Lymph node micrometastasis and survival of patients with Stage I (Dukes' A) colorectal carcinoma

Objective. Although patients with Stage I colorectal cancer show an excellent prognosis, a few of them die of metastatic disease. In this subgroup of individuals, the search of occult metastasis might reveal that early dissemination of tumor cells could be the cause of cancer progression. Material and methods. Through a Cancer Registry, we selected all patients with Stage I disease who died of metastatic tumor; a total of 32 patients were identified and in 25 of them paraffin-embedded material was available. The group was matched to 70 Stage I patients with favorable prognosis (controls). In cases and controls resected lymph nodes were cut, and micrometastases were searched using pan-cytokeratin antibodies. Results. Micrometastases were detected in 18 of 25 (72%) Stage I patients who died of the disease, while they were almost absent among controls (1 of 70, p < 0.001 by X(2) test). Vascular invasion and tumor budding were more frequent among Stage I patients with an unfavorable prognosis than in controls. By regression analyses, micrometastases (HR 12.3, CI 4.8-32) and vascular invasion (HR 3.5, CI 1.4-8.5) maintained an independent association with prognosis (cancer-specific survival). Conclusion. Micrometastasis in the lymph nodes can be revealed in the majority of patients with early colorectal cancer who die of tumor progression, while they appear extremely rare in Stage I individuals with good prognosis. The selection of patients through histology (vascular invasion) and search of occult metastatic cells might represent a way to identify individuals who might benefit from adjuvant chemotherapy.