1. Difficulties for the analysis of rare cancers Missing cases Example: angiosarcoma of liver Including false cases Example: malignant digestive endocrine tumours

2. 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

3. IARC SCIENTIFIC PUBLICATIONS, 1997 Chapter 4. Histological groups D.M. Parkin, J. Ferlay, K. Shanmugaratnam, L. Sobin, L. Teppo and S.L. Whelan Example: angiosarcoma of liver: very rare and not well known Various codes in the literature, ~ 200 annual new cases per year …?

4. Example : How to choose the good code for angiosarcoma of liver ? Survival from rare cancer in adults: a population-based study The Lancet Oncology, 2006

5. Example : How to choose the good code for angiosarcoma of liver ? Survival from rare cancer in adults: a population-based study The Lancet Oncology, 2006

6. Proposal for 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

7. Malignant digestive endocrine tumours (mdet) Not so rare (~ 0.8/100 000) But difficulties 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

8. Well differentiated benign ET Well differentiated borderline ET Well differentiated endocrine carcinoma undifferentiated endocrine carcinoma DifferenciationWell differentiated Undifferentiated AngioinvasionNoPossible SizeStomach, Small intestine: < 1cm Appendix, colon, rectum : < 2 cm Pancreas : < 2 cm Stomach, Small intestine : >1 cm Appendix, colon, rectum : > 2 cm Pancreas : > 2cm Stomach, Small intestine : >1 cm Appendix, colon, rectum : > 2 cm Pancreas : >3 cmo Mitotic Index< 2< 2Pancreas > 22 to 10> 10 Proliferation Index (Ki67) < 2 %often > 2 %2 to 15 %> 15 % local invasionDigestive tumour : mucosae/submucosae Pancreas : intra- pancreatic Digestive tumour : mucosae/muscularis propria Pancreas : intra- pancreatic Digestive tumour (out appendix): > Muscularis propria Appendix : invasion of the visceral peritoneum Pancreas : extra- pancreatic extension Metastasesno Possible / 3Behaviour : / 2 Mdet : difficulties with the rules of codification

9. Example : colon cancers. High frequency of appendix mdet, usually benign Eurocare, 1985-1994

10. Example : colon cancers. High frequency of appendix mdet, usually benign 30 % 40 % 80% 39 % Eurocare, 1985-1994

11. Example : mdet Eurocare. Information on the differentiation, a major pronostic factor

12. Example : mdet Eurocare. Information on the differentiation, a major prognostic factor

13. 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

14. conclusion There is a need to ask each registry their rules of codification before analysing rare cancers cases