Background: Severe lymphopenia during treatment is considered to be a poor prognostic factor. The current literature lacks information regarding its impact on various outcomes in locally advanced head-and-neck cancer patients in a prospective setting.

Methods: We recently published a randomised study comparing cisplatin–radiation with nimotuzumab cisplatin–radiation. The database of this study was used for the present analysis. The impact of severe lymphopenia (grade 4 lymphopenia) on progression-free survival (PFS), locoregional control (LRC) and overall survival (OS) was studied using the Kaplan–Meier method and Cox regression analysis. The binary logistic regression analysis was used to see the effect of various factors on the development of severe lymphopenia.

Results: We had a total of 536 patients, of which 521 patients (97.7%) developed lymphopenia. Grade 1 lymphopenia was noted in 10 (1.9%) patients, grade 2 in 100 (18.8%), grade 3 in 338 (63.1%) and grade 4 in 73 (13.7%) patients. The median PFS was 20.53 and 60.33 months in severe and non-severe lymphopenia, respectively (hazard ratio, 0.797; p-value = 0.208). The median duration of LRC was 56.3 months in severe lymphopenia, whereas it was not reached in non-severe lymphopenia (hazard ratio, 0.81; p-value = 0.337). The median OS was 28.46 versus 47.13 months in severe and non-severe lymphopenia, respectively (hazard ratio, 0.76; p-value = 0.11). Of various risk factors, gender was significantly associated with severe lymphopenia.

Conclusion: The occurrence of severe lymphopenia was not significantly associated with the outcomes. Gender is the only risk factor significantly linked to severe lymphopenia.