The order of colorectal cancer diagnosis seems to have a significant impact on outcomes in patients with multiple primary malignancies, according to the results of a study of Surveillance, Epidemiology, and End Results (SEER) Program data. Findings from the study were published in the Journal of the American College of Surgeons. Patients who were diagnosed with colorectal cancer first of their multiple malignancies did better overall than those who developed colorectal cancer later—even compared with patients who had colorectal cancer alone.
“We expected [patients with] isolated colorectal cancer to fare best, but patients with CRC diagnosed first, followed by another cancer had the best survival rates. This was surprising; we hypothesized [that] patients with only a colorectal cancer diagnosis would do best,” stated first study author Anjelli Wignakumar, MBBS, BSc (Hons), clinical research fellow in the Department of Colorectal Surgery, Ellen Leifer Shulman & Steven Shulman Digestive Disease Center at Cleveland Clinic Florida.
Study Methods and Results
Study authors conducted a retrospective analysis of all patients with colorectal adenocarcinoma in the SEER database from 2000 to 2020 (N = 592,063). Patients were divided into three groups based on their diagnoses, including patients with colorectal cancer as their only malignancy:
• Group A; n = 424,920; 71.8, and patients with colorectal cancer as the first of multiple primary malignancies;
• Group B; n = 70,432; 11.9%, and patients with colorectal cancer as the second of their multiple primary malignancies;
• Group C; n = 96,711; 16.3%.
Patients in group A tended to be younger (P < .001), had elevated pretreated carcinoembryonic antigen levels (P < .001), more frequent liver metastases (P < .001), more frequent lung metastases (P < .001), and systemic adjuvant treatments (P < .001) than patients in group B or C. Additionally, in group A, there were more patients with T4 tumors (P < .001) and fewer surgical treatments (P < .001) than in either group B or C.
“Group A patients were younger, presented more aggressively (higher liver metastases), and were less likely to receive surgery—possibly because their disease was further along,” said Dr. Wignakumar.
Group B had more male patients (P < .001) and left-sided colorectal tumors than the other groups. Group C had more patients with right-sided colorectal tumors than the other groups, which are associated with an aggressive biology.
The highest overall survival was seen in group B—50.4 months vs 41.8 months in group A and 39.2 months in group C. Cancer-specific survival was also highest in group B—51.3 months vs 42.2 months in group A and 39.8 months in group C.
“Group C (colorectal cancer as the second cancer) had the worst outcomes. Clinicians must treat these as high-risk cases and consider aggressive therapy,” said coauthor Sameh H. Emile MBBCh, MSc, MD, FACS, Project Scientist in the Department of Colorectal Surgery, Ellen Leifer Shulman & Steven Shulman Digestive Disease Center, Cleveland Clinic Florida.
Patients in group B were also more likely to undergo surgery (20.5%) than patients in group A (13.0%) or C (14.3%).
The study authors suggested that the better outcomes seen in group B were likely because of the increased surveillance and medical care for these patients following their cancer diagnosis, allowing for other primary malignancies to be caught earlier. Additionally, they hypothesized that prior cancer treatments may prime the immune system to fight other cancers. The researchers stressed that regular screening remains essential for all groups.
Disclosure: For full disclosures of the study authors, visit journals.lww.com.
