Year : 2019 | Volume
: 62 | Issue : 2 | Page : 197--198
Prognostic value of lymph node ratio in cancer
Department of Pathology, S.C.B. Medical College, Cuttack, Odisha, India
Department of Pathology, S.C.B. Medical College, Cuttack, Odisha
|How to cite this article:|
Kar A. Prognostic value of lymph node ratio in cancer.Indian J Pathol Microbiol 2019;62:197-198
|How to cite this URL:|
Kar A. Prognostic value of lymph node ratio in cancer. Indian J Pathol Microbiol [serial online] 2019 [cited 2019 Jul 16 ];62:197-198
Available from: http://www.ijpmonline.org/text.asp?2019/62/2/197/255802
The status of regional lymph node metastasis (LNM) has been widely considered as an important prognostic factor to plan subsequent postoperative management of patients with cancer. Although LNM is a simple, convenient, and reliable method for precise staging, the identified number of metastatic LNs depends on the number of dissected LNs. A low number of examined LNs may lead to false understaging and subsequent underestimation of cancer spread. This phenomenon is referred to as stage migration. There is also disparity regarding the number of LNs to be resected. Lymph node ratio (LNR) is defined as the ratio of number of positive LNs or LNM to total nodes removed or harvested (LNH) and is used as an important prognostic factor. Draining LNs of a tumor may enlarge due to metastasis or reactive hyperplasia and frequently they can coexist. Till date, tumor node metastasis (TNM) staging is the commonly applied tool to determine the stage of cancer, overall survival, and disease-free survival. However, there are no definite criteria to clarify about the optimum number of LNs necessary to determine the stage of cancer. Recent studies have suggested that LNR is more accurate in predicting overall survival and recurrence-free survival rate compared to the number of positive nodes alone.,, It is considered an important prognostic factor in malignancies of gastrointestinal tract, breast, bladder, and pancreas. LNR has been categorized into four groups according to Kaplan-Meier plots into LNR1 0–12%, LNR2 13–40%, LNR3 41–84%, and LNR4 85–100%. Survival rate for the four groups were found 57.9%, 78.6%, 17.6%, and 12.5% and disease-free survival rate were 52.6%, 42.9%, 17.6%, and 18.8%, respectively. With the increase in LNR, disease-free survival decreases except LNR4, similar to LNR3 with significant P value of 0.009.
The evaluation of LNR with tumor stage, tumor grade, LN reactive patterns, and LN size has been done in a recent publication of this journal, where primary malignancies of different organs such as breast, gastrointestinal tract, genitourinary tract, head, face, neck, and thyroid were analyzed. LN reactive pattern has been categorized into six morphological patterns out of which sinus histiocytosis and follicular hyperplasia are the most common patterns irrespective of nodal metastases. However, thickened capsule is a very useful clue for determining metastasis with significant P value.
Higher predictive value has been observed with LNR than lymph node stage. Breast carcinoma was classified as low risk (LNR 0.01–0.2), intermediate risk (LNR 0.21–0.65), and high risk (LNR 0.66–1.0) with the 5 year survival being 66.7%, 50%, and 0.0%, respectively. Higher LNR was observed in index study possibly because of lowest LNH yield as also related to majority cases being in stage T3. Higher LNR (12.6–25%) was found to be associated with higher risk of death in the study done by Wright et al. LNR cut-off value can be different in malignancies of different organs, which needs further evaluation and standardization. Head and neck cancers have been categorized as low LNR <0.06, medium 0.06–0.17, and high LNR >0.17 in previous studies. In that study, patients with low LNR were found to have longer 3 year survival and metastasisfree survival and 71.7% cases were seen in stage T4 and LNM was 53.8%. Studies found 49.5% LNM in nodes <0.5 cm size and 25% in >1.0 cm size of colon cancers. However, in oral cancers, mean size of positive nodes was found to be 0.3 cm by other authors. In the contrary, in the present study, metastasis was observed in small LNs up to 0.4 cm, whereas even LNs up to 3.0 cm showed nonmetastatic reactive hyperplasia. Above all, LNR showed stronger relation with tumor grade than with tumor stage. High LNR was also correlated with the higher risk of multiple metastasis locations and had worse response to chemotherapy.
LNR is a better prognostic marker in comparison to LN staging of TNM classification. The routine inclusion of LNR and LN reactive patterns in tumor reporting by pathologists may become a prognostic aid for clinicians along with TNM staging system. This can predict relapse and survival of cancer patients more closely. LNH and LNR cutoff values show organwise variation, hence need standardization before their usage in cancer staging systems. Use of immunohistochemistry, nucleic acid amplification, and the polymerase chain reaction can further aid in detecting minute nodal metastases.
LNR can be adopted in follow-up of various cancers because of its simplicity and reproducibility. In spite of several studies on epithelial malignancies, no unified and well-recognized optimal cut-point for LNR has been determined. Divergences may result from differences in sample sizes, inclusion criteria, pathological types, evaluation standard, and statistical methods. To avoid these limitations and to confirm the prognostic value of LNR and the modified TNM staging system, longitudinal studies on large sample size with multicenter analysis should be carried out preferably with the increased mean number of collected LNs.
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