Responses

Extract

Crocetti and Buiatti raise an interesting issue with respect to the classification of multiple primary tumors. The Upper Midwest Oncology Registry Services (TUMORS) classifies multiple primaries according to the Surveillance, Epidemiology, and End Results (SEER) ¹ recommendations as described in the Standards of the Commission on Cancer ( 1 ). SEER classification has been the standard in the United States since 1973 and precedes the International Agency for Research on Cancer (IARC) guidelines. Within the United States, SEER data are widely used to assure comparability. Primary cancers classified according to SEER rules can be converted using IARC rules, because the SEER classification is more detailed than the IARC. WC have reclassified the multiple primaries of our original seven patients according to IARC rules as published in 1991 ( 2 ). We were unable to obtain a copy of the internal report mentioned by Crocetti and Buiatti that may contain modified rules. By IARC rules, four of the seven patients had five or more primary cancers, and one patient had four primary cancers. The two additional patients had one and two primary cancers, respectively. The difference between the SEER and IARC categorization is due to IARC counting multiple colon cancers in the same person as a single primary cancer. Here is a list of the original patients, the total number of primary cancers using IARC rules, and a list of primary sites.