Why Cancer Screening Remains Important for Long-Term Cancer Survivors

About 1 in 9 older adults who had lived at least five years after breast, prostate, colon or rectal cancer were later diagnosed with a new, unrelated cancer, according to a large study published online Oct. 13, 2026, in JNCI: Journal of the National Cancer Institute. More than 40% of these later cancers were types that routine screening is designed to find, which the researchers say supports keeping up with screening beyond the five-year mark.

A second primary cancer is a new cancer that starts in a different place or cell type from the first one. It is not the original cancer coming back (a recurrence) or spreading (a metastasis).

What the Study Looked At

Researchers used SEER-Medicare, a database that links national cancer registry records to Medicare claims. They studied 90,261 people who were diagnosed with breast, prostate, colon or rectal cancer at age 66 or older between 2003 and 2011 and who survived at least five years.

The team looked for a "late" second cancer, meaning an invasive cancer diagnosed at least five years after the first diagnosis, over up to eight years of follow-up. They grouped the new cancers into blood cancers, cancers that can be found by screening (breast, prostate, lung, colon and rectal) and cancers without routine screening.

What It Found

• Overall, 11.2% of survivors (10,116 people) developed at least one late second cancer.
• Across the groups, about 10% to 14% of survivors developed a late second cancer 5 to 13 years after their first diagnosis. Prostate cancer survivors had the highest rate over eight years.
• Cancers without routine screening made up the largest share of the new cancers. Still, over 40% were types that screening can detect.
• The most common second cancer depended on the first one. Lung cancer was most common among colon cancer survivors (14.9% of their second cancers) and rectal cancer survivors (16.1%). Bladder cancer was most common among prostate cancer survivors (17.0%). A new breast cancer was most common among breast cancer survivors (36.5%).

The study shows how often these cancers happened. It does not show that the first cancer or its treatment caused the second one. Shared risk factors such as age, smoking and family history also play a role.

What's Still Unknown

Everyone in the study was 66 or older when first diagnosed, and SEER-Medicare includes only people in traditional Medicare, so the results may not apply to younger survivors or people in Medicare Advantage. The people in the study were diagnosed between 2003 and 2011, before some newer treatments were used. The study also does not say which screening schedule works best for long-term survivors.

What It Means for You

Reaching five years after cancer is a milestone worth celebrating, but it is not the end of follow-up care. Recommended screenings, such as mammograms, colonoscopies and, for people with a heavy smoking history, lung cancer screening, still matter for long-term survivors. CURE has previously explained what happens when a patient develops a second cancer years after treatment.

Not every screening test is right for every older adult. The value of screening depends on your overall health and life expectancy, so it is a decision to make with your care team.

Questions to Ask Your Care Team

• Now that I am past five years, which cancer screenings should I keep getting, and how often?
• Am I eligible for lung cancer screening based on my smoking history?
• Do I have a written survivorship care plan, and who is in charge of my follow-up?
• Which new symptoms should prompt me to call you?

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