Cancer screening is one of medicine's great success stories. According to the World Health Organization, regular cervical cancer screening can reduce cervical cancer mortality by up to 80%. [1] Similar success has been seen with breast and colorectal cancer screening programs, demonstrating the power of finding cancer before symptoms appear. [2,3]

However, routine screening today focuses on just a handful of cancers. Together, the remaining cancers account for approximately 78% of cancer deaths worldwide. [4]

So why don't we routinely screen for more cancers?

Although these cancers are very different, the reasons they lack routine screening programs fall into three broad categories.

Three Reasons Many Cancers Still Lack Routine Screening

1. We Don't Yet Have Accurate Enough Tests

Screening millions of healthy people requires extremely accurate tests. Even a small number of false-positive results can lead to unnecessary scans, procedures, anxiety, and healthcare costs.

This remains a major challenge for cancers such as pancreatic, ovarian, and bladder cancer. Researchers have investigated blood biomarkers including CA 19-9 for pancreatic cancer and CA-125 for ovarian cancer, as well as imaging approaches such as MRI, endoscopic ultrasound, and transvaginal ultrasound. Urine-based biomarkers have also been explored for bladder cancer. While these methods can be useful in certain clinical settings, none have demonstrated the accuracy needed for routine population-wide screening. [5-7]

The biology of these cancers makes screening even more difficult. Pancreatic and ovarian cancers often develop deep within the body and may produce few symptoms in their earliest stages. As a result, many cases are diagnosed only after the disease has progressed. [8] Even with modern imaging technologies, routinely screening millions of healthy individuals would be difficult, costly, and unlikely to provide sufficient benefit.

2. Some Screening Programs Are Limited to High-Risk Groups

Sometimes the challenge is not detecting cancer, but identifying who should be screened.

Screening is most effective when the people being tested have a meaningful chance of developing the disease. If a cancer is relatively uncommon in the general population, screening millions of healthy people may lead to many false-positive results, unnecessary investigations, and increased healthcare costs while detecting relatively few cancers.

For this reason, some screening programs are recommended only for people at substantially higher risk. For example, low-dose CT screening is recommended for certain people with a significant smoking history and has been shown to reduce lung cancer mortality in high-risk populations. [9] Likewise, liver cancer surveillance is often reserved for people with cirrhosis or chronic hepatitis B, whose risk of liver cancer is substantially higher than that of the general population. [10]

By focusing on people most likely to benefit, these targeted screening programs achieve a better balance between benefits, potential harms, and healthcare resources.

3. Finding More Cancer Is Not Always Better

An effective screening program must improve outcomes, not simply detect more cancers.

Prostate cancer provides a well-known example. PSA testing can identify many prostate cancers, but some of these tumors may never become life-threatening. PSA testing can also produce false-positive results, meaning some men undergo additional testing or biopsies despite not having prostate cancer. [11]

A similar lesson emerged from South Korea, where widespread thyroid ultrasound screening led to a more than fifteen-fold increase in thyroid cancer diagnoses without a corresponding reduction in mortality. Many of the additional cancers detected were unlikely to have caused harm, leading some patients to undergo unnecessary treatment and its associated risks. [12]

The Future of Cancer Screening

Many cancers are still diagnosed only after symptoms appear, when treatment options may be more limited.

Because stage IV cancers account for a disproportionate share of cancer-related deaths, researchers have estimated that shifting cancers from metastatic disease to earlier-stage diagnosis could reduce cancer-related deaths by approximately 15%. [13]

This has fueled interest in multi-cancer early detection (MCED) tests, which analyze a single blood sample for biological signals associated with multiple cancers.

Unlike many traditional single-cancer biomarkers, MCED tests are generally designed with high specificity to help minimize false-positive results and unnecessary follow-up testing. Rather than looking for a single cancer, they simultaneously assess signals associated with multiple cancer types from a single blood draw. [14]

MCED tests are not intended to replace established screening programs for breast, cervical, or colorectal cancer. Instead, they are being developed to complement routine screening and help identify cancers for which screening programs do not currently exist.

References

1. World Health Organization. Cervical cancer screening. Global Health Observatory Indicator Metadata Registry. Accessed June 26, 2026. https://www.who.int/data/gho/indicator-metadata-registry/imr-details/3240

2. Nelson HD, Fu R, Cantor A, et al. Effectiveness of breast cancer screening: systematic review and meta-analysis to update the 2009 U.S. Preventive Services Task Force recommendation. Ann Intern Med. 2016;164(4):244-255.

3. US Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. JAMA. 2021;325(19):1965-1977.

4. Bray F, Laversanne M, Sung H, et al. Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin. 2024;74(3):229-263.

5. US Preventive Services Task Force. Screening for pancreatic cancer: US Preventive Services Task Force reaffirmation recommendation statement. JAMA. 2019;322(5):438-444.

6. US Preventive Services Task Force. Ovarian cancer: screening. JAMA. 2018;319(6):588-594.

7. Chou R, Dana T. Screening adults for bladder cancer: a review of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med. 2010;153(7):461-468.

8. National Cancer Institute. Pancreatic Cancer Treatment (PDQ®) – Patient Version. Accessed June 26, 2026.

9. US Preventive Services Task Force. Screening for lung cancer: US Preventive Services Task Force recommendation statement. JAMA. 2021;325(10):962-970.

10. National Comprehensive Cancer Network. Hepatobiliary Cancers. Version 2.2026. National Comprehensive Cancer Network; 2026.

11. Academy of Medical Royal Colleges. PSA testing for men aged 80 years and above. Evidence-Based Interventions Programme. Accessed June 26, 2026.

12. Ahn HS, Kim HJ, Welch HG. Korea's thyroid-cancer "epidemic": screening and overdiagnosis. N Engl J Med. 2014;371(19):1765-1767.

13. Clarke CA, Hubbell E, Kurian AW, et al. Projected reductions in absolute cancer-related deaths from diagnosing cancers before metastasis. BMJ Open. 2020;10.

14. Klein EA, Richards D, Cohn A, et al. Clinical validation of a targeted methylation-based multi-cancer early detection test using an independent validation set. Ann Oncol. 2021;32(9):1167-1177.