LAUSR

With great interest, I read a recent retrospective study quantifying the prognostic impact of neutrophil-to-lymphocyte ratio (NLR) on head and neck cancer (HNSCC) with lung metastasis [1]. In this study, Yanni A and colleagues concluded that pretreatment NLR is an independent prognostic factor of mortality and lung metastasis development. However, several pitfalls may better be concerned. First, the authors wrongly utilize lung metastasis-free survival (LMFS) to compare patients with NLR > 2.62 to NLR < 2.62 in both groups (the authors’ Fig. 2D). In principle, LMFS is defined as the time from grouping to confirmed evidence of lung metastasis on imaging or death from any cause, whichever occurred first [2]. Furthermore, the authors also stated that “Lung-metastasis-free-survival (LMFS) was calculated in patients who developed HNSCC-lung metastasis and defined as the interval between diagnosis and lung metastasis”. Thus, the authors cannot enroll HNSCC patients with lung metastasis after grouping. In other words, the authors should assess LMFS in no-lung-metastasis-group (NLM-group), not in the lung-metastasis-group (LM-group) or both groups. NLR using FMFS may better be reassessed to explore the relationship between pretreatment NLR and lung metastasis development. Second, the title of the authors’ study might be not exact. As the authors stated in their conclusion, “Our data revealed that pretreatment NLR is an independent prognostic factor of mortality and lung metastasis development. However, the prognostic value of NLR is not confirmed in patients who suffered from lung metastasis”. Thus, the title may better be revised to “Neutrophil-to-lymphocyte ratio as a prognostic marker for head and neck cancer with lung metastasis development: a retrospective study”. Third, based on the small number of patients, several imbalances existed in patient characteristics in the authors’ Table 1, including alcohol use (p = 0.005), localization (p = 0.013), T status (p = 0.049), N status (p = 0.039), and NLR at diagnosis (p = 0.001). It is well acknowledged that these imbalances would potentially influence the authors to accurately assess patients’ prognostic endpoints in both groups [3, 4]. Moreover, the authors forgot to include localization to conduct the cox regression analysis in the authors’ Tables 3–5. I thank Yanni A and colleagues for their efforts on NLR for HNSCC with lung metastasis. But due to the small number of samples, several concerns might impact the reliability of the authors’ conclusion. I am looking forward to their positive responses.