Department of Surgery, Beth Israel Deaconess Medical Center, Boston, MA, USA.
Department of Surgery, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.
J Gastrointest Surg. 2019 Apr;23(4):794-799. doi: 10.1007/s11605-019-04119-x. Epub 2019 Feb 4.
Pathologic complete response (pCR) is associated with better prognosis and guides management for patients with advanced rectal cancer. Response rates vary between series for unclear reasons. We examine whether the thoroughness of pathologic assessment explains differences in pCR rates.
We retrospectively reviewed pathology reports from patients with stage II/III rectal cancer who underwent chemoradiation and resection in a prospective, multicenter trial. We utilized a novel measure for the thoroughness of pathologic assessment by dividing residual tumor size by the number of cassettes evaluated (tumor size to cassette ratio, TSCR), and evaluated whether TSCR is associated with pCR. We validated our findings using a separate cohort.
From the trial cohort, 71 of 247 (29%) patients achieved pCR. The pCR rate ranged from 0 to 45% and mean TSCR ranged 0.29 to 0.87 across 12 institutions. Within each institution, a lower TSCR was associated with pCR, demonstrating a higher degree of thoroughness used for tumors that achieved pCR. Moreover, across all samples, low TSCR was independently associated with pCR on multivariable analysis. This finding was corroborated in a separate cohort of 201 tumors evaluated by five pathologists; each pathologist had a lower mean TSCR for pCR calls compared with non-pCR calls. However, the mean TSCR for an institution was not associated with its overall pCR rate.
Pathologists assess rectal cancers that have responded significantly to neoadjuvant therapy more thoroughly. Thoroughness does not appear to explain differences in pCR rates between institutions. Our results suggest pCR is not a sampling artifact.
病理完全缓解（pCR）与更好的预后相关，并指导局部晚期直肠癌患者的管理。由于原因不明，各系列之间的反应率存在差异。我们研究病理评估的彻底性是否可以解释 pCR 率的差异。
我们回顾性分析了在一项前瞻性多中心试验中接受放化疗和切除术的 II/III 期直肠癌患者的病理报告。我们利用一种新的方法来评估病理评估的彻底性，即将残余肿瘤大小除以评估的标本数量（肿瘤大小与标本数量之比，TSCR），并评估 TSCR 是否与 pCR 相关。我们使用单独的队列验证了我们的发现。
在试验队列中，247 例患者中有 71 例（29%）达到了 pCR。pCR 率范围为 0 至 45%，12 个机构的平均 TSCR 范围为 0.29 至 0.87。在每个机构内，较低的 TSCR 与 pCR 相关，这表明对达到 pCR 的肿瘤进行了更高程度的彻底评估。此外，在所有样本中，多变量分析显示低 TSCR 与 pCR 独立相关。这一发现在由五名病理学家评估的 201 个肿瘤的单独队列中得到了证实；与非 pCR 相比，每位病理学家对 pCR 报告的平均 TSCR 较低。然而，机构的平均 TSCR 与总体 pCR 率无关。
病理学家对新辅助治疗后反应明显的直肠癌进行更彻底的评估。彻底性似乎不能解释机构之间 pCR 率的差异。我们的结果表明 pCR 不是抽样误差。
