Preface

Abstract

Established in 1973, the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute (NCI) has been a valued source of high-quality information for cancer incidence and survival in the United States. SEER data are used in a variety of research studies to explore cancer incidence and survival for etiologic and outcomes research related to cancer. These studies include exploring factors that influence trends, analyzing and understanding the cancer burden at a national and local level, and describing health disparities among subpopulations. Data are collected on approximately 450 000 cases of malignant and in situ cancers each year, including information on patient demographics, primary tumor site, tumor morphology and stage at diagnosis, first course of treatment, and mortality outcomes. The registry community strives to capture clinically relevant information by periodically expanding the scope of data collected, such as incorporating the latest staging definitions, as well as predictive and prognostic factors as they become part of standard care. Staging describes the extent of an individual's cancer at the time of diagnosis and plays a vital role in managing patient care. Cancer staging reflects prognosis and is used in determining appropriate treatment for cancer patients. It is an essential component in many areas of cancer research, from defining eligibility criteria in clinical trials to evaluating the impact of cancer interventions and treatment advances in epidemiologic and health services research. The American Joint Committee on Cancer (AJCC) leads the effort in the United States to develop a standardized staging system and collaborates with the Union for International Cancer Control (UICC) to maintain a system that is used worldwide. Cancer staging guidelines as well as classification systems for tumors continue to evolve over time and are updated periodically to reflect advances in cancer care and diagnosis. The AJCC and UICC work closely with cancer registrars to ensure that registries can capture the most current staging definitions. The SEER Program and its predecessors such as the End Results Program have collected information to stage cancers and have adapted their data collection to evolving staging requirements (Fig. 1). Staging over time. Traditionally, staging represented anatomic information regarding the scope of the disease, and this information was summarized into 3 categories: the extent to which the tumor has invaded nearby tissue (T; including size of the tumor for some sites), whether the cancer has spread to nearby lymph nodes (N), and whether the cancer has metastasized to other parts of the body (M). Together, T, N, and M form the basis for cancer staging. With advances in medical technologies and the introduction of precision medicine and targeted therapies, staging systems incorporated factors that influence prognosis and treatment decisions to reflect current medical practice. As the complexity of the components that determine prognosis continued to increase, it became increasingly challenging to maintain staging systems that would both provide consistency over time and capture the factors influencing treatment decisions in the current medical setting. To address the challenge, a set of building blocks was developed that would provide the foundation needed to translate the extent of disease information into multiple staging systems and enhance the anatomic staging information with additional clinically relevant factors such as biomarkers and prognostic factors. This new approach resulted in the creation of the Collaborative Stage Data Collection System (CS). The first version of Collaborative Stage (CSv1) was introduced for cases diagnosed in 2004 and coincided with the release of the 6th edition of the AJCC Cancer Staging Manual.1 CS is a unified data collection system designed to use a single set of data elements based on extent of disease and clinically relevant factors that both meets the needs of multiple staging systems and eliminates duplicate data collection by cancer registrars reporting to facility-based and central population-based registries. The project was sponsored by the AJCC in collaboration with NCI's SEER Program, the American College of Surgeons Commission on Cancer (CoC), the Centers for Disease Control and Prevention's National Program of Cancer Registries, the National Cancer Registrars Association, the North American Association of Central Cancer Registries, and the Canadian Cancer Society's National Cancer Institute of Canada. The Collaborative Staging system was updated in 2010 (CSv2) in conjunction with the release of the 7th edition of the AJCC Cancer Staging Manual (AJCC 7th)2. The authors of the AJCC 7th present the T, N, M, and stage descriptions along with a section on prognostic factors for which collection is recommended. These recommendations are the basis for the development and collection of the site-speci