Lung Metastases in Newly Diagnosed Hypo-pharyngeal Cancer: A Population-Based Study

Objectives: To characterize the incidence proportions and survival probability of patients with hypo-pharyngeal cancer and lung metastases. Design: Secondary data analysis Setting: The Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute. Participants: We identified 2814 adult patients diagnosed with hypo-pharyngeal cancer between 2010 and 2014 for whom the status of lung metastases was known. Patients with an unknown follow-up were excluded; leaving 2714 patients in this cohort. Main outcome measures: Multivariable logistic and Cox regression models were performed to identify the risk factors associated with the presence of lung metastases at diagnosis and five-year all-cause mortality respectively. Results: We identified 128 patients with lung metastases at the time of diagnosis of hypo-pharyngeal cancer, representing 4.7% of the entire cohort. Females were less likely to have lung metastases (15, 11.7%)(P=0.037). Incidences of lung metastases was higher among patients with histological grade III/IV (56, 43.8%)(P<0.001). Patients with lung metastases had a larger tumor size(49.9690.25mm, P <0.001). For each 10 mm increase in tumor size, the odds of having lung metastases increased by 6.6%. Patients with lung metastases had a shorter survival time(HR:3.05, 95% CI:2.17-4.28, P<0.001). For age, tumor size increase and black study subjects were also significantly associated with a shorter survival time. Conclusion: Our study provides insight into the epidemiology of lung metastases in patients with hypo-pharyngeal cancer. When the tumor is diagnosed, we should pay close attention to the sex, race, tumor size and histological grade in order to quickly detect the distant metastases.