Department of Urology, Vita Salute San Raffaele University, Milan, Italy.
Int J Radiat Oncol Biol Phys. 2012 Jun 1;83(2):624-9. doi: 10.1016/j.ijrobp.2011.06.2014. Epub 2011 Nov 16.
Previous studies have criticized the predicting ability of the Roach formula in assessing the risk of lymph node invasion (LNI) in contemporary patients with prostate cancer (PCa) due to a significant overestimation of LNI rates. However, all those studies included patients treated with limited pelvic lymph node dissection (PLND), which is associated with high rates of false negative findings. We hypothesized that the Roach formula is still an accurate tool for LNI predictions if an extended PLND (ePLND) is performed.
We included 3,115 consecutive patients treated with radical prostatectomy and ePLND between 2000 and 2010 at a single tertiary referral center. Extended PLND consisted of removal of obturator, external iliac, and hypogastric lymph nodes. We externally validated the Roach formula by using the area under the receiver operating characteristics curve and calibration plot method. Moreover, we tested the performance characteristics of different formula-generated cutoff values ranging from 1% to 20%.
The accuracy of the Roach formula was 80.3%. The calibration showed only a minor underestimation of the LNI risk in high-risk patients (6.7%). According to the Roach formula, the use of 15% cut off would have allowed 74.2% (2,311/3,115) of patients to avoid nodal irradiation, while up to 32.7% (111/336) of all patients with LNI would have been missed. When the cut off was lowered to 6%, nodal treatment would have been spared in 1,541 (49.5%) patients while missing 41 LNI patients. The sensitivity, specificity, and negative predictive values associated with the 6% cut off were 87.9%, 54%, and 97.3%, respectively.
The Roach formula is still accurate and does not overestimate the rate of LNI in contemporary prostate cancer patients if they are treated with ePLND. However, the recommended cut off of 15% would miss approximately one-third of patients with LNI. Based on our results, the cut off should be lowered to 6%.
先前的研究批评了 Roach 公式在评估当代前列腺癌（PCa）患者淋巴结侵犯（LNI）风险方面的预测能力，因为它对 LNI 发生率的高估显著。然而，所有这些研究都包括接受有限盆腔淋巴结清扫术（PLND）治疗的患者，这与较高的假阴性发现率相关。我们假设，如果进行广泛的 PLND（ePLND），Roach 公式仍然是 LNI 预测的准确工具。
我们纳入了 2000 年至 2010 年在一家单一的三级转诊中心接受根治性前列腺切除术和 ePLND 的 3115 例连续患者。广泛的 PLND 包括切除闭孔、外髂和腹下淋巴结。我们通过接受者操作特征曲线下面积和校准图方法对外验证 Roach 公式。此外，我们测试了不同公式生成的截止值范围从 1%到 20%的性能特征。
Roach 公式的准确性为 80.3%。校准结果显示，高危患者的 LNI 风险仅略有低估（6.7%）。根据 Roach 公式，使用 15%的截止值将允许 74.2%（2311/3115）的患者避免淋巴结照射，而高达 32.7%（111/336）的所有 LNI 患者将被遗漏。当截止值降低到 6%时，将有 1541 名（49.5%）患者避免淋巴结治疗，而遗漏 41 名 LNI 患者。与 6%截止值相关的敏感性、特异性和阴性预测值分别为 87.9%、54%和 97.3%。
如果对接受 ePLND 的当代前列腺癌患者使用 Roach 公式，该公式仍然准确，并且不会高估 LNI 发生率。然而，建议的 15%截止值将遗漏大约三分之一的 LNI 患者。基于我们的结果，截止值应降低到 6%。
