Lymph node ratio may improve OSCC survival prediction
MedWire News: The ratio of metastatic lymph nodes to number of nodes examined - the lymph node ratio (LNR) - is an independent prognostic factor for oral squamous cell carcinoma (OSCC), and could improve risk stratification, say Australian investigators.
The presence of lymph node metastases is a critical prognostic factor in OSCC. However, the LNR is an important prognostic factor in colorectal, gastric, esophageal, breast, and bladder cancer, and there is evidence to suggest that it may be a more sophisticated method of stratifying recurrence risk and survival.
Ardalan Ebrahimi, from Prince Alfred Hospital in Sydney, studied the records of 313 OSCC patients who underwent neck dissection with curative intent between 1987 and 2009. The LNR was determined and its association with overall survival, disease-specific survival, local recurrence, regional recurrence, and distant recurrence was determined.
In 204 patients with clinically negative neck, 37.7% had pathologically proven cervical nodal metastases. Nodal metastases were confirmed pathologically in 80.7% of 109 patients with clinically positive necks. The average nodal yield per neck dissection was 27.4. In all, 165 (52.7%) patients had pathologically proven nodal metastases, with an average of 3.4 positive nodes and a median nodal ratio of 6.9%.
Median overall survival was 10.1 years, with 48 of 78 deaths due to OSCC. In patients with positive nodes, median survival was 9.7 years, with 38 of 56 deaths due to OSCC, the team notes in the journal Head and Neck.
On multivariate analysis taking into account potential covariates, age ≥65 years versus <65 years, T classification (T3-T4 vs T1-T2), involved margin, and LNR were all significant predictors of overall survival, at hazard ratios of 2.8, 2.3, 2.2, and 1.6, respectively. Age, T classification, and LNR were predictors of disease-specific survival, at hazard ratios of 2.4, 2.5, and 1.6, respectively.
Compared with an LNR of <2.5%, an LNR of 2.5-7.5%, 7.5-20.0%, and >20.0% was associated with a 2.6-, 3.7-, and 4.4-fold increased risk for death from OSCC, respectively.
As the LNR is necessarily affected by the nodal yield during dissection, the team says: "Although this study was not designed to determine what the minimum or optimal nodal yield should be in patients with OSCC undergoing neck dissection, our results support the notion that we need to work toward such a recommendation."
By Liam Davenport