Is Occult Lymph Node Disease in Colorectal Cancer Patients Clinically Significant?

Abstract

The clinical significance of micrometastasis of colorectal cancer (CRC) to regional lymph nodes remains controversial. In this review, we analyze publications that have evaluated the clinical significance of occult lymph node metastasis in CRC. An extensive literature search identified 19 publications that evaluated the clinical significance of micrometastatic CRC by various methods, including immunohistochemistry (IHC; n ‫؍‬ 13) and reverse transcription-polymerase chain reaction (RT-PCR, n ‫؍‬ 6). These studies were reviewed for methodology and findings. Significant limitations in methodology were identified, including inconsistent histological definitions of micrometastatic disease, poor sampling because of an inadequate number of lymph nodes or number of sections per lymph node analyzed, lack of conformity with respect to IHC antibody or RT-PCR marker, and inadequate power because of small sample size. Micrometastatic lymph node metastasis identified by RT-PCR was consistently found to be prognostically significant, but this was not true of micrometastatic disease identified by IHC. RT-PCR analysis of lymph nodes with specific markers can help identify pN0 (pathological-negative lymph node) CRC patients at increased risk for recurrence. The identification of occult disease by IHC techniques may also ultimately prove to be associated with worse outcome, but a number of inadequately powered studies have concluded conversely.

Badanie metodą jednostopniowej amplifikacji kwasu nukleinowego węzłów chłonnych w raku brodawkowatym tarczycy — porównanie z badaniem histopatologicznym i badaniem PCR w czasie rzeczywistym

“…Today, the clinical staging according to the UICC classification depends on routine histopathological examination, which eventually is allied with immunohistochemistry. In other cancers, the situation is different [13,14]. We hope that introducing molecular methods will improve the assessment of PTC.…”

Molecular Testing for Lymph Node Metastases as a Determinant of Colon Cancer Recurrence: Results from a Retrospective Multicenter Study

“…Recently, multiple studies have demonstrated that there is an increased risk of recurrence associated with occult metastases in lymph node-negative colon cancer (7,24,25). In a systematic review with a cumulative sample size of 4,087 patients, Rahbari and colleagues reported that molecular detection of occult disease in regional nodes is associated with an increased risk of disease recurrence and poor survival in pN0 patients (25).…”

Molecular Staging Estimates Occult Tumor Burden in Colorectal Cancer

“…Although histopathology remains the standard paradigm, staging imprecision by conventional microscopy reflects methodological limitations [2,5,24]. Microscopic visualization is insensitive, with 7 a lower limit for detection of ~1 cancer cell in 200 normal cells [26].…”

“…Colorectal cancer causes ~10% of cancer-related deaths in the U.S., with a mortality rate approaching ~50% [1][2][3]. Mortality reflects metastases: ~20% of colorectal cancer patients have unresectable disease at presentation (stage IV) and >30% will develop metastases during the course of their disease [2][3][4][5]. Surgery continues to have the greatest impact on survival.…”