Profile and Outcomes of Patients with Subsequent Colorectal Cancer after a Prior Malignancy in the US

Abstract

Introduction: The relationship between a subsequent colorectal cancer and a prior malignancy is complex, with possible etiological, genetic, and therapeutic implications. Little is known about the epidemiological and clinical profile of this category of patients. The present study aims to determine the factors associated with improved survival among these patients. Methods: We used the Surveillance, Epidemiology, and End Results 18 Registry 1975-2016 to systematically analyze patients who developed secondary colorectal cancer after a prior cancer diagnosis. The outcome was the latency interval between the initial primary malignancy diagnosis and a subsequent colorectal cancer diagnosis. In addition, using the Cox regression model, we determined the factors associated with improved survival. Results: A total of 58,748 patients subsequently developed colorectal cancer after a prior malignancy. Most of the patients were White (82.8%), 45.9% women with a mean age at diagnosis of primary malignancy of 67.9± 12.0 years. The commonest prior malignancies were prostate cancer (19.3%), breast cancer (13.4%), urinary bladder cancer (4.9%), and endometrial cancer (4.6%). The latency interval from developing a subsequent colorectal malignancy was 6.2 ± 5.3 yrs. (prostate cancer), 8.2 ± 7.1 yrs. (breast cancer), 7.0 ± 6.7 y. (Urinary bladder cancer), and 10.0 ± 8.1 yrs. (endometrial cancer). Age >45 years, Black or Hispanic ethnicity, male sex, and short-latency interval were associated with the worst survival. Conclusion: There is a significant disparity in outcomes among patients with secondary colorectal cancer even though they had undergone some form of treatment and active surveillance after a prior cancer diagnosis.