EDITORIAL

Checking up on the Surveillance, Epidemiology, and End Results Program

Donald E. Henson, Jorge Albores-Saavedra

Affiliations of authors: Office of Cancer Prevention and Control, The George Washington University Cancer Institute, The George Washington University Medical Center, Washington, DC (DEH); Louisiana State University Health Sciences Center, Shreveport (JAS)

Correspondence to: Donald E. Henson, MD, Office of Cancer Prevention and Control, The George Washington University Cancer Institute, The George Washington University Medical Center, Washington, DC (e-mail: patdeh{at}gwumc.edu)

The SEER1 Program (Surveillance, Epidemiology, and End Results) of the National Cancer Institute has played a leading role in guiding public policy, stimulating research, and reflecting progress in cancer control in the United States. Begun in 1973, SEER collects and publishes cancer incidence and mortality data on more than 10% of the U.S. population. Currently, the SEER database contains more than 3 million cases of in situ and invasive cancer. In addition to demographic data, SEER collects variables such as histologic tumor type, estrogen receptor status in cases of breast cancer, and extent of disease, which are important clinical parameters.

Population based, SEER reflects cancer as seen in urban areas, the suburbs, university settings, and isolated community hospitals. There is no patient selection. In short, SEER provides data about the neoplastic pathology of the general population of the United States, and it reflects the work of surgeons, oncologists, and pathologists.

Whereas the information submitted to SEER on age, gender, date of diagnosis, and stage of disease is reasonably precise, doubts are often expressed about variables that result from subjective and complex judgments, such as the histologic interpretation of tumors, reporting norms, and terminology (1,2). In this issue of the Journal, Field et al. (3) present valuable insights into the accuracy of SEER data with regard to the histologic typing of lung cancer.

The morphology of cancer has been with us for 100 years. It is not only the common language of oncology but also a starting point for therapy. Histological tumor type is often a prognostic factor; it often directs the type of treatment and may signal changes in etiology. Analyses of site-oriented incident trends may be misleading unless the histologic tumor types are also taken into account. Gastric cancer, for example, has been declining for years in the United States, but on close inspection, the decrease affects only the intestinal type. The less common diffuse type has increased (4).

SEER takes information directly from the pathology report as submitted. SEER does not arrange for second opinions, does not refer to consultants, nor summon experts to verify the diagnoses. Thus, what the pathologist reports is recorded in SEER. However, a fortuitous research study has led to a check of the histologic types of lung cancer reported to SEER.

Iowa has a statewide SEER registry; all cases of cancer diagnosed in the state are registered. From 1992 to 1999, Iowa conducted a Radon Lung Cancer Study in women to determine a potential relationship between smoking status, radon exposure, and lung cancer. (5) As part of the study, the pathology specimens from women with lung cancer were centrally collected and subjected to independent expert review by two pathologists who were blinded to the original diagnosis. This review, therefore, was conducted on the cases previously submitted to the Iowa tumor registry by statewide hospitals. Although it was not the intent of the radon study, this independent review eventually provided an opportunity for a review of SEER lung cancer submissions. As mentioned by the authors (3), there have been very few studies that have compared registry data with an independent review of the same data.

The results showed no statistical difference in the distribution of histologic types in the Radon Lung Cancer Study compared with those in the SEER cancer registry. Thus, the authors concluded that the histologic diagnosis of lung cancer as recorded in SEER in Iowa is reasonably reliable, but nonetheless to be safe expressed the caveat that independent review may be desirable for precise histologic typing. For a large population-based database, this conclusion is noteworthy.

The reviewing pathologists followed a slightly different procedure than that used by the hospital pathologists, adding credibility to the conclusion. They discussed disagreements and even obtained special stains or additional information to reach diagnostic agreement. This may not always be done in hospital settings or in everyday pathology practice. In pathology, the assumption is made, perhaps justifiably, that precision reflects accuracy; that is, when several pathologists agree on a diagnosis, it is likely to be the correct one.

The authors also pointed out the obvious—that cytologic or biopsy specimens cannot always be used to report a final diagnosis because the specimen is very small or tissue architecture is not present. A more reliable diagnosis is likely to be made on the resected specimen.

This comparison was an unintended benefit of the radon study. Comparisons of data that come by accident are often more powerful than "gold standards." However, it is difficult to decidewhether the SEER served as a gold standard for the radon study or the study as a gold standard for SEER. A true gold standard would contain no disagreements.

SEER serves as a national database for anatomic pathology. Therefore, it places a heavy responsibility on individual pathologists and on professional pathology organizations to ensure that the diagnostic information provided by the profession to SEER is accurate and based on meaningful systems of classification. It further places the responsibility to ensure accurate encoding of diagnostic data, uniform recording of complex diagnosis, and the continued evaluation of coding schemes. In return, SEER serves as a mechanism of quality. Patterns derived from matching the histologic diagnoses with factors such as age, anatomic site, gender, and incident ratios for individual pathology departments can be compared with established patterns that can be calculated from existing information stored in SEER. In effect, these established patterns are analogous to the analytical confidence limits used in clinical chemistry laboratories.

Although pathologists may occasionally agonize over the diagnosis of an individual case (1,2,69), in the population, it is the histologic patterns of cancer that matter. As SEER matures, it becomes a valuable tool with far-reaching implications for the study of cancer. While some variation in individual diagnosis will occur, the regression of large numbers is taking effect, and the patterns of histologic tumor types are converging to their mean. While we can quibble whether SEER was a gold standard for the radon study, it certainly is a gold mine.

NOTES

1 Editor's note: SEER is a set of geographically defined, population-based, central cancer registries in the United States, operated by local nonprofit organizations under contract to the National Cancer Institute (NCI). Registry data are submitted electronically without personal identifiers to the NCI on a biannual basis, and the NCI makes the data available to the public for scientific research. Back

REFERENCES

1 Compton CC. Surgical pathology for the oncology patient in the age of standardization: of margins, micrometastasis, and molecular markers. Semin Radiat Oncol 2003;13:382–8.[ISI][Medline]

2 Renshaw AA, Young ML, Jiroutek MR. How many cases need to be reviewed to compare performance in surgical pathology? Am J Clin Pathol 2003;119:388–91.[ISI][Medline]

3 Field RW, Smith BJ, Platz CE, Neuberger JS, Brus CP, Lynch CF. Lung cancer histologic type in the Surveillance, Epidemiology, and End Results Registry versus independent review. J Natl Cancer Inst 2004;96:1105–7.[Abstract/Free Full Text]

4 Henson DE, Dittus C, Younes M, Nguyen H, Albores-Saavedra J. Differential trends in the intestinal and diffuse types of gastric carcinoma in the US, 1973-2000: increase in the signet ring cell type. Arch Pathol Lab Med. 2004;128:765–70.[Medline]

5 Field RW, Steck DJ, Smith BJ, Brus CP, Fisher EL, Neuberger JS, et al. Residential radon gas exposure and lung cancer: the Iowa Radon Lung Cancer Study. Am J Epidemiol 2000;151:1091–102.[Abstract]

6 Tsung JS. Institutional pathology consultation. Am J Surg Pathol 2004;28:399–402.[ISI][Medline]

7 Macartney JC, Henson DE, Codling BW. Quality assurance in anatomic pathology. Am J Clin Pathol 1981;75:467–75.[ISI][Medline]

8 Abt AB, Abt LG, Olt GJ. The effect of interinstitution anatomic pathology consultation on patient care. Arch Pathol Lab Med 1995;119:514–7.[ISI][Medline]

9 Cowan DF. Quality assurance in anatomic pathology. An information system approach. Arch Pathol Lab Med. 1990;114:129–34.[ISI][Medline]


This article has been cited by other articles in HighWire Press-hosted journals:


             
Copyright © 2004 Oxford University Press (unless otherwise stated)
Oxford University Press Privacy Policy and Legal Statement