A major new study using one of the world’s largest cancer databases has found that the timing of a colorectal cancer (CRC) diagnosis—especially in relation to other cancers—can significantly affect a patient’s survival outcomes.
The research, published in the Journal of the American College of Surgeons, draws from data in the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program and includes cases from 2000 to 2020.
Researchers grouped over 480,000 patients into three categories based on their cancer history:
- Group A: Patients diagnosed with only colorectal cancer (71.8%)
- Group B: Patients diagnosed with CRC first, followed later by another type of cancer (11.9%)
- Group C: Patients diagnosed with another cancer first, followed by CRC (16.3%)
Surprisingly, it was Group B, those diagnosed first with colorectal cancer and later with another type of cancer, who had the best survival outcomes. On average, they lived 50.4 months overall and 51.3 months in terms of cancer-specific survival. These patients were also the most likely to receive surgery for their CRC (20.5%), which is known to improve outcomes.
In contrast, Group C, who developed colorectal cancer after surviving another type of cancer, had the poorest outcomes. These patients more often had aggressive right-sided tumors and were less likely to undergo surgery. Group A, those with only CRC, had worse outcomes than Group B and were more likely to present with advanced disease, including liver metastases.
“We expected patients with only CRC to do best, but those who had CRC first, then another cancer, had the highest survival. This was unexpected,” said lead author Dr. Anjelli Wignakumar, a clinical research fellow at the Cleveland Clinic Florida.
Why would multiple cancer patients fare better?
The researchers suggest several possible explanations. Patients who have already been diagnosed with cancer may be more closely monitored and undergo more frequent screening, which helps detect new cancers earlier when they are easier to treat.
They may also be more engaged with their healthcare, have adopted healthier lifestyles, or have benefited from immune system changes brought on by their first cancer treatment.
On the other hand, the younger age and more aggressive presentation seen in Group A might explain why outcomes were worse in that group, despite having only one cancer diagnosis.
These findings highlight the need for more nuanced screening strategies. Patients with a history of non-colorectal cancers may require more frequent or aggressive CRC screening, as they appear to be at higher risk of worse outcomes when CRC develops later.
“Patients in Group C—those with CRC as a second cancer—had the worst prognosis. We must treat these cases as high-risk and consider more aggressive interventions,” said Dr. Sameh Emile, a co-author and colorectal surgery researcher.
Dr. Steven Wexner, senior author and director of the Digestive Disease Center at Cleveland Clinic Florida, offered a clear message for patients: “Be vigilant. Just because you’ve survived one cancer doesn’t mean you’re in the clear. Early detection of a second cancer could save your life. Follow all recommended screenings.”
In summary, this large study reveals a counterintuitive but critical insight: being diagnosed with colorectal cancer first—before any other cancers—may actually improve survival outcomes, likely due to earlier detection, more surgery, and continued engagement with the healthcare system.
Patients and providers alike are urged to remain proactive about cancer screenings, especially after an initial diagnosis.
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The research findings can be found in Journal of the American College of Surgeons.
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