间，共纳入 208 例患者。由于细胞块中组织不足或不存在细胞块，51 例（25%）患者被排除在分析之外，剩余 157 名（均为女性）参与者进行了分析。对于雌激素受体，1×FNAB 的表现最佳，总体一致性为 95%（95%CI 90-100），敏感性为 94%（85-100），特异性为 97%（90-100），AUC 为 0.96（0.81-1.00）。对于孕激素受体，1×细胞块的总体性能最佳（总体一致性为 89%（95%CI 84-95），敏感性为 91%（82-99），特异性为 89%（81-97%），AUC 为 0.93（0.89-0.99）），1×FNAB 在涂片方案中表现最佳，一致性为 84%（95%CI 74-93），敏感性为 63%（43-82），特异性为 97%（92-100），AUC 为 0.91（0.72-0.97）。对于 HER2，Maui 的一致性最高，总体一致性为 93%（95%CI 89-98），敏感性为 96%（88-100），特异性为 92%（87-98），AUC 为 0.95（0.98-1.00）。对于 Ki67，Maui 在涂片方案中的表现最佳，一致性为 73%（95%CI 64-82），敏感性为 70%（58-81），特异性为 81%（66-96），AUC 为 0.80（0.54-0.82）。
在坦桑尼亚，使用 STRAT4 处理 FNAB 标本是可行的，雌激素受体的性能可靠。进一步优化 STRAT4 用于 FNAB 有可能改善资源有限环境下乳腺癌诊断的及时性。
美国国立卫生研究院；加州大学旧金山分校全球癌症计划，海伦·迪勒家庭综合癌症中心；加州大学旧金山分校病理学系；和 Cepheid。
