The hypopharyngeal cancer cases with lymph node metastasis were staged as III/IV according to the AJCC TNM staging system. Approximately 70 to 85% of the patients reported in larger series were diagnosed as having stage III or IV disease at presentation. 
The management of stages III/IV hypopharyngeal cancer has been relatively unsatisfactory owing to local recurrence and distant metastasis. Optimal therapy has remained a matter of debate, especially with regard to treatment intensity and sequencing. 
Although treatment strategies of cancer advance tremendously, no significant survival improvements were observed in pN+ hypopharyngeal cancer patients diagnosed at different periods as shown in current results, which was also observed for laryngeal cancer and supposed to be caused by inappropriate patients selecting and lack of better index for guiding postoperative therapy. 
It is plausible that selecting high risk patients is important in the choice of optimal treatment strategies. Current study clearly identified that the LNR is an important prognostic factor for CSS in hypopharyngeal cancer patients with lymph node metastasis. As compared with the N classification, the R classification using the cutoff points 0.05/0.30 showed better predictive ability for CSS and OS, with a lower AIC value and a higher C-index value. The survival curves for R1, R2 and R3 patients were clearly separate even after a 15-year follow-up period, whereas intersection of the survival curves for N 1–3 patients was found after a 10-year follow-up period. The similar survival estimates for R1 and R0 patients further confirmed the role of LNR in stratifying patients (a lower LNR to select lower risk patients).
Over the past three decades, more attention has been paid to the identification of factors that might help the surgeon to assess the precise risk of failure in individual patients. 
The best predictive index should be easily assessed and dependent on the target measured. For example in primary radiotherapy, volume of the primary tumor may be a predictive factor. 
For surgical approaches to organ preservation, anatomic sub-localization and extension of the primary tumor are more relevant factors. In the case of postoperative radiotherapy for hypopharyngeal cancer, adverse features were defined as extracapsular nodal spread, positive margins, pT3 or pT4 primary tumor, N2 or N3 nodal disease, selected pT1-T2, N0-N1, perineural invasion and vascular embolism according to the NCCN guidelines. 
When the CSS and OS of individual R classification patients, with or without postoperative radiotherapy, were compared in the current study, survival benefits were observed for R2 and R3 patients. Combining the N and R classifications together can also select more high risk patients for postoperative radiotherapy than using the N classification alone (62.6% vs. 71.4%). All these results support the fact that R2 and R3 should be defined as adverse features for the postoperative management of hypopharyngeal cancer. Because information regarding the details of radiotherapy (the radiation techniques, dose delivered and fractions, and use of concurrent chemotherapy, etc) and pathological reports (margin status, extracapsular extension, perineural invasion and vascular embolism, etc) are not available in the SEER database, the definitive role of the R classification in postoperative staging and selecting high risk patients for postoperative concurrent chemoradiotherapy could not be discussed in the current study, and is deserving of further research.
Although we have adjusted for all available patient and tumor characteristics in our analysis, as with all SEER based studies, our study was limited by the information available in the database. The SEER database is dependent on the individual physician reporting on the classification of the patient, tumor and treatment characteristics. In this way, it is representative of national patterns of cancer care and has a large population base; however, it is also subject to inconsistencies. Although the number of lymph nodes examined and the number of positive nodes is information that can easily be reported with accuracy, there are still cases that were rejected for inclusion in the current study because of disconcordant information with regard to the N classification and the number of lymph node metastases. The quality of neck dissection achieved by the surgeon, and the quantity of lymph nodes harvested and examined by the pathologist will substantially change the LNR and the results. On the other hand, patients who have a lower number of lymph nodes resected (a relatively lower quality of operation), which may cause inflation of the LNR and a higher R classification, will be assessed as a high risk group. The LNR is an index not only of disease burden but also of surgical standards. This is the reason why the current study, together with studies on cancer from other sites, showed that the LNR improved the predictive ability of survival relative to the N classification. 
In conclusion, our analysis of the SEER database revealed a significant association between the LNR and survival of hypopharyngeal cancer patients. Using the cutoff points 0.05/0.30, the hypopharyngeal cancer patients with lymph node metastasis were classified into R1, R2 and R3 risk groups. The R classification can be used together with the N classification to select high-risk patients for postoperative treatment. However, more and prospective studies were still needed to confirm the prognostic role of LNR for hypophayryngeal cancer and more clinical evidence should be obtained.