Epidemiology, treatment, and outcomes in locally advanced spindle cell lung cancer.

e21048 Background: Spindle cell lung cancer (SpCC) is a rare type of NSCLC which portends a poor prognosis. Due to the rarity of diagnosis, there is a dearth of information about the epidemiology and overall survival for these patients. Methods: We performed a retrospective analysis using the SEER database from 1975-2016 to study the demographics, treatment modalities and outcomes for patients with locally advanced SpCC. Data regarding age, sex, race, pathological grade, staging, treatment, overall and disease specific survival was extracted. Hazards ratios were calculated to identify any difference in mortality between patients who received surgery alone versus those who received adjuvant chemotherapy or radiation. Results: A total of 936 cases of SpCC were identified, out of which 367 (39%) patients had locally advanced disease. 84% cases were diagnosed after the age of 60, with peak incidence occurring in the 70-74 age group. 87% were Caucasians, and 56% were males. 68% of the tumors were poorly differentiated. In terms of the treatment modalities for locally advanced SpCC, surgical resection was performed only in 58.5% cases. 27% patients received systemic chemotherapy, out of which 50% was in the adjuvant setting after surgery. 32 % patients received radiation therapy, only 38.5% of which was in the adjuvant setting. No statistically significant difference in mortality was seen in patients who received surgery alone vs adjuvant RT vs adjuvant chemotherapy. However, pts who did not receive surgery had a higher odds of mortality (OR = 4.2, p value 0.0001). Similarly, pts who only received chemotherapy alone had a higher odds of mortality vs those who received chemotherapy along with surgery (OR = 3.4, p-0.045), Overall survival was 25% for patients with localized disease, 9.5% for regional and only 2.6% for distant metastatic disease. For locally advanced SpCC, the observed cumulative 1-year survival was 54.8 % and declined to 29.2% after 5 years. Conclusions: Majority of the spindle cell carcinoma cases are poorly differentiated and present at an advanced stage at the time of diagnosis. For locally advanced SpCC, surgical resection can improve survival. Randomized trials are needed to test efficacy of adjuvant therapies.