K. Nguyen-Ta2, M. Turner2, K. Chen3, S. Kalavacherla3, A. Kothari4, C. Clarke4, W. Mehtsun1, U. Maduekwe4 3University Of California – San Diego, School Of Medicine, San Diego, CA, USA 4Medical College Of Wisconsin, Surgical Oncology, Milwaukee, WI, USA 1University Of California – San Diego, Surgical Oncology, San Diego, CA, USA 2University Of California – San Diego, Surgery, San Diego, CA, USA
Introduction:
Metastatic gastric cancer has a dismal prognosis with a median survival of less than 12 months. Recent randomized controlled trials demonstrated improved survival outcomes for stage IV gastric cancer patients who received immunotherapy in addition to chemotherapy. Consequently, the combination of immunotherapy and chemotherapy is now first-line treatment for metastatic gastric cancer patients. The purpose of our study is to examine early adoption of immunotherapy as treatment in metastatic gastric cancer at a population level and determine if a similar survival benefit is observed.
Methods:
Using the National Cancer Database, we restricted our analysis to stage IV gastric cancer patients from 2004-2018. The proportion of patients who received immunotherapy was assessed over the study period. Overall survival was compared between patients who received immunotherapy and those who did not using Kaplan-Meier estimates and multivariable Cox proportional hazards regression.
Results:
Between 2004 and 2018, 59,112 patients were diagnosed with stage IV gastric cancer. Of these patients, 2,887 (4.9%) received immunotherapy. Findings showed a significant increase in immunotherapy utilization from 0.6% in 2012 to 13.5% in 2018 (P <0.001). In multivariable analysis adjusted for age, gender, race, rurality, comorbidity, insurance status, facility type, histology, grade, tumor location, treatment with chemotherapy, treatment with immunotherapy; receipt of immunotherapy (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.72-0.79; P < .001), being of Asian/Pacific Islander descent (HR, 0.82; 95% CI, 0.79-0.87; P<.001), receipt of oncologic care at academic facilities (HR, 0.84; 95% CI, 0.82-0.85; P < .001) and treatment in a more recent time period (2018 vs. 2004 HR, 0.92; 95% CI, 0.87-0.97; P = .002) were associated with a decreased hazard of death.
Conclusion:
In this retrospective cohort study, the use of immunotherapy among metastatic gastric cancer patients significantly increased over the study period. Receipt of immunotherapy, being of Asian/Pacific Islander descent, and care at academic facilities were associated with an increased overall survival. As the uptake of immunotherapy increases for metastatic gastric patients nationally, an understanding of how this novel therapy is allocated nationally is prudent.
