A cancer registry is an information system that collects, stores, and manages data on every person diagnosed with cancer in a defined area. These registries exist so public health officials, researchers, and hospitals can track how many people get cancer, what types they get, how they’re treated, and how long they survive. Together, the two major national programs cover 100% of the U.S. population, making cancer one of the most thoroughly tracked diseases in the country.
How Cancer Registries Work
Cancer data collection begins when someone is diagnosed or receives treatment at a hospital, outpatient clinic, surgical center, laboratory, or doctor’s office. By law, these facilities are required to report new cancer cases to their state’s central cancer registry. The cases can be submitted electronically or on paper, following nationally recognized reporting protocols so that data stays consistent from one facility to the next.
Registries don’t just sit back and wait for reports to come in. Staff members actively visit hospitals and clinics to make sure no cases slip through the cracks. This process, called casefinding, is what makes registry data so reliable. Reporting timelines vary by state, but they tend to be strict. New Hampshire, for example, requires basic case identification within 45 days of diagnosis and full case details within 180 days.
What Information Gets Recorded
Each cancer case includes three broad categories of data:
- Patient demographics: name, age, sex, race, ethnicity, and birthplace.
- Tumor characteristics: the cell type, the organ where the cancer started, how far it has spread, and increasingly, genomic information like specific biomarkers that may predict outcomes or response to therapy.
- Treatment details: whether the patient had surgery, radiation, chemotherapy, hormone therapy, immunotherapy, or some combination.
All of this is recorded using a standardized data dictionary maintained by the North American Association of Central Cancer Registries (NAACCR). That dictionary is developed collaboratively by the CDC, the National Cancer Institute, the American College of Surgeons, and Canadian cancer registries, so hospitals and state registries across the continent are coding data the same way.
Hospital Registries vs. Population-Based Registries
There are two main types, and they serve different purposes. A hospital-based registry tracks cancer patients treated at a single facility. Its goals are practical and internal: improving patient care, supporting clinical research, providing data for professional education, and helping hospital administrators plan resources.
A population-based registry covers everyone diagnosed with cancer across an entire geographic area, typically a state. These registries focus on the bigger picture: calculating cancer rates and trends over time, identifying which populations are hit hardest, evaluating screening programs, and measuring whether public health interventions are actually working. When you see a statistic like “the five-year survival rate for breast cancer is 90%,” that number comes from population-based registry data.
The Two National Programs
Two federal programs work together to ensure every cancer case in the U.S. is captured. The Surveillance, Epidemiology, and End Results (SEER) Program has been run by the National Cancer Institute since 1973, originally created as a result of the National Cancer Act of 1971. The National Program of Cancer Registries (NPCR), administered by the CDC, was established by Congress in 1992 to fill coverage gaps.
Between them, SEER and NPCR have achieved 100% population coverage across all 50 states and the District of Columbia for cases diagnosed from 2003 onward. Even for 2001 and 2002, coverage reached 99%. This means researchers can study cancer patterns for the entire country, not just a sample.
Why Registries Matter for Public Health
Because registry data captures essentially every cancer case, it serves as the foundation for three core functions. First, it allows officials to define and monitor cancer incidence at local, state, and national levels, so they can spot rising rates in a particular region or demographic group. Second, it reveals patterns of treatment, showing whether patients in rural areas receive different care than those in cities, or whether certain populations face barriers to standard therapies. Third, it provides the data needed to evaluate whether prevention efforts, like anti-smoking campaigns or HPV vaccination programs, are actually reducing cancer cases and improving survival.
Registry data also powers the kind of research that shapes treatment guidelines. When scientists need to know whether survival rates for a specific cancer have improved over the past two decades, or whether a new screening method is catching cancers earlier, they turn to registry databases. These aren’t small studies. They draw on millions of records spanning decades.
Who Collects the Data
The professionals who gather and manage this information are called cancer registrars, formally credentialed as Oncology Data Specialists. Becoming one requires at minimum an associate’s degree (including coursework in human anatomy and physiology) and either completion of an accredited cancer registry education program or roughly one year of full-time experience in the field. Their day-to-day work includes casefinding, abstracting medical records into standardized codes, following up on patient outcomes, submitting data to state and national databases, and ensuring reporting standards are met.
How Reporting Is Being Modernized
Traditionally, much of cancer reporting involved registrars manually reviewing medical records and entering data. That’s changing. The CDC’s NPCR program has developed software called eMaRC Plus that can receive and process cancer data electronically from pathology laboratories using standardized health data formats. More recently, federal agencies have been working with laboratories and the broader health IT community to implement FHIR (Fast Healthcare Interoperability Resources), a modern data-sharing standard that allows electronic health records to transmit cancer pathology information directly to state registries with less manual intervention.
These tools don’t eliminate the need for human registrars, but they speed up the process and reduce the chance of missed cases. As electronic health records become more standardized, the goal is for cancer reporting to happen as close to automatically as possible, getting critical data into the hands of researchers and public health planners faster than the traditional paper-and-visit workflow allows.