2. Materials
cancer, tumor, death, Cancer
REGRESSION, CANCER, TUMOR, CANCER
The study population was extracted from the SEER database of the United States National Cancer Institute using its software SEER*Stat 8.4.0.1 (seer.cancer.gov/seerstat/), which is a collection of 17 population-based cancer registries covering around 26.5% of the USA population. Informed consent for patient information to be published in this article was not obtained because data for this research are available from SEER database (Available data included age at diagnosis, gender, race, marital status, income, residence information, sequence number, primary site, histology type, tumor stage, laterality, Ann Arbor stage, B symptoms, nodal status, systemic treatment, surgery therapy, radiotherapy, chemotherapy, survival months, vital status, and cause of death. The main outcomes of interest were OS and CSS. We define OS as the time from diagnosis to death attributed to any cause, whereas CSS is defined as the length of time from the diagnosis to the death that was attributable to H&NNHL.We employed SPSS software (version 24.0, Chicago, IL) and R-software (version 4.2.1, Multivariable analysis using the Cox proportional hazards regression model was performed to identify significant independent prognostic factors in the training cohort, for which 