Treatment regimens and survival among patients with head and neck squamous cell carcinoma from Mizo tribal population in northeast India - a single centre, retrospective cohort study.

Background: Patients with early-stage head and neck squamous cell carcinoma (HNSCC) are treated using a single-modality approach that involves either surgery (S) or radiotherapy (RT). Conversely, those with advanced-stage disease are treated using a multi-modality approach incorporating a combination of chemotherapy (CT), RT and S. In addition to behavioural factors, such as alcohol and tobacco use, clinical parameters, such as leukocyte and neutrophil counts and T and N classification, have been linked to the survival of patients with head and neck cancer. This retrospective study was designed to provide insights into the types of treatment (induction chemotherapy [IC], concurrent chemoradiotherapy [CCRT], S and RT) administered to patients with HNSCC in Mizoram, analyse their 2-year outcome, and identify potential factors that may affect the response to treatment. Methods: A retrospective cohort study was conducted using patients diagnosed with HNSCC between 2017 and 2020 in Mizoram, northeast India. Data on clinical and demographic factors and treatments provided were collected from medical records from the Mizoram State Cancer Institute, Mizoram. Overall survival (OS) and progression free survival (PFS) were determined for each factor using the Kaplan-Meier method and compared using the log-rank test. Cox regression analysis was used to identify the factors that affected OS and PFS. Multicollinearity test was performed between the predictors using a variance inflation factor cut-off point of 2. Findings: A retrospective study was performed on 210 patients with HNSCC who were followed up for a period of 2 years. The findings revealed that hypopharynx was the most affected site, followed by the nasopharynx, oral cavity, oropharynx, and larynx. Regarding treatment regimens, 85/210 (40.5%) of the patients received IC along with CCRT or RT in a sequential manner. Moreover, 86/210 (41.0%) underwent CCRT alone, 22/210 (10.5%) received RT alone and 17/210 (8.1%) underwent surgery followed by adjuvant CCRT or RT. Two-year OS and PFS estimated using the Kaplan-Meier analysis were 78.1% (95% CI = 72.4%-84.2%) and 57.4% (95% CI = 50.8%-64.8%), respectively. Log-rank test showed that leucocytosis (p = 0.015) and neutrophilia (p = 0.014) exerted effects on OS, whereas nodal involvement (p = 0.005), neutrophilia (p = 0.043) and IC (p = 0.010) exerted effects on PFS. Multivariate analysis indicated that leucocytosis (p = 0.010 [OS], 0.025 [PFS]), neutrophilia (p = 0.029, 0.033), cancer site (laryngeal) (p = 0.009, 0.028) and nodal involvement (N2) (p = 0.020, 0.001) were predictors of poor OS and PFS. Interpretation: OS was better than PFS in HNSCC patients from Mizo population. Multi-modality approach offered survival advantages over single-modality approach. Leucocytosis, neutrophilia, nodal involvement, and cancer sites were associated with poor OS and PFS. More comprehensive research with a larger sample size is needed to confirm the findings from this study. Funding: There is no funding for this study.