Methods
tumor, death, T stage, cancer, tumors, early-onset stage I, AJCC, Cancer
TUMOR, METASTASIS, CANCER, TUMORS, CANCER
The data were obtained from the SEER Program, which is dedicated to collecting and providing cancer statistics with the aim of reducing the cancer burden in the USA. We used data collected from 2012 to 2015. These data included baseline patient and tumor characteristics and survival information. The inclusion criteria for this study were (a) age under 50 years; (b) surgery performed; (c) postoperative pathological diagnosis of stage I–II CC without distance metastasis; and (d) ≥ 12 regional nodes examined. The exclusion criteria were (a) no prior tumor; (b) unknown histological grade; (c) unknown marital status; (d) unknown race; (e) death from other tumors and unknown cause of death; and (f) survival time recorded as zero. Ultimately, our study cohort comprised 3528 patients with early-onset stage I–II CC.These following variables were extracted and included in the analysis: baseline patient characteristics (race, sex, age at diagnosis, survival [months], marital, and vital status), tumor features (tumor site, pathological grade, tumor size, TNM stage, and T stage), and treatment strategy (chemotherapy). Staging was in accordance with the seventh edition of the American Joint Committee on Cancer (AJCC) TNM classification. Race was classified as white, black, or other. Sex was stratified as male or female. Two age groups were created: ≤ 35 and > 35 years. Pathological grades I–IV were categorized as well differentiated, moderately differentiated, poorly differentiated, and undifferentiated. Additional study variables comprised tumor site (left or right side), chemotherapy (no or yes), marital status (married or unmarried), tumor size (≤ 5 cm or > 5 cm) and T stage (T1, T2, T3, T4). Overall survival (OS) time was defined as the time from diagnosis to death from any cause.All eligible patients were randomly allocated to a training (