Introduction:
Treatment guidelines for colorectal cancer (CRC) suggest two classifications for histological differentiation—highest-grade and predominant. However, the optimal predictor of lymph node metastasis (LNM) in T1 CRC remains unknown. This systematic review aimed to evaluate the impact of the use of highest-grade or predominant differentiation on LNM determination in T1 CRC.
Methods:
The study protocol is registered in the International Prospective Register of Systematic Reviews (PROSPERO, registration number: CRD42023416971) and was published in OSF (https://osf.io/TMAUN/) on April 13, 2023.
We searched five electronic databases for studies assessing the diagnostic accuracy of highest-grade or predominant differentiation to determine LNM in T1 CRC. The outcomes were sensitivity and specificity. We simulated 100 T1 CRC cases, with an LNM incidence of 11.2%, to calculate the differences in false positives and negatives between the highest-grade and predominant differentiations using a bootstrap method.
Results:
In 42 studies involving 41,290 patients, the differentiation classification had a pooled sensitivity of 0.18 (95% confidence interval [CI], 0.13–0.24) and 0.06 (95% CI, 0.04–0.09) (P<0.0001) and specificity of 0.95 (95% CI, 0.93–0.96) and 0.98 (95% CI, 0.97–0.99) (P<0.0001) for the highest-grade and predominant differentiations, respectively. In the simulation, the differences in false positives and negatives between the highest-grade and predominant differentiations were 3.0% (range, 1.6–4.4) and −1.3% (range, −2.0 to −0.7), respectively.
Conclusions:
Highest-grade differentiation may reduce the risk of misclassifying LNM cases as negative, whereas predominant differentiation may prevent unnecessary surgeries. Further studies should examine differentiation classification using other predictive factors.