Abstract 2042: The effect of time to treatment on survival varies by disease stage and surgery status for patients with colorectal cancer
Authors: Yang Liu , Bui Aileen , Myint Anthony , May Folasade P. 
Published: September 2020

Background: Despite national treatment guidelines for colorectal cancer (CRC), time to treatment (TT) is increasing. Currently, the impact of TT on survival among individuals with CRC is unknown. We examined the relationship between TT and CRC-specific survival and determined predictors of TT in the United States.

Methods: We used the Surveillance, Epidemiology, and End Result (SEER) Registry-18 database to identify patients age≥20 with a histologic diagnosis of colon cancer (CC) or rectal cancer (RC) and no other malignancies between 2010 and 2015. TT was defined as the number of months between CRC diagnosis and first treatment regardless of the type of treatment. We conducted Cox proportional hazard regression models to examine the association between TT and CRC-specific survival, adjusting for year of diagnosis, age, sex, race, socioeconomic index, insurance, stage, grade, and surgery, and accounting for the moderation effect of tumor stage and surgery on survival in association with TT. We used logistic regression to explore the relationship between longer TT (&gt;1 month) and stage, surgery, and year of diagnosis.

Results: A total of 138,060 patients were included. During a median follow-up time of 30 (IQR 36) months, 4-year CRC-specific survival was 69.6% in CC and 72.7% in RC. Mean TT (SD) was 0.5 (1.0) in CC and 0.9 (1.2) months in RC. Among CC patients, 93% underwent surgery, compared to 82% of RC patients. After adjusting for other factors, the impact of TT varied by stage and surgery (interaction test P values&lt;0.05). For stage I patients who did not undergo surgery, a 1-month increase in TT was associated with about 10% higher risk of death (CC: HR=1.12 [95% CI, 1.01-1.23]; RC: HR=1.10 [95%CI,1.02-1.18]). Inverse associations were found in later stage CC and RC. A 1-month increase in TT was significantly associated with 9%-22% lower risk of death in stage II/III/IV CC and this effect was more pronounced in patients who underwent surgery (Stage II: HR[surgery]=0.78, HR[no surgery]=0.87; Stage III: HR[surgery]=0.81, HR[no surgery]=0.90; Stage IV: HR[surgery]=0.82, HR[no surgery]=0.91). A similar effect was found in stage IV RC with an HR of 0.80 (95%CI: 0.76, 0.84) for patients undergoing surgery and 0.85 (95%CI: 0.82, 0.88) for those without surgery. Accounting for all covariates, patients diagnosed in later years, with earlier stage disease (ORs: 1.19-1.74, stage I/II/III vs. stage IV), and with surgery (CC: OR=3.71 [95%CI, 3.3-4.1]; RC: OR=2.3 [95%CI, 2.1-2.5]) were more likely to have longer TT (&gt;1 month).

Conclusion: Longer TT was associated with decreased survival for stage I CC/RC patients who did not have surgery. However, longer TT was associated with increased survival for late stage CC/RC and the impact was more pronounced for those who underwent surgery. Our findings highlight the complexity of late stage and surgical cases, and the importance of sufficient workup before treatment.

Citation Format: Liu Yang, Aileen Bui, Anthony Myint, Folasade P. May. The effect of time to treatment on survival varies by disease stage and surgery status for patients with colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2042.