Octogenarian patients with colorectal cancer: Characterizing an emerging clinical entity.

Aim: To characterize colorectal cancer (CRC) in octogenarians as compared with younger patients.

Methods: A single-center, retrospective cohort study which included patients diagnosed with CRC at the age of 80 years or older between 2008-2013. A control group included consecutive patients younger than 80 years diagnosed with CRC during the same period. Clinicopathological characteristics, treatment and outcome were compared between the groups. Fisher's exact test was used for dichotomous variables and was used for variables with more than two categories. Overall survival was assessed by Kaplan-Meier survival analysis, with the log-rank test. Cancer specific survival (CSS) and disease-free survival were assessed by the Cox proportional hazards model, with the Fine and Gray correction for non-cancer death as a competing risk.

Results: The study included 350 patients, 175 patients in each group. Median follow-up was 40.2 mo (range 1.8-97.5). Several significant differences were noted. Octogenarians had a higher proportion of Ashkenazi ethnicity (64.8% 47.9%, < 0.001), a higher rate of personal history of other malignancies (22.4% 13.7%, = 0.035) and lower rates of family history of any cancer (36.6% 64.6%, < 0.001) and family history of CRC (14.4% 27.3%, = 0.006). CRC diagnosis by screening was less frequent in octogenarians (5.7% 20%, < 0.001) and presentation with performance status (PS) of 0-1 was less common in octogenarians (71% 93.9%, < 0.001). Octogenarians were more likely to have tumors located in the right colon (45.7% 34.3%, = 0.029) and had a lower prevalence of well differentiated histology (10.4% 19.3%, = 0.025). They received less treatment and treatment was less aggressive, both in patients with metastatic and non-metastatic disease, regardless of PS. Their 5-year CSS was worse (63.4% 77.6%, = 0.009), both for metastatic (21% 43%, = 0.03) and for non-metastatic disease (76% 88%, = 0.028).

Conclusion: Octogenarians presented with several distinct characteristics and had worse outcome. Further research is warranted to better define this growing population.