The novel WHO 2010 classification for gastrointestinal neuroendocrine tumours correlates well with the metastatic potential of rectal neuroendocrine tumours.
BACKGROUND
Approximately 10-15% of gastroenteropancreatic neuroendocrine tumours (NETs, carcinoids) occur in the rectum, some of which are potentially able to metastasize. The new WHO 2010 classification of NETs applies to all gastroenteropancreatic NETs, but no reports have studied its correlation with the prognosis of rectal NETs.


METHODS
We retrospectively classified 73 rectal NETs according to the novel WHO 2010 and the previous WHO 2000 classifications. The aim was to assess the validity of the classifications in distinguishing indolent rectal NETs from metastasising tumours.


RESULTS
Using the WHO 2010 criteria, we identified 61 G1 tumours, none of which had metastasised during follow-up. Of 11 G2 tumours, 9 had shown distant metastases. The only G3 neuroendocrine carcinoma that occurred had been disseminated at initial presentation.


CONCLUSIONS
Our results show that rectal NETs classified as G1 according to the WHO 2010 classification have an indolent clinical course, whereas G2 NETs often metastasise. The WHO 2010 classification of NETs predicts the metastatic potential of rectal NETs better than the WHO 2000 classification.
Department of Pathology, Haartman Institute and HUSLAB, Helsinki University Central Hospital, Haarmaninkatu 3, Helsinki, Finland. juha.jernman@pshp.fi
Juha
J
Jernman
Matti J
MJ
Välimäki
Johanna
J
Louhimo
Caj
C
Haglund
Johanna
J
Arola
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002965:Classification / Q000379:methods*; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D005770:Gastrointestinal Neoplasms / Q000145:classification* / Q000175:diagnosis / Q000401:mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging / Q000379:methods; D018358:Neuroendocrine Tumors / Q000145:classification* / Q000175:diagnosis / Q000401:mortality / Q000473:pathology*; D011237:Predictive Value of Tests; D012004:Rectal Neoplasms / Q000145:classification* / Q000175:diagnosis / Q000401:mortality / Q000473:pathology*; D012042:Registries; D014944:World Health Organization; D055815:Young Adult