The SEER program selects high-quality cancer registries that represent diverse geographic areas across the United States.

The American Joint Committee on Cancer classification of malignant tumors (i.e., tumor, node, metastasis staging) was not available for the patients diagnosed between 19.

A stage variable for those patients was created using the information on the size of the primary tumor, extent of spread to nearby lymph nodes, and tumor metastasis to other organs of the body (Please refer to the Supplementary Appendix 1).

The patient identification algorithm is presented in Supplementary Appendix 2.

The major portions of cancer treatment costs are incurred in the initial phase when the disease is diagnosed and in the terminal phase when the physicians extend their efforts to improve the patient’s quality of life.

The average annual cost in men and women was US$8,025 and US$5,124, respectively.

The overall survival after the diagnosis of cancer was 8.42 years.

We examined three treatment phases—initial, continuation, and terminal care—as well as the entire longitudinal profile of each patient from the date of diagnosis to death.

The initial phase of care included the primary course of therapy and any adjuvant therapy within the first 6 months of diagnosis.

Diagnoses are coded using International Classification of Diseases-9To be included in the study, patients must have been 66 years or older and enrolled in Medicare at the time of diagnosis, must have had continuous Parts A and B coverage during the entire observation period, and must have had histologically confirmed anal cancer.

Patients were excluded if they were enrolled in Medicare managed care, if they were diagnosed only at death, or if the month of their diagnosis was unknown.

In health services research, cost information is required for economic evaluation studies, burden of disease studies, and budget impact analyses.