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Difficulties for the analysis of rare cancers. Missing cases Example: angiosarcoma of liver Including false cases Example: malignant digestive endocrine tumours. Difficulties for the technician to record rare cancers.
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Difficulties for the analysis of rare cancers • Missing cases Example: angiosarcoma of liver • Including false cases Example: malignant digestive endocrine tumours
Difficulties for the technician to record rare cancers - Unusual morphology in pathologic records seems commonly easy to identify for technicians - Pathologists themselves are not experts in these cancers the conclusion of their reports may often be not clear It may be difficult to identify the morphologic code corresponding to these cases
Example: angiosarcoma of liver: very rare and not well known Various codes in the literature , ~ 200 annual new cases per year …? IARC SCIENTIFIC PUBLICATIONS, 1997 Chapter 4. Histological groups D.M. Parkin, J. Ferlay, K. Shanmugaratnam, L. Sobin, L. Teppo and S.L. Whelan
Example : How to choose the good code for angiosarcoma of liver ? Survival from rare cancer in adults: a population-based studyThe Lancet Oncology, 2006
Example : How to choose the good code for angiosarcoma of liver ? Survival from rare cancer in adults: a population-based studyThe Lancet Oncology, 2006
Proposalfor rare cancers • Identification in the database of rare cancers by a inedited specific code (XXXX) • Precise codification of the morphologic code in a second variable after validation by a pathologist and/or a clinician This aims in an: - improvement in the identification and the extraction of rare cancers - improvement in the quality of data
Malignant digestive endocrine tumours (mdet) • Not so rare (~ 0.8/100 000) • Butdifficulties with the rules of codification : • Heterogeneity of this group of cancer arising from diverse sites • How to distinguish between benign and malignant tumours • Changes in the classification over time
Mdet : difficulties with the rules of codification Behaviour : / 2 / 3
Example : colon cancers. High frequency of appendix mdet, usually benign Eurocare, 1985-1994
Example : colon cancers. High frequency of appendix mdet, usually benign 30% 39% 40% 80% Eurocare, 1985-1994
Example : mdet Eurocare. Information on the differentiation, a major pronostic factor
Example : mdet Eurocare. Information on the differentiation, a major prognostic factor
Proposal Before the final analysis: • To ensure that homogenous rules are used between registries • To compare incidence and relative survival rates by subsite, by morphology, by period… in order to mark possible disparities in the registration between countries and between registries in the same registry
conclusion There is a need to ask each registry their rules of codification before analysing rare cancers cases