Ahmanson Translational Imaging Division, Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, California.
Department of Radiation Oncology, UCLA, Los Angeles, California.
J Nucl Med. 2018 Nov;59(11):1714-1721. doi: 10.2967/jnumed.118.209387. Epub 2018 Apr 13.
Standard-of-care imaging for initial staging of prostate cancer (PCa) underestimates disease burden. Prostate-specific membrane antigen (PSMA) PET/CT detects PCa metastasis with superior accuracy, having a potential impact on the planning of definitive radiation therapy (RT) for nonmetastatic PCa. Our objectives were to determine how often definitive RT planning based on standard target volumes covers Ga-PSMA-11 PET/CT-defined disease and to assess the potential impact of Ga-PSMA-11 PET/CT on definitive RT planning. This was a post hoc analysis of an intention-to-treat population of 73 patients with localized PCa without prior local therapy who underwent Ga-PSMA PET/CT for initial staging as part of an investigational new drug trial. Eleven of the 73 were intermediate-risk (15%), 33 were high-risk (45%), 22 were very-high-risk (30%), and 7 were N1 (9.5%). Clinical target volumes (CTVs), which included the prostate, seminal vesicles, and (in accord with the Radiation Therapy Oncology Group consensus guidelines) pelvic lymph nodes (LNs), were contoured on the CT portion of the PET/CT images by a radiation oncologist masked to the PET findings. Ga-PSMA-11 PET/CT images were analyzed by a nuclear medicine physician. Ga-PSMA-11-positive lesions not covered by planning volumes based on the CTVs were considered to have a major potential impact on treatment planning. All patients had one or more Ga-PSMA-11-positive primary prostate lesions. Twenty-five (34%) and 7 (9.5%) of the 73 patients had Ga-PSMA-11-positive pelvic LN and distant metastases, respectively. The sites of LN metastases in decreasing order of frequency were external iliac (20.5%), common iliac (13.5%), internal iliac (12.5%) obturator (12.5%), perirectal (4%), abdominal (4%), upper diaphragm (4%), and presacral (1.5%). The median size of the LN lesions was 6 mm (range, 4-24 mm). RT planning based on the CTVs covered 69 (94.5%) of the 73 primary lesions and 20 (80%) of the 25 pelvic LN lesions, on a per-patient analysis. Ga-PSMA-11 PET/CT had a major impact on intended definitive RT planning for PCa in 12 (16.5%) of the 73 patients whose RT fields covered the prostate, seminal vesicles, and pelvic LNs and in 25 (37%) of the 66 patients whose RT fields covered the prostate and seminal vesicles but not the pelvic LNs.
对于前列腺癌（PCa）的初始分期，标准的影像学检查低估了疾病的负担。前列腺特异性膜抗原（PSMA）PET/CT 以更高的准确性检测 PCa 转移，这可能会对非转移性 PCa 的确定性放射治疗（RT）计划产生影响。我们的目的是确定基于标准靶区的确定性 RT 计划覆盖 Ga-PSMA-11 PET/CT 定义的疾病的频率，并评估 Ga-PSMA-11 PET/CT 对确定性 RT 计划的潜在影响。这是一项意向治疗人群的事后分析，共纳入 73 例未接受过局部治疗的局限性 PCa 患者，这些患者接受 Ga-PSMA PET/CT 进行初始分期，作为一项新药试验的一部分。73 例患者中，11 例为中危（15%），33 例为高危（45%），22 例为极高危（30%），7 例为 N1（9.5%）。临床靶区（CTV）包括前列腺、精囊和（根据放射治疗肿瘤学组共识指南）盆腔淋巴结（LN），由一位放射肿瘤学家在 PET/CT 图像的 CT 部分进行勾画，该医生对 PET 结果不知情。Ga-PSMA-11 PET/CT 图像由核医学医师进行分析。未被基于 CTV 的计划体积覆盖的 Ga-PSMA-11 阳性病变被认为对治疗计划有重大潜在影响。所有患者均有一个或多个 Ga-PSMA-11 阳性原发性前列腺病变。25 例（34%）和 7 例（9.5%）患者的盆腔 LN 和远处转移存在 Ga-PSMA-11 阳性。LN 转移部位的频率依次为髂外（20.5%）、髂总（13.5%）、髂内（12.5%）、闭孔（12.5%）、直肠周围（4%）、腹部（4%）、上膈（4%）和骶前（1.5%）。LN 病变的中位大小为 6mm（范围，4-24mm）。基于 CTV 的 RT 计划覆盖了 73 例患者中的 69 例（94.5%）和 25 例患者中的 20 例（80%），进行了患者层面的分析。Ga-PSMA-11 PET/CT 在 73 例接受 RT 治疗前列腺、精囊和盆腔 LN 的患者中，有 12 例（16.5%）和在 66 例仅接受 RT 治疗前列腺和精囊而不治疗盆腔 LN 的患者中，有 25 例（37%）的患者中对 RT 计划具有重大影响。
