Impact of the Ki-67 proliferation index on response to peptide receptor radionuclide therapy.
OBJECTIVE
The role of the Ki-67 tumour proliferation index (PI) in predicting the efficacy of peptide receptor radionuclide therapy (PRRT) in gastroenteropancreatic tumours (GEP-NET) remains undetermined. This single-centre analysis focused on the potential therapeutic impact of this immunohistochemical parameter.


METHODS
A total of 81 consecutive GEP-NET patients treated with (177)Lu-DOTA-octreotate (mean activity of 7.9 GBq per cycle, usually four treatment cycles at standard intervals of 3 months) were retrospectively analysed. Both an evaluable PI and tumour response (modified SWOG criteria) were required for patient inclusion.


RESULTS
Response of tumours with a PI of ≤20% (partial response 40%, minor response 15%, stable disease 34%, progressive disease 11%) was comparable in all PI subsets, including those with a PI of 20%. However, G3 tumours (PI > 20%) showed progression in 71% of patients.


CONCLUSIONS
Response to PRRT is consistent over the PI range of ≤20% (G1 + G2). Contrary to preliminary previous suggestions, a PI of 15% or 20% should not preclude candidates from somatostatin receptor-targeted radiotherapy.
Ezziddin
Samer
S
Department of Nuclear Medicine, University Hospital, Bonn, Germany. samer.ezziddin@ukb.uni-bonn.de
Opitz
Martin
M
Attassi
Mared
M
Biermann
Kim
K
Sabet
Amir
A
Guhlke
Stefan
S
Brockmann
Holger
H
Willinek
Winfried
W
Wardelmann
Eva
E
Biersack
Hans-Jürgen
HJ
Ahmadzadehfar
Hojjat
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D049109:Cell Proliferation; D015331:Cohort Studies; D004067:Digestive System Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D018000:Receptors, Peptide / Q000627:therapeutic use*; D012189:Retrospective Studies; D016896:Treatment Outcome
D019394:Ki-67 Antigen; D018000:Receptors, Peptide